Dictionary of Electrical Terms, Abbreviations, and Acronyms

A B C D E F G H I J K L M N O P Q R S T U V WXYZ

Note: Words in bold within the text of a definition indicate other definitions in this dictionary.

Disclaimer: This dictionary was compiled by CRSP MC staff as an information resource only.  We assume no liability for incorrect or outdated information presented here, and make no guarantees that any of the information is correct.


1-CP: 1-month coincident peak for year.

12-CP: 12-month coincident peak average.

6X16: Abbreviation used to refer to the on-peak period for electricity sales. That is, 16 hours per day for 6 days per week.

6X8+24: Abbreviation used to refer to the off-peak period for electricity sales. That is, 8 hours per day for 6 days per week, plus all day Sunday.

7X24: Abbreviation used to refer to a continuous period for electricity sales. That is, 24 hours per day for 7 days per week.

$/kW/month: Monthly charge for capacity (i.e., dollars per kilowatt (kW) per month).


Access Charge: A fixed tariff rate that recovers the portion of a utility's transmission revenue requirement not recovered through the variable Usage Charge.

ACE: Area Control Error - The instantaneous difference between generation and load in a utility Control Area. The Control Area Operator's SCADA system monitors ACE and minimizes it using Regulation. This parameter is used to determine a control area's control performance with respects to its' impact on system frequency.

ACH: Automated Clearinghouse

Acid Rain: Also called acid precipitation or acid deposition, acid rain is precipitation containing harmful amounts of nitric and sulfuric acids formed primarily by nitrogen oxides and sulfur oxides released into the atmosphere when fossil fuels are burned. It can be wet precipitation (rain, snow, or fog) or dry precipitation (absorbed gaseous and particulate matter, aerosol particles or dust). Acid rain has a pH below 5.6. Normal rain has a pH of about 5.6, which is slightly acidic. The term pH is a measure of acidity or alkalinity and ranges from 0 to 14. A pH measurement of 7 is regarded as neutral. Measurements below 7 indicate increased acidity, while those above indicate increased alkalinity.

Acre Foot: Unit of hydraulic volume measurement used to describe a quantity of storage in a reservoir, or the amount of water used for agricultural purposes. The volume covering one acre to a depth of one foot.

  • 1 acre foot = 325,829 gallons
  • 1 acre foot = 43,560 ft³
  • 1 acre foot = 1233.47 meters³

ACSR: Aluminum Conductor, Steel Reinforced. A type of conductor used in overhead transmission lines, that contains an arrangement of aluminum and steel strands. The aluminum strands provide the current carrying capacity while the steel strands provide reinforcing strength and resistance to sag when heated due to heavy electrical loading and/or weather conditions.

Actual Imbalance: A deviation between last accepted generation and load schedule compared to the actual generation and load delivered.

Actual Peak Load Reductions: The actual reduction in annual peak load (measured in kilowatts) achieved by consumers that participate in a utility DSM program. It reflects the real changes in the demand for electricity resulting from a utility DSM program that is in effect at the same time the utility experiences its annual peak load, as opposed to the installed peak load reduction capability (i.e., Potential Peak Load Reduction). It should account for the regular cycling of energy efficient units during the period of annual peak load.

Adverse Hydro (Adverse Water Conditions): Water Conditions limiting the production of hydroelectric power either from low or restricted water supply or reduced gross head.

AGC: Automatic Generation Control - Automatic Generation Control is equipment that automatically adjusts a Control Area's generation from a central location to maintain its interchange schedule plus frequency bias.

Aggregator: An entity responsible for planning, scheduling, accounting, billing and settlement for energy deliveries from the aggregator's portfolio of Sellers (generators, purchases) and/or Buyers (loads or sales).

AHP: Available Hydro Power - The actual amount of hydroelectric power available during a given time period from SLCA/IP powerplants, depending on hydrological conditions. AHP may be less than, equal to, or greater than SHP.

Airway Marker Ball: A round, colored ball, usually aviation orange, attached to the conductors or overhead ground wire for daytime marking. Available in various sizes from 20” diameter and larger.

Allowance for Funds Used During Construction (AFUDC): A noncash item representing the estimated composite interest costs of debt and a return on equity funds used to finance construction. The allowance is capitalized in the property accounts and included in income.

A-LP: Animas LaPlata Project, a Bureau of Reclamation water project located near Durango in southwestern Colorado. A-LP is a participating project of the CRSP.

Alternating Current: Term applied to an electric current or voltage that reverses its direction of flow at regular intervals and has alternately positive and negative values, the average value of which over a period of time is zero. Compare Direct Current.

Ambient Temperature: The temperature of the surrounding cooling medium, such as gas or liquid, which comes into contact with the heated parts of the apparatus.

Ammeter: A meter placed in a circuit that measures the number of amperes of electric current flowing in a circuit.

Ampere (A): The unit of measurement of electric current. It is proportional to the quantity of electron flow through a conductor past a given point in one second. It is the unit current produced in a circuit by one Volt applied across a resistance of one Ohm.

AMWG: Adaptive Management Work Group

Ancillary Services: Ancillary services are those services necessary to support the transmission of energy from resources to loads while maintaining reliable operation of the Transmission Provider's transmission system in accordance with good utility practice.
Four real-power ancillary services -

Regulation: Generator is on-line, utilizing automatic generation control, and the unit can respond quickly to control center requests for up and down movements.
Spinning reserve: Generator is on-line and synchronized to the grid. It can increase output immediately in response to a major outage and can reach full capacity within 16 minutes.
Supplemental reserve: Same as spinning reserve, but the unit doesn't have to respond immediately. Thus, unit can be off-line, but capable of reaching full capacity within 15 minutes.
Replacement reserve: Same as supplemental reserve, but response time is stretched to as long as 60 minutes.
Source: Eric Hirst

The six required Ancillary Services as defined in FERC Orders No. 888 and 889 are:

  • scheduling, system control and dispatch service - schedules the amount of energy to be delivered, assigning load and ensuring operational security, among other tasks;
  • reactive supply and voltage control from generation sources service - maintains correct voltage through adjustment to generator output;
  • energy imbalance service - provides energy correction for any hourly mismatch between a transmission customer's energy supply and demand served;
  • regulation and frequency response service - follows the moment-to-moment variations in the demand or supply in the control area;
  • operating spinning reserve service - provides immediate back-up service from a reserve unit to serve load in case of a system contingency;
  • operating supplemental reserve service - serves load when a contingency exists; not available immediately to serve load but can be available within a short time.

Annual Effects: The total effects in energy use (measured in megawatthours) and peak load (measured in kilowatts) caused by all participants in the DSM programs that are in effect during a given year. It includes new and existing participants in existing programs (those implemented in prior years that are in place during the given year) and all participants in new programs (those implemented during the given year). The effects of new participants in existing programs and all participants in new programs should be based on their start-up dates (i.e., if participants enter a program in July, only the effects from July to December should be reported). If start-up dates are unknown and cannot be reasonably estimated, the effects can be annualized (i.e., assume the participants were initiated into the program on January 1 of the given year). The Annual Effects should consider the useful life of efficiency measures, by accounting for building demolition, equipment degradation and attrition.

Annual Transmission Costs: The total annual cost of the Transmission System shall be the amount specified in Schedule 1 until amended by the Transmission Provider or modified by the Commission.

Annunciator: A visual signaling device indicating one or more conditions that exist or have existed in a associated circuit.

Anthracite: A hard, black lustrous coal, often referred to as hard coal, containing a high percentage of fixed carbon and low percentage of volatile matter.

Arcing: The process of current leaping the gap from one electrode to another.

Armor Rod: Protective pre-formed wires wrapped around aluminum conductor to prevent damage at point of support. Also used to repair minor conductor damage.

Arrester: A power system device which limits the voltage of a surge applied to its terminals and interrupts any follow current. Commonly called a surge arrester, a surge diverter, or a lightning arrester.

Ash: Impurities consisting of silica, iron, alumina, and other noncombustible matter that are contained in coal. Ash increases the weight of coal, adds to the cost of handling, and can affect its burning characteristics. Ash content is measured as a percent by weight of coal on an "as received" or a "dry" (moisture-free, usually part of a laboratory analysis) basis.

Asset: An economic resource, tangible or intangible, which is expected to provide benefits to a business.

Assisted Irrigation Investment: (from RA6120.2) "Assisted irrigation investment" means the portion of construction costs of Federal Reclamation projects which are allocated to the irrigation purpose and are assigned pursuant to legal authorization for repayment from the revenues of the power system.

ATC: Available Transmission (or Transfer) Capacity

Automatic Generation Control (AGC): The regulation of electric generator power output within a control area in response to changes in system frequency, time, error, and tie-line loading, so as to maintain the scheduled system frequency and the established interchanges with other areas.

Autotransformer: A transformer which uses a common winding for both the primary and secondary sides. This gives it distinct advantages, both in economy and size, over two-winding power transformers when the transformation ratio is small. For example, an auto-transformer would be used to step up voltages from 230 kilovolts to 345 kilovolts whereas a two-winding power transformer would be used to boost voltages from 13.8 kilovolts to 230 kilovolts.

Auxiliary Equipment (Generating Station): Accessory equipment necessary for generating station operations. This would include pumps, stokers, fans, pulverizers, etc.

Auxiliary Power Supply (Generating Station): The power required to operate generating station auxiliary equipment.

Availability Factor: The ratio of the time a machine or equipment is ready for or in service to the total time interval under consideration.

Available but not Needed Capability: Net capability of main generating units that are operable but not considered necessary to carry load, and cannot be connected to load within 30 minutes.

Average Hydro (Average Water Conditions): Precipitation and runoff conditions which provide water for hydroelectric power generation approximating the most often recurring (mean) amount and distribution over a long time period, usually the entire period of record.

Average Revenue per Kilowatt-hour: The average revenue per kilowatt-hour of electricity sold by sector (residential, commercial, industrial, or other) and geographic area (State, Census division, and National), is calculated by dividing the total monthly revenue by the corresponding total monthly sales for each sector and geographic area.

Aviation Marker Ball: A round, colored ball, usually aviation orange, attached to the conductors or overhead ground wires for daytime marking. Available in various sizes from 9-inch diameter and larger.

Avoided Costs: The costs an electric utility would otherwise incur to generate power if it did not purchase electricity from another source.

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Backbone Transmission System: The principal portion of a transmission system to which other lines connect.

Balancing Account: An account set up to allow periodic balancing of financial transactions that, under normal course of business, do not result in a zero balance of cash inflows and outflows within a specified accounting period.

Balancing Energy Supply: Energy not scheduled in advance that is required to meet energy imbalances in real-time. This energy is supplied by generators under the system operator's control, providing spinning and non-spinning reserves, replacement reserves, and regulation, and other generators able to respond to the system operator's request for more or less energy.

Bare Hand: Live Line Maintenance (see Live Line Maintenance).

Barrel: A volumetric unit of measure for crude oil and petroleum products equivalent to 42 U.S. gallons.

Base Bill: A charge calculated by multiplying the rate from the appropriate electric rate schedule by the consumption level.

Baseload: The minimum amount of electric power delivered or required over a given period of time at a steady rate.(Contrast to Peak Load)

Baseload Generation Capacity: The generating equipment normally operated to serve loads on an around-the-clock basis. Those generating facilities within a utility system which are operated to the greatest extent possible to maximize system mechanical and thermal efficiency and minimize system operating costs.

Baseload Plant (or Unit): A plant, usually housing high efficiency steam-electric units, which is normally operated to take all or part of the minimum load of a system, and which consequently produces electricity at an essentially constant rate and runs continuously. These units are operated to maximize system mechanical and thermal efficiency and minimize system operating costs.

Baseload Power: Power generated to meet the level of electrical demand during all hours of a time period

Basin Fund: Upper Colorado River Basin Fund

Bbl: The abbreviation for barrel.

BBS: Bulletin Board System (electronic data access through FERC)

Bcf: The abbreviation for 1 billion cubic feet.

Betterment: A substantial enlargement or improvement of existing structures, facilities, or equipment by replacement or improvement of parts without replacement of a complete unit of property, which has the effect of extending the useful life of the property, increasing its capacity, lowering its operating cost, or otherwise adding to its worth through the benefit it can yield.

Bilateral Contract: An agreement for the purchase and the sale of energy products and services.

Biomass: Any organic material not derived from fossil fuels. The rules defines “biomass” as a plant materials that are obtained from cultivation, or harvested from naturally occurring vegetation without significant resource depletion. A variety of organic fuel sources which can either be processed into synthetic fuels or burned directly to produce steam or electricity.

Bituminous Coal: The most common coal. It is dense and black (often with well-defined bands of bright and full material). Its moisture content usually is less than 20 percent. It is used for generating electricity, making coke, and space heating. Comprises five groups classified according to the following ASTM Specification D388-84, on a dry mineral-matter-free (mmf) basis for fixed-carbon and volatile matter and a moist mmf basis for calorific value.

LV =Low volatile bituminous coal

MV=Medium volatile bituminous coal

HVA=High volatile A bituminous coal

HVB=High volatile B bituminous coal

HVC=High volatile C bituminous coal

Black Start: See Startup Service

Blackout: The disconnection of the source of electricity from all the electrical loads in a certain geographical area brought about by an emergency forced outage or other fault in the generation/transmission/distribution system servicing the area. A blackout could also be caused by intentional load drops if adequate generation is not available to meet the load. [See Rolling (Rotating) Blackout]

Blackout, Rolling (Rotating): Controlled recurring outages across a region designed to prevent a system disturbance when power demand is greater that the available generation or transmission capacity. "Rolling" or "Rotating" refers to the method that system operators use - disconnecting a certain load area for a time period, then reconnecting it and disconnecting another load area in a subsequent time period.

Boiler: A device for generating steam for power, processing, or heating purposes or for producing hot water for heating purposes or hot water supply. Heat from an external combustion source is transmitted to a fluid contained within the tubes in the boiler shell. This fluid is delivered to an end-use at a desired pressure, temperature, and quality.

Broker: An entity acting as an agent for others in negotiating contracts, purchases, or sales of electrical energy or services without owning any transmission or generation facilities. Such business or party does not take ownership for the power transacted.

Brownout: An intentional reduction of loads in an area by the partial reduction of electrical voltages which results in lights dimming and motor driven devices losing efficiency.

Brush: A stationary conductor, usually carbon, held in contact with a moving conductor. Typically used in electric motors or generators.

Btu (British Thermal Unit): A standard unit for measuring the quantity of heat energy equal to the quantity of heat required to raise the temperature of 1 pound of water by 1 degree Fahrenheit. The fuel content of one btu is roughly equivalent to a kitchen match.

Bulk Delivery Point: A substation that receives power delivered at high voltage. Transformers at these points lower the voltage for power distribution.

Bundle, Conductor: Two or more conductors per phase, in a power transmission line.

Bureau Of Reclamation: Agency within the Department of Interior responsible for operating and maintaining certain hydroelectric powerplants and certain irrigation facilities. BOR and USBR are both abbreviations for the Bureau of Reclamation.

Bus: Generally, a conductor, or group of conductors, that serves as a common connection for two or more circuits. In substations, specifically a conductor, usually rigid, which interconnects equipment of the same voltage. Then, by extension of usage, any rigid conductor.

Busbar: An electrical conductor in the form of rigid bars, located in switchyard or powerplants, serving as a common connection for two or more electrical circuits.

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Cable Miles: The total length of separately sheathed cables, expressed in miles, regardless of the number of conductors contained in a single sheath. For pipe-type cables, it is the total single-conductor mileage.

CAISO: California Independent System Operator - A state chartered organization in California charged with ensuring the reliability of the electric power system.

Calorie: A unit of heat energy equal to the amount of heat that will raise the temperature of one gram of water one degree Celsius.

Capability: The maximum load that a generating unit, generating station, or other electrical apparatus can carry under specified conditions for a given period of time without exceeding approved temperature and stress limits.

Capability Curve: A curve drawn to show the limits of reactive and kilowatt loads that a generator can tolerate without overheating or becoming unstable.

Capability Margin (Reserve Margin): The difference between net system capability and system maximum load requirements (peak load). It is the margin of capability available to provide for scheduled maintenance, emergency outages, system operating requirements, and unforeseen loads. On a regional or national basis, it is the difference between aggregate net system capability of the various systems in the region or nation and the sum of system maximum (peak) loads without allowance for time diversity between the loads of several systems. However, within a region, account is taken of diversity between peak loads of systems that are operated as a closely coordinated group.

Capability, Emergency: The gross unit or plant output corresponding to the net demonstrated capability, and includes auxiliary use power. Units or plants may be operated at these ratings only in an emergency.

Capability, Gross System: The total net generating station capability of a system at a stated period of time (usually at the time of the system's maximum load), plus capability available at such time from other sources through firm power contracts.

Capability, Peaking: Generating capability normally designed to use only during the maximum load period of a designated time interval.

Capacitor (Cap.): A device to store an electrical charge. It usually consists of two conductors separated by a non conductor (dielectric) such as glass, paper, air, oil, or mica. A capacitor will not pass direct current; its impedance for alternating current frequencies is inversely proportional to frequency.

Capacitor Bank: A grouping of capacitors used to maintain or increase voltage in power lines and to improve system efficiency by reducing inductive losses which waste energy.

Capacity: The amount of electric power delivered or required for which a generator, turbine, transformer, transmission circuit, station, or system is rated by the manufacturer. The rate of delivery of electricity measured in kilowatts or megawatts.

Capacity, Assured System: The dependable capacity of system facilities available for serving system load after allowance for required reserve capacity, including the effect of emergency interchange agreements and firm power agreements with other systems.

Capacity, Base Load: see Baseload Generation Capacity

Capacity Charge: An element in a two-part pricing method used in capacity transactions (energy charge is the other element). The capacity charge, sometimes called Demand Charge, is assessed on the amount of capacity being purchased. The capacity charge is sometimes expressed in units of $/kW/month .

Capacity, Contingent: Capacity sold to customers with the understanding that the service may be unavailable under certain conditions.

Capacity Component: Part of a firm-power rate; shown in the power repayment study (PRS) as a dollar per kW per year charge. Billed on a dollar per kW per month basis. Applied each billing period to each kW which each contractor is entitled to by contract.

Capacity, Dependable: The load-carrying ability of a station or system under adverse conditions for the time interval and period specified when related to the load characteristics to be supplied. Dependable capacity of a system includes net firm power purchases.

Capacity Factor: The fraction or percentage of total energy delivered from a resource over a period of time, divided by the maximum that could have been delivered if the resource was used at its maximum capacity over the entire period.

Capacity, Hydraulic: The rating of a hydroelectric generating unit or the sum of such ratings for all units in a station or stations.

Capacity, Installed: The total of the capacities as shown by the nameplates of similar kinds of apparatus such as generating units, turbines , synchronous condensers, transformers, or other equipment in a station or system.

Capacity, Nameplate: The nominal rated capacity of a generating unit or other similar apparatus. The term gives an indication of the approximate generating capacity of the unit, but in many cases the unit is capable of generating on a continuous basis substantially more than the nameplate capacity.

Capacity, Overload: The maximum load that a machine, apparatus, or device can carry for a specified time period under specified conditions when operating beyond its nameplate rating but within the limits of the manufacturer's guarantee and within the safe limits determined by the owner. For example, most of the generators installed in newer hydroelectric plants have a continuous overload capacity of 115 percent of the nameplate capacity.

Capacity, Peaking: Generating equipment normally operated only during the hours of highest daily, weekly, or seasonal loads. Some generating equipment may be operated at certain times as peaking capacity and at other times to serve loads on a round-the-clock basis.

Capacity, Purchased: The amount of energy and capacity available for purchase from outside the system.

Capacity Rate:See Capacity Charge.

Capacity, Reserve Generating: Extra generating capacity available to meet unanticipated power demands or to generate power in the event of generation loss resulting from scheduled or unscheduled outages of regularly used generating capacity.

Capacity, Reserve System: The difference between dependable system capacity, including net firm power purchases, and the actual or anticipated peak load for a specified period.
Cold: Thermal generating units available for service but not maintained at operating temperature.
Hot: Thermal generating units available, up to temperature and ready for service, although not actually in service.
Spinning: Generating units connected to the bus and ready to take load or operating below rated level.

Capacity, Thermal: The rating of a thermal electric generating unit or the sum of such ratings for all units in a station or stations.

Capital (Financial): The line items on the right side of a balance sheet that include debt, preferred stock, and common equity. A net increase in assets must be financed by an increase in one or more forms of capital.

Cascading Outages: A connected series of uncontrolled outages that resembles dominos falling one after another.

Cathode Ray Tube (CRT): The picture tube on a TV set. Technically a tube in which an electron beam can be focused on luminescent particles on a screen and varied in position and intensity to produce a visible pattern.

CBM: Capacity Benefit Margin

Ccf: One hundred cubic feet. Used as a measure of residential natural gas usage.

CDP: Customer Displacement Power. A replacement option under the Amendment to SLCA/IP firm electric service contract.

cfs: Cubic feet per second

  • 1 cfs for 1 minute = 449 gallons
  • 1 cfs for 24 hours = 646,272 gallons
  • 1 cfs for 24 hours = 1.983 acre feet
  • 1 cfs for 7 days = 13.881 acre feet
  • 1 cfs for 30 days = 59.5 acre feet
  • 1 cfs for 1 year = 724 acre feet

Charge, Demand: That portion of the charge for electric service based upon the customer's billing demand under an applicable rate schedule or contract.

Circuit: A conductor or a system of conductors through which electric current flows or is intended to flow.

Circuit Miles of Electric Line: The total length in miles of separate circuits, not including customer's services, whether one, two, three, four or more conductors per circuit.

Circuit Breaker: Generally, any switching device that is capable of closing under normal load conditions or interrupting an electrical circuit under overload or short circuit conditions.

Circuit Recloser: A line protective device which interrupts momentary line faults. In addition, it restores power automatically when the fault is cleared.

Class Of Service: Type of power sold to customers (i.e., firm power and energy, non-firm power and energy, peaking power - with or without energy, emergency service, maintenance service, fuel replacement service, etc.).

Clearance: A statement with documentation from the operations supervisor to the job supervisor declaring that all equipment to be worked on has been de-energized and has been isolated from hazardous sources of energy.

Clearance Requirements: Distances required between conductors of various voltages and the ground; also, the distance required between the line and trees, buildings, and other objects on, above, or immediately adjacent to the right-of-way.

Closed (versus Open): When referring to a circuit breaker or other switching device, closed means that the switch contacts are together, the switch is on and current has a flow path. OPEN means the switch contacts are apart, the switch is off, and current cannot flow.

CME: Capitalized movable equipment.

Coal: A black or brownish-black solid combustible substance formed by the partial decomposition of vegetable matter in the absence of air. The rank of coal, which includes anthracite, bituminous coal, subbituminous coal, and lignite, is based on fixed carbon, volatile matter, and heating value. Coal rank indicates the progressive alteration from lignite to anthracite. Lignite contains approximately 9 to 17 million Btu per ton. The contents of subbituminous and bituminous coal range from 16 to 24 million Btu per ton and from 19 to 30 million Btu per ton, respectively. Anthracite contains approximately 22 to 28 million Btu per ton.

Co-generation: Producing both electric energy and steam from various energy sources.

Cogenerator: A generating facility that produces electricity and another form of useful thermal energy (such as heat or steam) used for industrial, commercial, heating, or cooling purposes. To receive status as a qualifying facility (QF) under the Public Utility Regulatory Policies Act (PURPA), the facility must produce electric energy and "another form of useful thermal energy through the sequential use of energy," and meet certain ownership, operating, and efficiency criteria established by the Federal Energy Regulatory Commission (FERC). (See the code of Federal Regulations, Title 18, Part 292.)

Coil: One or more wound insulated conductors arranged to produce an electromagnetic force. Used in electro-mechanical protective relays and rotating electrical machinery in power systems as well as devices which provide inductances in electronics and power systems.

Coincidental Demand: The sum of two or more demands that occur in the same time interval.

Coincidental Peak Load: The sum of two or more peak loads that occur in the same time interval.

Coke (Petroleum): A residue high in carbon content and low in hydrogen that is the final product of thermal decomposition in the condensation process in cracking. This product is reported as marketable coke or catalyst coke. The conversion factor is 5 barrels (42 U.S. gallons each) per short ton.

Cold Shutdown: Refers to the situation when the boiler working fluid or the coolant water in a nuclear reactor is below the boiling point and the pressure is reduced to atmospheric levels.

Collbran: Collbran Project, a Federal multipurpose water project located in western Colorado near Grand Junction.

Collection Ring: A metal ring suitably mounted on an electric machine that conducts current into and out of the rotating member.

Combined Cycle: An electric generating technology in which electricity is produced from otherwise lost waste heat exiting from one or more gas (combustion) turbines. The exiting heat is routed to a conventional boiler or to a heat recovery steam generator for use by a steam turbine to produce electricity. This process increases the efficiency of the electric generating unit.

Combined Cycle Unit: An electric generating unit that consists of one or more combustion turbines and one or more boilers with a portion of the required energy input to the boiler(s) provided by the exhaust gas of the combustion turbine(s).

Combined Pumped-Storage Plant: A pumped-storage hydroelectric power plant that uses both pumped water and natural streamflow to produce electricity.

Commercial: The commercial sector is generally defined by electric utilities as nonmanufacturing business establishments, including hotels, motels, restaurants, wholesale businesses, retail stores, and health, social, and educational institutions. The utility may classify commercial service as all consumers whose demand or annual use exceeds some specified limit. The limit may be set by the utility based on the rate schedule of the utility.

Commercial Operation: Commercial operation begins when control of the loading of the generator is turned over to the system dispatcher.

Commission: The Federal Energy Regulatory Commission.

Committed Load: The load that has been accepted to be served either in the day-ahead or hour-ahead bidding process.

Common Costs: Costs that are incurred jointly for two or more types of operations and are subsequently allocated to each such operation (electric, gas, water, etc.) usually on the basis of the relative percentages of utility plant, revenue, or use of space.

Common Plant: Utility Plant used by a utility company which renders more than one utility service, such as electric and gas, to such an extent and in such a manner as to render segregation impractical, as would be the case with a garage housing electric and gas utility trucks, or where one facility such as coal handling or water treatment is provided to serve the combined boiler plant.

Commutator: In an electrical motor or generator, a ring of insulated copper segments connected to the rotating armature windings, and on which brushes make contact.

Composite Rate: The rate for commercial firm power and is the total annual revenue requirement for capacity and energy divided by the total annual energy sales. It is expressed in mills/kWh and used for comparison purposes.

Condenser: A large heat exchanger designed to cool exhaust steam from a turbine below the boiling point so that it can be returned to the heat source as water. (In a pressurized water reactor, the water is returned to the steam generator. In a boiling water reactor, it returns to the reactor core.) The heat removed from the steam by the condenser is transferred to a circulating water system and is exhausted to the environment, either through a cooling tower or directly into a body of water. A condenser is also another name for a Capacitor.

Conductor: The wire cable strung between transmission towers through which the electric current flows. More generally, any object (wire, cable, bus) that conducts electric current.

Conductor, Bundled: Two or more conductors per phase of a transmission line. Bundling conductors allows each phase of a transmission line to conduct more current than would a single conductor.

Conductor, Single: One conductor used per phase.

Conduit Bank: A length of one or more underground conduits or ducts (whether or not enclosed in concrete) designed to contain underground cables. A gallery or cable tunnel for power cables is generally treated as conduit bank for property reporting purposes.

Conduit Bank Miles: Miles of conduit bank, regardless of number of conduits or ducts, of all sizes and types, and including manholes and handholes.

Connection: The physical connection (e.g. transmission lines, transformers, switch gear, etc.) between two electric systems permitting the transfer of electric energy in one or both directions.

Conservation and Other DSM: This Demand-Side Management category represents the amount of consumer peak load reduction at the time of system peak due to utility programs that reduce consumer load during many hours of the year. Examples include utility rebate and shared savings activities for energy efficient appliance installation, lighting and electrical machinery, and weatherization materials. In addition, this category includes all other Demand-Side Management activities, such as thermal storage, time-of-use rates, fuel substitutions, measurement and evaluation, and any other utility-administered Demand-Side Management activity designed to reduce demand and/or electricity use.

Constant Current Transformer: A transformer which, when supplied from a constant potential source, automatically maintains a constant current in its secondary under varying load conditions.

Constraints: Physical and operational limitations in electrical power transfer through transmission facilities. Physical, hydrological, operational, and environmental limitations in electrical power generation at hydroelectric facilities.

Construction Work In Progress (CWIP): The balance shown on a utility's balance sheet for construction work not yet completed but in process. This balance line item may or may not be included in the rate base.

Consumer: A customer who purchases power for personal use.

Consumption (Fuel): The amount of fuel used for gross generation, providing standby service, start-up and/or flame stabilization.

Contingency: The unexpected failure or outage of a system component, such as a generator, transmission line, circuit breaker, switch, or other electrical element. A contingency also may include multiple components, which are related by situations leading to simultaneous component outages.

Contingency Reserve: The portion of Operating Reserve - Spinning and Supplemental that is allocated to respond to Disturbances.

Contingency Reserve Restoration Period: The time after the end of the Disturbance Recovery Period in which Contingency Reserves must be re-established fully.

Contract Demand: The amount of power (in kilowatts) that an electric service supplier agrees to make continuously available for delivery to a particular consumer and that the consumer agrees to purchase.

Contract Price: Price of fuels marketed on a contract basis covering a period of one or more years. Contract prices reflect market conditions at the time the contract was negotiated and therefore remain constant throughout the contract life or are adjusted through escalation clauses. Generally, contract prices do not fluctuate widely.

Contract Rate Of Delivery (CROD): Firm capacity (kW) the electric service supplier agrees to have available for delivery. It may or may not be accompanied by energy. Synonymous with Contract Demand.

Contract Receipts: Purchases based on a negotiated agreement that generally covers a period of one or more years.

Control Area: An electric power system or combination of electric power systems, bounded by interconnection metering and telemetry, to which a common automatic control scheme is applied in order to:

  1. match, at all times, the power output of the generators within the electric power system(s) and capacity and energy purchased from entities outside the electric power system(s), with the load in the electric power system(s);
  2. maintain, within the limits of Good Utility Practice, scheduled interchange with other Control Areas;
  3. maintain the frequency of the electric power system(s) within reasonable limits in accordance with Good Utility Practice;
  4. and provide sufficient generating capacity to maintain operating reserves in accordance with Good Utility Practice.

Control Center: A station from which one or more powerplants are remotely controlled. See also Control Room.

Controller: A device or group of devices that serves to govern, in some predetermined manner, the electric power delivered to the apparatus to which it is connected. Sometimes also referred to as a demand controller.

Control Room: The center where a powerplant is operated, monitored, and controlled (Federal requirements call for a minimum of two licensed operators on duty at all times in a nuclear powerplant control room.) See also Control Center.

Conventional Fuels: The fossil fuels: coal, oil, and natural gas.

Conventional Hydroelectic Plant: A hydroelectric plant that utilizes stream flow only once as it passes downstream, as opposed to a pumped-storage plant which recirculates all or a portion of the streamflow in the production of power.

Converter: A device that changes alternating current power to direct current power or vice versa, or changes one frequency to another.

Converter Station: The assemblage of equipment used to convert alternating current to direct current or vice-versa in a power system.

Coolant: A fluid, usually water, used to cool a nuclear reactor and transfer heat energy. The water also moderates, or slows down, the neutrons used for the fissioning of uranium.

Cooling System: An energy efficiency program promotion aimed at improving the efficiency of the cooling delivery system, including replacement, in the residential, commercial, or industrial sectors.

Cooling Tower: A heat exchanger designed to cool water that was used to cool exhaust steam exiting the power plant turbines. Cooling towers transfer exhaust heat into the air instead of into a body of water.

Cooperative Electric Utility: An electric utility legally established to be owned by and operated for the benefit of those using its service. The utility company will generate, transmit, and/or distribute electrical power to a specified service area not being serviced by another utility. Such ventures are generally exempt from Federal income tax laws. Most electric cooperatives have been initially financed all or in part by loans from the Rural Utilities Services, U.S. Department of Agriculture.

Coordination: The practice by which two or more interconnected electric power systems augment the reliability of bulk electric power supply by establishing planning and operating standards; by exchanging pertinent information regarding additions, retirements, and modifications to the bulk electric power supply system; and by jointly reviewing these changes to assure that they meet the predetermined standards.

Corona: A luminous electrical discharge on a transmission line. Corona appears when the air adjacent to the conductor ionizes due to the applied potential exceeding a certain value. It can be seen as bluish tufts or streamers surrounding the conductor, and generally a hissing sound can be heard. Transmission line corona varies with atmospheric conditions, being more intense during wet weather on A.C. lines. On D.C. lines, audible noise occurs during clear dry weather.

Cost: The amount paid to acquire resources, such as plant and equipment, fuel, or labor services.

Cost Evaluation Period: (from RA6120.2) "Cost evaluation period" means a period of time during which estimates of future costs and revenues may be modified to reflect changing conditions, normally 5 years.

Cost Recovery Criteria: (from RA6120.2) The current rates for a power system will be adequate if, and only if, a power repayment study indicates that:
a. The expected revenues are at least sufficient to recover annually, except for a possible initial short transition period:

  1. All costs of operating and maintaining the power system during the year in which such costs are incurred; plus,
  2. The cost of acquiring power through purchase and/or exchange agreements, the costs for transmission services, and other costs during the year in which such costs are incurred; plus,
  3. Expensed interest on the unamortized investment in Federal power facilities in the year for which the interest charges are assessed, except that recovery of the annual interest expense may be deferred in unusual circumstances for short periods of time; plus,
  4. Interest and amortization of revenue bonds where PMAs are authorized to issue such bonds.

b. In addition to the recovery of the above costs on a year-by-year basis, the expected revenues are at least sufficient to recover:

  1. Each dollar of power investment at Federal hydroelectric generating plants within 50 years after they become revenue producing, except as otherwise provided by law: plus,
  2. Each annual increment of Federal transmission investment within the average service life of such transmission facilities or within a maximum of 50 years, whichever is less; plus,
  3. The cost of each replacement of a unit of property of a Federal power system within its expected service life up to a maximum of 50 years; plus,
  4. Each dollar of assisted irrigation investment within the period established for the irrigation water users to repay their share of construction costs; plus,
  5. Other costs such as payments to basin funds, participating projects or States.

Cost Shifting: A cost transfer from one customer class to another, or from one utility to another. This is considered good when costs are being shifted from you to someone else, and bad when they are being shifted from someone else to you.

CPS - Control Performance Standard: CPS defines a standard of minimum control performance. Each control area is to have the best operation above this minimum that can be achieved within the bounds of reasonable economic and physical limitations. Each control area shall monitor its performance on a continuous basis against two standards: CPS1 and CPS2.

  • CPS1 - Control Performance Standard 1: Over a year, the average of the clock-minute averages of a control area's ACE shall be less than a specific limit. This limit is a constant derived from a target frequency bound reviewed and set as necessary by the NERC Resources Subcommittee.
  • CPS2 - Control Performance Sstandard 2: The average ACE for each six ten-minute period during the hour (i.e., 10, 20, 30, 40, 50 and 60 minutes after the hour) must be within specific limits referred to as L10.

CREDA: Colorado River Energy Distributors Association

Critical Head or Design Head: The head at which the full-gate output of the hydro turbine equals the name-plate generator capacity.

Critical Hydro Period: Period when the limitations of hydroelectric power supply due to water conditions that are most critical with respect to system load requirements.

CROD: See Contract Rate Of Delivery.

Crossarm: The crossing member(s) of a wood pole or steel tower which support the insulators for the conductor.

CRSP: Colorado River Storage Project, a Federal multipurpose water project with facilities located in the upper Colorado River basin states of Arizona, Colorado, New Mexico, Utah, and Wyoming.

CRSP Act: Act of April 11, 1956, ch. 203, 70 Stat. 105, as amended, 43 U.S.C. 620-6200.

CRSP-MC: The Colorado River Storage Project - Management Center; Western office located in Salt Lake City, UT.

CT: see Current Transformer

CT/VT: Current transformers/ voltage transformers

CUP: Central Utah Project, a Bureau of Reclamation water project located in (you guessed it) central Utah. CUP is a participating project of the CRSP.

Current (Electric): A flow of electrons in an electrical conductor. The strength or rate of movement of the electricity is measured in amperes. A generic term usually modified by an adjective (i.e., AC or DC), the amount of electrical charge flowing through a conductor, as compared to Volts , which is the force that drives the electrical charge.

Current Transformer (CT): A small transformer used to convert high currents to low currents. Used to produce a signal that can be measured by meters, relays, or control equipment.

Customer/Account: An entity or person which purchases and is billed for power and energy and other utility related services some time during the period under consideration.

Customer Brochure: A document prepared for public distribution explaining the background and purpose of the rate proposal.

Cycle: In one cycle of alternating electric current, the current goes from zero potential or voltage to a maximum in one direction, back to zero, then to a maximum in the other direction, and then back to zero. A complete sequence of a wave pattern that recurs at regular intervals. The number of cycles occurring in one second is the frequency of the wave. (Direct current [DC] does not fluctuate from positive to negative and hence cycles or frequency can apply only to alternating current [AC].)

Cycling Units: Units which operate with rapid load changes, frequent starts and stops but generally at somewhat lower efficiencies and higher operating costs than base load plants. These units are generally either former base-load units relegated to cycling units or newly built units at a lower megawatt rating which require less capital investment per unit of output than required for base load units. Contrast with Base Load Unit/Station.

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Day-Ahead Market: The forward market for the supply of electrical power at least 24 hours before delivery to Buyers and End-Use Customers.

DCS: Disturbance Control Standard - Disturbance Control Standard is part of the Control Performance Standards. DCS is designed to judge the performance of a Control Area following a reportable disturbance, by evaluating the use of the Control Area's Contingency Reserves.

Dead-End Tower: See Tower, Dead-End

Declining Block Rate: A pattern of unit charges within a customer class that assesses a lower unit charge on additional blocks of demand and/or energy purchases as usage increases.

Degree Day: A unit measuring the extent to which the outdoor mean (average of maximum and minimum) daily dry bulb temperature falls below (in the case of heating) or rises above (in the case of cooling) an assumed base. The base is normally taken as 65° F for heating and cooling unless otherwise designated. One degree-day is counted for each degree of deficiency below (for heating) or excess over (for cooling) the assumed base, for each calendar day on which such deficiency or excess occurs.

Delivering Party: The entity supplying the capacity and/or energy to be transmitted at Point(s) of Receipt.

Demand: In economics usage, the quantity of a product that will be purchased at a given price at a particular point in time. In an electric utility context, the rate at which electric energy is delivered to or by a system over any designated period of time.

Demand, Annual Maximum: The greatest of all demands or the load under consideration which occurred during a prescribed demand interval in a calendar year.

Demand, Annual System Maximum: The greatest demand on an electric system or any of its parts over any prescribed interval of time in a given calendar year.

Demand, Average: The demand on, or the power output of an electric system or any of its parts over any interval of time, as determined by dividing the total number of kilowatt-hours by the number of units of time in the interval

Demand, Billing: The demand upon which billing to a customer is based, as specified in a rate schedule or contract. It may be based on the contract year, a contract minimum, or a previous maximum and, therefore, does not necessarily coincide with the actual measured demand of the billing period.

Demand Charge: That portion of the charge for electric service based upon the electric capacity (kW or KVA) consumed and billed on the basis of billing demand under and applicable rate schedule.

Demand, Coincident: The sum or two or more demands which occur in the same demand interval.

Demand Factor: The ratio of the maximum demand of a system, or part of a system, to the total connected load of the system, or part of the system, under consideration.

Demand, Instantaneous Peak: The maximum demand at the instant of greatest load, usually determined from the readings of indicating or graphic meters.

Demand, Integrated: The demand usually determined by an integrating demand meter or by the integration of a load curve. It is the summation of the continuously varying instantaneous demands during a specified demand interval.

Demand Interval: The period of time during which the electric energy flow is integrated in determining demand, such as 60-minute, 30-minute, or instantaneous.

Demand, Non-coincident: The sum or two or more individual demands which do not occur in the same demand interval. Meaningful only when considering demands within a limited period of time, such as day, week, month, heating or cooling season, and usually for not more than a year.

Demand-Side Management: The planning, implementation, and monitoring of utility activities designed to encourage consumers to modify patterns of electricity usage, including the timing and level of electricity demand. It refers only to energy and load-shape modifying activities that are undertaken in response to utility-administered programs. It does not refer to energy and load-shape changes arising from the normal operation of the marketplace or from government-mandated energy efficiency standards. Demand-Side Management (DSM) covers the complete range of load-shape objectives, including strategic conservation and load management, as well as strategic load growth.

Demand-Side Management Costs: The costs incurred by the utility to achieve the capacity and energy savings from the Demand-Side Management Program. Costs (expenditures) incurred by consumers or third parties are to be excluded. The costs are to be reported in nominal dollars in the year in which they are incurred, regardless of when the savings occur. Program costs include expensed items incurred to implement the program, incentive payments provided to consumers to install Demand-Side Management measures, and annual operation and maintenance expenses incurred during the year. Utility costs that are general, administrative, or not specific to a particular Demand-Side Management category are to be included in "other" costs.

Department of Energy (DOE): An agency established in 1977 by the Department of Energy Organization Act to consolidate the major Federal energy functions into one cabinet level department that would formulate a comprehensive, balanced national energy policy. DOE is responsible for a variety of regulatory, research, and marketing programs related to energy production and use. Numerous laboratories and test sites are involved in these projects.

Design Voltage: The nominal voltage for which a line or piece of equipment is designed. This is a reference level of voltage for identification and not necessarily the precise level at which it operates.

Designated Agent: Any entity that performs actions or functions on behalf of the Transmission Provider, an eligible Customer or the Transmission Customer required under the Tariff.

Direct Access: The right for a Generator to engage in a Bilateral Contract with a Buyer.

Direct Access Generation: The generation output which is used to meet the demand of Bilateral Contracts.

Direct Access Demand: The energy consumption met under Bilateral Contracts who are eligible to select their supplier of electric power.

Direct Current (DC): Term applied to an electric current or voltage which may have pulsating characteristics, but which does not reverse direction.

Direct Load Control: Refers to utility programs that can interrupt consumer load at the time of annual peak load by direct control of the utility system operator by interrupting power supply to individual appliances or equipment on consumer premises. This type of control usually involves residential consumers. Direct Load Control excludes Interruptible Load and Other Load Management effects. (Direct Load Control, as defined here, is synonymous with Direct Load Control Management reported to the North American Electric Reliability Council on the voluntary Office of Energy Emergency Operations Form OE-411, "Coordinated Regional Bulk Power Supply Program Report," with the exception that annual peak load effects are reported here and seasonal (i.e., summer and winter) peak load effects are reported on the OE-411).

Direct Utility Cost: A utility cost that is identified with one of the DSM program categories (i.e., Energy Efficiency, Direct Load Control, Interruptible Load, Other Load Management, Other DSM Programs, Load Building).

Disconnecting Switch: A power system device used to open a circuit in which only a negligible amount of current, or no current is flowing. Disconnecting switches are manually or motor operated, and are used to isolate relatively unloaded equipment. Air is the usual insulating medium between the contacts in the open position.

Dispatch: The operating control of an integrated electric system to 1) assign generation of specific generating stations and other sources of supply to effect the most reliable and economical supply as the total of the significant area loads rises or falls; 2) Control operations of high-voltage lines, substation, and equipment; 3) operate the interconnect; and 4) schedule energy transactions with other interconnected electric utilities.

Dispatcher: One of a number of people at a Dispatch Center who monitor and control a power system. At the Western control centers, responsibilities of the dispatchers include the following:

  1. Operation of the Automatic Generation Control equipment to regulate the loading of the generators in the Federal powerplants to help maintain scheduled System Frequency and the scheduled power interchange with other utilities.
  2. The source of authority for issuance of all electrical Clearances on the Western system for safe maintenance and repair of equipment.
  3. The location and isolation of system trouble and dispatching of maintenance forces to expedite repair of facilities and restoration of service, for security of the system.
  4. Surveillance and maintenance of the transmission voltage schedules.
  5. The Western employee in charge of the system switching function at a Dispatch Office.

Dispatch Center: A room located in a transmission or distribution System Control Center which contains the display and control devices used by Dispatchers to monitor and control the power system.

Dispatching: The operating control of an integrated electric system involving operations such as:

  1. The assignment of load to specific generating station and other sources of supply to effect the most reliable and economical supply as the total of the significant area loads rises or falls.
  2. The control of operations with maintenance of high-voltage lines, substations, and equipment.
  3. The operation of principal tie lines and switching.
  4. The scheduling of energy transactions with connecting electric utilities.

Distillate Fuel Oil: A general classification for one of the petroleum fractions produced in conventional distillation operations. It is used primarily for space heating, on-and-off-highway diesel engine fuel (including railroad engine fuel and fuel for agriculture machinery), and electric power generation. Included are Fuel Oils No. 1, No. 2, and No. 4; and Diesel Fuels No. 1, No. 2, and No. 4.

Distribution: The act or process of distributing electric energy from convenient points on the transmission or bulk power system to consumers. Also a functional classification relating to that portion of utility facilities used for the purpose of delivering electric energy from convenient points on the transmission system to consumers, or to expenses relating to the operation and maintenance of distribution plant.

Distribution Line: One or more circuits of a distribution system on the same line of poles or supporting structures, operating at relatively low voltage compared with transmission lines.

Distribution Panel: An electric panel with circuit breakers which energizes the other panels or circuits.

Distribution System: In power system usage, the transport of electricity to ultimate usage points such as homes and industries directly from nearby generators or from interchanges with higher voltage transmission networks which transport bulk power over longer distances from large generation centers.

Disturbance: Any occurrence that adversely affects normal power flow in a system, such as lightning surge on a line, or a short circuit.

Disturbance Recovery Criterion: The ACE (or its equivalent) behavior that must be observed within the Disturbance Recovery Period to be compliant with the Disturbance Control Standard.

Disturbance Recovery Period: The time after the start of a Disturbance in which the Disturbance Recovery Criterion shall be met for compliance with the NERC Disturbance Control Standard (DCS).

Diversity: The characteristic of a variety of electric loads whereby individual maximum demands usually occur at different times. Diversity among customer loads results in diversity among the loads of distribution transformers, feeders, and substations, as well as between entire systems. Also known as Load Diversity.

Diversity Exchange: An exchange of capacity or energy, or both, between systems whose peak loads occur at different times of the day or seasons of the year.

Diversity Factor: The ratio of the sum of the noncoincident maximum demands of the various subdivisions of a system, or part of a system, to the maximum demand of the whole system, or part under consideration.

DOE: United States Department of Energy.

DOE Order RA 6120.2: An order dealing with power marketing administration financial reporting and rate-making procedures. See RA6120.2.

Double Circuit: The placing of two separate electrical circuits (for alternating current, each consisting of three separate conductor or bundles of conductors) on the same row of towers.

DPR: Definite Plan Report, a Bureau of Reclamation document outlining the development of a water project.

Drawdown: The distance that the water surface of a reservoir is lowered from a given elevation as the result of the withdrawal of water for generation or irrigation.

DSM: See Demand Side Management

DSWR: The Desert Southwest Region of the Western Area Power Administration.

Dual Rate, Double Rate or Two Rate Watthour Meter: A watthour meter with two registers constructed so that the on-peak and off-peak energy (kilowatthours) will be indicated on a separate set of dials. The switch from one register to the other is controlled by an internal time switch or by an external signal that may be actuated by a local device or by a device located at a remote location. Carryover may be accomplished by battery or spring storage or photocell synchronization.

Dynamic Transfer: The provision of the real-time monitoring, telemetering, computer software, hardware, communications, engineering, energy accounting (including inadvertent interchange), and administration required to implement a Dynamic Schedule, Pseudo-Tie or Supplemental Regulation Service.

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EA: See Environmental Assessment

Easement: The right, privilege, or interest obtained by Western through condemnation or legal conveyance to construct, maintain, and operate transmission facilities within a tract of land (see Right-of-Way).

Economic Dispatch: The centralized coordinated decision to use generating resources to serve load in the most economic manner.

Eddy-Current Loss: Loss in the iron core of a transformer due to currents being induced in and flowing around core. Also induced in conductors where it causes heating.

EHV: See Extra High Voltage

EIS: See Environmental impact statement.

Electric Capacity: The rated continuous load-carrying ability, expressed in megawatts (MW) or megavolt-amperes (MVA) of generation, transmission, or other electrical equipment.

Electric Energy: The generation or use of electric power by a device over a period of time, expressed in kilowatt-hours (kWh), megawatt-hours (MWh), or gigawatt-hours (GWh).

Electric Plant (Physical): A facility containing prime movers, electric generators, and auxiliary equipment for converting mechanical, chemical, and/or fission energy into electric energy.

Electric Rate: The unit prices and the quantities to which they apply as specified in an electric rate schedule or sales contract.

Electric Rate Schedule: A statement of the electric rate and the terms and conditions governing its application, including attendant contract terms and conditions that have been accepted by a regulatory body with appropriate oversight authority.

Electric Utility: A corporation, person, agency, authority, or other legal entity or instrumentality that owns and/or operates facilities within the United States, its territories, or Puerto Rico for the generation, transmission, distribution, or sale of electric energy primarily for use by the public and files forms listed in the Code of Federal Regulations, Title 18, Part 141. Facilities that qualify as cogenerators or small power producers under the Public Utility Regulatory Policies Act (PURPA) are not considered electric utilities.

Electric Utility Indutry: All enterprises engaged in the production and/or distribution of electricity for use by the public, including investor owned, cooperatively owned, and government-owned electric utilities (the latter includes municipal systems, Federal agencies, state projects, and public power districts), and, where the data are not separable, those industrial plants contributing to the public supply.

Electromagnetic: Of or pertaining to the magnetic forces produced in a surrounding medium by the flow of current in a circuit.

Electromagnetic Radiation: A travelling wave motion resulting from changing electric or magnetic fields. Familiar electromagnetic radiations range from x-rays (and gamma rays) of short wavelength, through the ultraviolet, visible, and infrared regions, to radar (microwave) or radio waves of relatively long wavelength. All electromagnetic radiations travel in a vacuum with the velocity of light.

Electron: An elementary particle with a unit negative charge. Electrons surround the positively charged nucleus and determine the chemical properties of the atom.

Embedded Cost: Monies already spent for investment in plant and operating expenses. Embedded cost may be adjusted or normalized on the basis of known changes that occur during the period under consideration. For example, a new labor contract executed during the period under consideration would further increase labor costs by a known amount. On the other hand, when it is known that certain expenses will not recur in the near future, those expenses should not be considered embedded costs.

Emergency: Any abnormal system condition which required immediate manual or automatic action to prevent loss of load, equipment damage, or tripping of system elements which might result in cascading and to restore system operation to meet the Minimum Operating Reliability Criteria.

Emergency Assistance Energy: Energy delivered to other utilities in situations of unplanned, forced outages to their generation or transmission facilities.

Emergency notice: A notice issued by the CAISO when the system reliability of the CAISO controlled grid is in danger of instability, voltage collapse, or under-frequency caused by transmission or generation trouble in the CAISO control area, or events outside of the CAISO control area that could result in a cascade of events throughout the WSCC grid.

  • Stage 1: Actual or anticipated operating reserves are less than WSCC minimum operating reserve criteria.
  • Stage 2: Actual or anticipated operating reserves are less than or equal to five percent (5%).
  • Stage 3: Actual or anticipated operating reserves are less than or equal to 1 1/2%

EMS: see Energy Management System

Encoder: A device which converts a meter reading into a form suitable for communicating to a remote central location or portable recording device.

End-Use Customer: A residential, commercial, agricultural, or industrial customer in the electric industry who buys electric power to be consumed as a final product (not for resale).

Energized System (or Facilities) : A system under load (supplying energy to load) or carrying rated voltage and frequency, but not supplying load.

Energy: The capacity for doing work as measured by the capability of doing work (potential energy) or the conversion of this capability to motion (kinetic energy). Energy has several forms, some of which are easily convertible and can be changed to another form useful for work. Most of the world's convertible energy comes from fossil fuels that are burned to produce heat that is then used as a transfer medium to mechanical or other means in order to accomplish tasks. Electrical energy is usually measured in kilowatthours or megawatthours, while heat energy is usually measured in British thermal units (BTU) or joules.

Energy Charge: That portion of the charge for electric service based upon the electric energy (kWh) consumed or billed. The charge is generally expressed as a mills/kWh, ¢/kWh, or $/MWh value.

Energy Component: Part of a firm power rate; expressed in mills per kilowatt-hour (kWh). Applied to each kWh made available to each customer.

Energy Conservation: The more efficent use of energy resources. Energy conservation seeks to reduce energy invested per unit of product output, service performed, or benefit received through waste reduction. Energy conservation and energy use reduction are not synonymous.

Energy Costs: Costs, such as for fuel, that are related to and vary with energy production and consumption.

Energy Deliveries: Energy generated by one electric utility system and delivered to another system through one or more transmission lines.

Energy, Dump: Energy generated in hydroelectric plants by water that cannot be stored or conserved and which energy is in excess of the needs of the electric system producing the energy.

Energy, Economy: Energy produced and supplied from a more economical source in one system, for that being produced or capable of being produced by a less economical source in another system (e.g., hydroelectric for oil fired generation).

Energy Effects: The changes in aggregate electricity use (measured in megawatthours) for customers that participate in a utility DSM program. Energy Effects should represent changes at the consumer meter (i.e., exclude transmission and distribution effects) and reflect only activities that are undertaken specifically in response to utility-administered programs, including those activities implemented by third parties under contract to the utility. To the extent possible, Energy Effects should exclude non-program related effects such as changes in energy usage attributable to nonparticipants, government-mandated energy efficiency standards that legislate improvements in building and appliance energy usage, changes in consumer behavior that result in greater energy use after initiation in a DSM program, the natural operations of the marketplace, and weather and business cycle adjustments.

Energy Efficiency: Refers to programs that are aimed at reducing the energy used by specific end-use devices and systems, typically without affecting the services provided. These programs reduce overall electricity consumption (reported in megawatthours), often without explicit consideration for the timing of program-induced savings. Such savings are generally achieved by substituting technically more advanced equipment to produce the same level of end-use services (e.g. lighting, heating, motor drive) with less electricity. Examples include high-efficiency appliances, efficient lighting programs, high-efficiency heating, ventilating and air conditioning (HVAC) systems or control modifications, efficient building design, advanced electric motor drives, and heat recovery systems.

Energy, Firm: Electric energy which is intended to have assured availability to the customer to meet all or any agreed upon portion of his load requirements.

Energy, Fuel Replacement: Electric energy generated at a hydroelectric plant as a substitute for energy which would otherwise have been generated by a thermal - electric plant.

Energy, Interchange: Electric energy received by one electric utility system usually in exchange for energy delivered to the other system at another time. Interchange energy is to be distinguished from a direct purchase or sale, although accumulated energy balances are sometimes settled for in cash.

Energy Loss: The difference between energy input and output as a result of transfer of energy between two points.

Energy, Maintenance: Energy delivered to other utilities during scheduled maintenance outages to their generation or transmission facilities.

Energy Management System (EMS): A computer-controlled system used by electric utility operators to monitor the real-time performance of the various elements of an electric system and to control generation and transmission facilities.

Energy, Off Peak: Electric energy supplied during periods of relatively low system demands as specified by the supplier.

Energy, On Peak: Electric energy supplied during periods of relatively high system demands as specified by the supplier. In the WSCC, on peak hours are defined as Monday through Saturday, HE 0700 to HE 1100, excluding designated holidays.

Energy Rate: See Energy Charge.

Energy Receipts: Energy generated by one electric utility system and received by another system through one or more transmission lines.

Energy, Renewable: Any energy resource which has recently originated in the sun, including direct and indirect solar radiation and intermediate solar energy forms such as wind, ocean thermal gradients, ocean currents and waves, hydropower, photovoltaic energy, products of photosynthetic processes, organic wastes, and others.

Energy Source: The primary source that provides the power that is converted to electricity through chemical, mechanical, or other means. Energy sources include coal, petroleum and petroleum products, gas, water, uranium, wind, sunlight, geothermal, and other sources.

Energy, Surplus: Energy generated that is beyond the immediate needs of the producing system. This energy is frequently obtained from spinning reserve and sold on an interruptible basis.

Energy Used By Producer: Energy generated and used by certain large industrial companies that own electric generating facilities whose output is not available to the public, but is included with the generation of electric utilities by the Federal Agency Regulatory Commission as part of the electric utility industry's generation.

Environmental Assessment: A concise written document prepared by a Federal agency that briefly provides sufficient evidence and analysis for determining whether to prepare an environmental impact statement or finding of no significant impact.

Environmental Impact Statement (EIS): A detailed written document prepared by a Federal agency on the environmental impacts of a proposed action that significantly affects the quality of the human environment. An environmental impact statement normally requires 2 to 2 ½ years to complete and is a tool for planning and decision- making and is a requirement of the National Environmental Policy Act.

Environmental Planning: A systematic process of analyzing need and environment and organizing their components into a plan which serves the need while minimizing adverse environmental effects.

EPA: Environmental Protection Agency

EPAct: Energy Policy Act of 1992

EPAMP: (Western’s) Energy Planning and Management Program

EPAMP-EIS: The EIS conducted for EPAMP

EPM-EIS: (Western’s Salt Lake City Area Integrated Projects) Electric Power Marketing EIS

EPRI: Electric Power Research Institute - an organization, financially supported by electric utilities, that conducts research into electric power issues.

Equity Capital: The sum of capital from retained earnings and the issuance of stocks.

Equivalent Barrel of Oil: A standard measure of heat content equivalent to the number of Btu in a representative barrel of oil, about 6,250,000 Btu.

EWG: Exempt Wholesale Generator

Excitation: The power required to energize the magnetic field of generators in an electric generating station, and transformers.

Exciter: A source, usually a direct-current generator, of current for initiating or developing a magnetic field in a generator.

Expenditure: The incurrence of a liability to obtain an asset or service.

Exports, Net Electric: Exports of electical energy in excess of imports across a political boundary or boundaries, being "Gross Out" less "Gross In" during a stated period. This term is applied also to power flow of load at stated times.

Extra High Voltage (EHV): Descriptive of transmission lines with voltage levels higher than high voltage (HV) but lower than Ultra High Voltage (UHV) levels. EHV is generally considered to range from the 345-kilovolt class or higher.

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Facility: An existing or planned location or site at which prime movers, electric generators, and/or equipment for converting mechanical, chemical, and/or nuclear energy into electric energy are situated, or will be situated. A facility may contain more than one generator of either the same or different prime mover type. For a cogenerator, the facility includes the industrial or commercial process.

Facilities Charge: An amount to be paid by the customer in a lump sum, or periodically as reimbursement for facilities furnishes. The charge may include operation and maintenance as well as fixed costs.

Fault: An unintentional short circuit in a power system, due to a breakdown in insulation and causing abnormal current flow. When the fault current flows in ground, the fault is called a Ground Fault (e.g., tree branch in the line or broken conductors that contact the ground or other conductors.

Fault Locator: A device or system that automatically indicates where a Fault occurred on a transmission line to expedite the dispatch of repair crews.

Federal Energy Regulatory Commission (FERC): A quasi-independent regulatory agency within the Department of Energy having jurisdiction over interstate electricity sales, wholesale electric rates, hydroelectric licensing, natural gas pricing, oil pipeline rates, and gas pipeline certification. A commission that has the authority to confirm, approve, and place in effect on a final basis, to remand, or disapprove power transmission rates developed by Western and other electric utilities. Formerly the Federal Power Commission (FPC).

Federal Power Act: Enacted in 1920 and amended in 1935, the Act consists of three parts. The first part incorporated the Federal Water Power Act administered by the former Federal Power Commission, whose activities were confined almost entirely to licensing non-Federal hydroelectric projects. Parts II and III were added with the passage of the Public Utility Act. These parts extended the Act's jurisdiction to include regulating the interstate transmission of electrical energy and rates for its sale as wholesale in interstate commerce. The Federal Energy Regulatory Commission is now charged with the administration of this law.

Federal Power Commission: The predecessor agency of the Federal Energy Regulatory Commission. The Federal Power Commission (FPC) was created by an Act of Congress under the Federal Water Power Act on June 10, 1920. It was charged originally with regulating the electric power and natural gas industries. The FPC was abolished on September 20, 1977, when the Department of Energy was created. The functions of the FPC were divided between the Department of Energy and the Federal Energy Regulatory Commission.

Feeder: A line from a generating plant or an interchange point between a transmission system and a load or distribution system.

FERC: See Federal Energy Regulatory Commission.

Firm Gas: Gas sold on a continuous and generally long-term contract.

Firm Obligation: A commitment to supply electric energy or to make capability available at any time specified during the period covered by the commitment.

Firm Power: Power or power producing capacity intended to be available at all times during the period covered by a guaranteed commitment to deliver, even under adverse conditions, except for reasons of certain uncontrollable forces or continuity of service provisions. (See Energy, Firm).

Firm Transmission Service: Point-to-point transmission service that is reserved and/or scheduled for a term of one year or more and that is of the same priority as that of the Transmission Provider's firm use of the transmission system. Firm Transmission service that is reserved and/or scheduled for a term of less than one year shall be considered Short-Term Firm Transmission Service for the purposes of service liability.

Firming Power: Power Western will purchase up to the SHP level. This type of purchase is included in the firm power rate.

Firming Purchases, WRP: Power purchased by Western or the Contractor above the AHP level up to the Contractor's CROD. This purchase is on a pass-through cost basis.

Fission: The splitting of a heavy nucleus into two parts (which are nuclei of lighter elements), accompanied by the release of a relatively large amount of energy and frequently one or more neutrons.

Flash over: A disruptive discharge through the air around or over the surface of an insulator. Can result from a lightning surge on a transmission line.

Flue Gas Desulfurization Unit (Scrubber): Equipment used to remove sulfur oxides from the combustion gases of a boiler plant before discharge to the atmosphere. Chemicals, such as lime, are used as the scrubbing media.

Flue Gas Particulate Collectors: Equipment used to remove fly ash from the combustion gases of a boiler plant before discharge to the atmosphere. Particulate collectors include electrostatic precipitators, mechanical collectors (cyclones), fabric filters (baghouses), and wet scrubbers.

Flux: The lines of force of a magnetic or electrostatic field.

Fly Ash: Particle matter from coal ash in which the particle diameter is less than one tenth of a millimeter. Fly ash is removed from the flue gas using flue gas particulate collectors such as fabric filters and electrostatic precipitators.

Forced Outage: The shutting down of a generating unit for emergency reasons. Generating units not in operation due to breakdowns, storms or other unplanned occurances.

Forebay: The impoundment immediately above a dam or hydroelectric plant intake structure.

Fossil Fuel: Any naturally occurring organic fuel, such as petroleum, coal, and natural gas.(See Conventional Fuels)

Fossil Fuel Powerplant: A powerplant that uses fossil fuel as a fuel source. A plant using coal, petroleum, or gas as its source of energy.

FPA: Federal Power Act

FR: Federal Register

Francis-type Unit (Francis Turbine): A hydraulic turbine using vanes to drive generating equipment. Water enters the unit at a right angle to the vanes and the turbine's center line.

FRC - Frequency Response Characteristic: For any change in generation/load balance in an interconnection, a frequency change occurs. FRC is how any system (control area) responds to this change during any imbalance resulting from a sudden loss of load or generation. System frequency does not return to its pre-disturbance level until the control area experiencing the imbalance corrects its imbalance.

FRN: Federal Register Notice

Frequency: The number of cycles through which an alternating current passes per second. Frequency has been generally standardized in the United States electric utility industry at 60 cycles per second (60 hertz).

Frequency Deviation: A change in system frequency from one moment to the next

Frequency Error: The difference between the actual and scheduled Interconnection frequency

Frequency Responsive Reserve (FRR): The portion of Operating Reserve that is expected to respond to Frequency Deviations within the Frequency Responsive Reserve Activation Period.

Frequency Responsive Reserve Activation Period:The period after a large frequency deviation in which Frequency Responsive Reserve (FRR) must be provided.

FRS: Frequency Response Standard.

FTE: Full-time equivalent. Represents one full-time employee.

FTR: Firm Transmission Rights

Fuel for Generation: Any substance that can be burned to produce heat; also, materials that can be fissioned in a chain reaction to produce heat. Includes all types of fuel (solid, liquid, gaseous, and nuclear) used exclusively for the production of electric energy. Fuel for other purposes, such as building heating or steam sales, is excluded.

Fuel Adjustment Clause: A clause in a rate schedule that provides for an adjustment of the customer's bill if the cost of fuel at the supplier's generating stations varies from a specified unit cost.

Fuel Elements (Nuclear): A rod, tube, plate, or other geometrical form into which nuclear fuel is fabricated for use in a reactor. Also referred to as a Fuel Assembly.

Fuel Cell: A system which converts the chemical energy of a fuel directly to direct current (DC) electricity without intermediate combustion or thermal cycles.

Fuel Expenses : These costs include the fuel used in the production of steam or driving another prime mover for the generation of electricity. Other associated expenses include unloading the shipped fuel and all handling of the fuel up to the point where it enters the first bunker, hopper, bucket, tank, or holder in the boiler house structure.
(Units most commonly used by electric utility companies)
Nuclear:
Cents per million Btu or mills per kilowatt hour: calculated on a fuel-cycle, which normally lasts 5 to 6 years, consists of all the steps associated with procurement, use and disposal of nuclear fuel; the cost (including interest charges) of each step must be accounted for in computing total fuel costs.
Oil:
Dollars per 42-gallon barrel (bbl) used for fuel oil , crude oil, and diesel oil, and small amounts of tar and gasoline.
Cents Per Million BTU Consumed:
Since coal is purchased on the basis of its heat content, its cost is measured in units of total cost of fuel consumed/total Btu content (in millions) of fuel consumed.
Coal:
Dollars per (short) ton: used for bituminous and anthracite coal and relatively small amounts of lignite and wood
Gas:
Cents per thousand cubic feet (Mcf) : used for natural, manufactured, mixed, and waste gas. Frequently expressed as cost per therm (100,000 Btu).

Fuel Replacement: (See Energy, Fuel Replacement).

Fuel Reprocessing (Nuclear): The processing of reactor fuel to recover the unused fissionable material.

Full-Forced Outage: The net capability of main generating units that are unavailable for load for emergency reasons.

Fuse: A protective device that consists of metal that melts under heat produced by an over-current condition, thereby breaking the circuit.

Fusion: The formation of a heavier nucleus from two lighter ones with the attendent release of energy.

FY: Fiscal year - Western's fiscal year runs from October 1 of a year through September 30 of the following year.

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GADS: Generating Availability Data System (a NERC database set)

Gas: A fuel burned under boilers and by internal combustion engines for electric generation. These include natural, manufactured, and waste gas.

Gas Turbine Plant: A plant in which the prime mover is a gas turbine. A gas turbine consists typically of an axial-flow air compressor, one or more combustion chambers, where liquid or gaseous fuel is burned and the hot gases are passed to the turbine and where the hot gases expand to drive the generator and are then used to run the compressor.
Combined Cycle: A gas turbine installation using waste heat boilers to capture exhaust energy for steam generation
Regenerative Cycle: a simple cycle gas turbine to which has been added a heat exchanger to warm the incoming combustion air with heat from the exhaust gasses to increase thermal efficiency.
Simple Cycle: Mechanically, the gas turbine is a very simple engine, consisting of a compressor section which pumps the air for combustion, and a combustion section where the compressed air is mixed with natural gas or oil and burned. The air, in turn, expands with the products of combustion and attains a higher temperature and pressure. This expanded mixture of air and gas then impinges on turbine blades attached to the same shaft as that of the compressor section, thus providing the power required to rotate the combustion air compressor. After the hot gasses pass through the compressor turbine, they go into the power turbine, where the shaft power is used to turn the generator or other powerplant equipment. (Sometimes referred to as a combustion turbine.)

GCD: Glen Canyon Dam (and power plant)

GCD-EIS: the Operation of Glen Canyon Dam EIS prepared by the Bureau of Reclamation

GCES: Glen Canyon Environmental Studies

GCMRC: Grand Canyon Monitoring and Research Center.

GCP Act (GCPA): Grand Canyon Protection Act of 1992

General Plant: A group of utility plant accounts not includible in the other functional utility plant accounts. Includes: Land and Land Rights, Structures and Improvements, Office Furniture and Equipment, Transportation Equipment, Stores Equipment, Tools, Shop and Garage Equipment, Laboratory Equipment, Power Operated Equipment, Communication Equipment, Miscellaneous Equipment, and Other Tangible Property.

Generating Station (Generating Plant or Power Plant): A station at which prime movers, electric generators, and auxiliary equipment are used for converting mechanical, chemical, and/or nuclear energy into electric energy.

Generating Unit: Any combination of physically connected generator(s), reactor(s), boiler(s), combustion turbine(s), or other prime mover(s) operated together to produce electric power.

Generation (Electricity): The process of producing electric energy by transforming other forms of energy; also, the amount of electric energy produced, expressed in watt-hours (Wh).

Generation, Gross: The total amount of electric energy produced by the generating units at a generating station or stations, measured at the generator terminals.

Generation, Net: Gross generation less the electric energy consumed at the generating station for station use.

Generation Reserve Margin: Reserve Capacity

Generator: In power systems, the machine which converts mechanical energy to electrical energy.

Geothermal: An electric generating station in which the prime mover is a steam turbine. The steam is generated in the earth by heat from the earth's magma.

Hydroelectric: An electric generating station in which the prime mover is a water wheel driven by falling water.

Nuclear: An electric generating station in which the prime mover is a steam turbine. The steam is generated in a reactor by heat from the fissioning of nuclear fuel.

Steam (Conventional): An electric generating station in which the prime mover is a steam turbine. The steam is generated in a boiler by heat from burning fossil fuels.

Generator, Induction: A nonsynchronous AC generator identical in construction with an AC motor, and which is driven above synchronous speed by external sources of mechanical power.

Generator Nameplate Capacity: The full-load continuous rating of a generator, prime mover, or other electric power production equipment under specific conditions as designated by the manufacturer. Installed generator nameplate rating is usually indicated on a nameplate physically attached to the generator.

Generator, Synchronous: A machine that generates an alternating current when its armature field is rotated within the armature winding. The output frequency is exactly proportional to the speed at which the generator is driven.

Geothermal Plant: A plant in which the prime mover is a steam turbine. The turbine is driven either by steam produced from hot water or by natural steam that derives its energy from heat found in rocks or fluids at various depths beneath the surface of the earth. The energy is extracted by drilling and/or pumping. The cost of producing electicity with geothermal resources depends on the resource temperature, plant size, plant efficiency, production well depth, and production well flow rate.

Gigawatt (GW): One billion watts.

Gigawatthour (GWh): One billion watthours.

Glen Canyon Dam: The dam on the Colorado River which forms Lake Powell. One of several dams and powerplants that make up the CRSP.

Good Utility Practice: Any of the practices, methods, and acts engaged in or approved by a significant portion of the electric utility industry during the relevant time period, or any of the practices, methods, and acts which, in the exercise of reasonable judgment in light of the facts known at the time the decision was made, could have been expected to accomplish the desired result of the lowest reasonable cost consistent with good business practices, reliability, safety and expedition. Good Utility Practice is not intended to be limited to the optimum practice, method, or act to the exclusion of all others, but rather to be acceptable practices, methods, or acts generally accepted in the region and consistently adhered to by the Transmission Provider.

Governor: The device which gauges the speed of a Turbine and activates measures to control the speed.

GPM: gallons per minute

Greenhouse Effect: The increasing mean global surface temperature of the earth caused by gases in the atmosphere (including carbon dioxide, methane, nitrous oxide, ozone, and chlorofluorocarbon). The greenhouse effect allows solar radiation to penetrate but absorbs the infrared radiation returning to space.

Grid: The name given to an interconnected system of electric transmission lines and associated equipment for the movement or transfer of electric energy in bulk between points of supply and points of demand. The layout of an electrical distribution system.

Gross Generation: The total amount of electric energy produced by the generating units in a generating station or stations.

Gross, Net: Generation less kilowatt hours consumed out of gross generation for station use.

Ground: A conducting connection between an electric circuit and earth.

Grounded System: A system of conductors in which at least one conductor (usually in the middle wire or neutral point of transformer or generator windings) is intentionally grounded either solidly or through a current-limiting device.

Grounding Switch: A switch by means of which a circuit may be connected to ground.

Guy: A steel wire used to support or strengthen a structure.

GW: See Gigawatt; 1,000 Megawatts (MW); 1,000,000,000 watts.

GWh: See Gigawatthour.

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Hand Line: Non-metallic rope and small pully for raising and lowering tools and equipment to line workers.

Hazardous Material: A substance or material which has been determined by the Secretary of Transportation to be capable of posing an unreasonable risk to health, safety, and property when transported in commerce and which has been so designated.

Hazardous Voltage: Above 600 volts.

HE: Hour ending. For example, HE 0700 means the hour beginning at 6 a.m. and ending at 7 a.m.

Head: The dam creates a "head" (height from the power plant turbine to the water surface behind the dam). The amount of head, coupled with the volume of water flowing through the turbines, determines how much energy a hydro powerplant produces. When head and flow are increased, power output increases. The combination of "head" and "flow" produces energy.

Head, Critical: The head at which full-gate output of the turbine equals the nameplate generator capacity.

Head Differential: Head differential is the force per unit area exerted by a column of liquid at a certain height compared to some lower point. The higher the head; the better able it is to produce hydroelectric generation.

Head, Gross: The difference in elevations between water surfaces of the forebay and tailrace under specific conditions. Gross head usually refers to the difference between normal full pool and average tailwater.

Head, Net (Effective Head): Gross head less all hydraulic losses except those attributable to the turbine.

Heat Exchanger: A device that transfers heat from one material, such as gas or water, to another substance with no direct contact between the two materials.

Heat Pump: A year-round air conditioning system employing refrigeration equipment in a manner which enables usable heat to be supplied to a space during the winter period and by reversing the operation cycle to extract heat from the same space during the summer period. When operating as a heating system, heat is absorbed from an outside medium (either air, water, or the earth) and this heat together with the heat equivalent of the work of compression is supplied to the space to be heated. When operating on the cooling cycle, heat is absorbed from the space to be cooled, and this heat together with the heat equivalent of the work of compression is rejected to the outside medium.

Heat Rate: A measure of the thermal efficiency of a generating station. Generally expressed in Btu per net kilowatt-hour. It is computed by dividing the total Btu content of fuel burned for electric generation by the resulting net kilowatt-hour generation.

Heating System: Energy Efficiency program promotion aimed at improving the efficiency of the heating delivery system, including replacement, in the residential, commercial, or industrial sectors.

Heavy Oil: The fuel oils remaining after the lighter oils have been distilled off during the refining process. Except for start-up and flame stabilization, virtually all petroleum used in steam plants is heavy oil.

Hertz (Hz): Frequency in Cycles per second.

H-Frame: A wooden pole structure commonly used for voltages from 69 thru 230 kV, designation originates from appearance of the structure which has a double-plank cross arm.

High Side: The higher voltage electrical system of two systems connected by a transformer.

Hockey Stick Bid: A bid in a market-clearing price electicity auction that offers most capacity at the marginal cost and the remainder at much higher costs. This is a bidding strategy meant to increase the market-clearing price paid for all capacity.

Horsepower (hp): A standard unit of power equal to 746 watts.

Hot Line Order: A statement with documentation from an operations supervisor to a job supervisor that the automatic reclosing is turned off and that equipment covered by a hot line order will not be re-energized until the conditions stated on the hot line order are met. This allows specific work to be done on or near a line or other equipment without requiring that it be disconnected from all source of electrical energy. The equipment is considered to be energized or “hot.”

Hot Stick: An insulated stick used for repair work on live lines, and for installing protective grounding.

Hour-Ahead Market: The electric power futures market that is established 1-hour before delivery to End-Use Customers.

Hourly Non-Firm Transmission Service: Point-to-point transmission that is scheduled and paid for on an as-available basis and is subject to interruption.

Hydraulic Turbines: Turbines activated by the flow of water under pressure; the prime mover or driving force of an electric generator.

Hydro: A term used to identify a type of generating station, power, or energy output in which the prime mover is driven by water power. A hydroelectric plant, for example, is an electric power plant in which the energy of falling water is converted into electricity by turning a turbine generator.

Hydroelectric Plant: A plant in which the turbine generators are driven by falling water.

Hysteresis: Loss in the core of a transformer due to molecular friction.

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IBWC: International Boundary and Water Commission (Operators of the Falcon and Amistad hydroelectric plants on the Rio Grande River in Texas.)

Impedance: A characteristic of an electric Circuit which determines its hindrance to the flow of electricity. More specifically, at a given applied Voltage (E) impedance (Z) determines the resulting Current (I), or E=IZ, which means the higher the impedance, the lower the current. Impedance is mathematically equivalent to the square root of the sum of the Resistance squared and the Reactance squared.

Imports, Net Electric: Imports of electric energy in excess of exports across a political boundary or boundaries, being "Gross In" less "Gross Out" during a stated period. This term applies also to power flow or load at stated times.

Increasing Block Rate: A rate design for a customer class for which the unit charge for electricity increases as usage increases.

Incremental Cost (Energy): The increase in cost of generating or transmitting additional energy above some previously determined base amount.

Incremental Effects: The annual effects in energy use (measured in megawatthours) and peak load (measured in kilowatts) caused by new participants in existing DSM programs and all participants in new DSM programs during a given year. Reported Incremental Effects should be annualized to indicate the program effects that would have occurred had these participants been initiated into the program on January 1 of the given year. Incremental effects are not simply the Annual Effects of a given year minus the Annual Effects of the prior year, since these net effects would fail to account for program attrition, degradation, demolition, and participant dropouts.

Independent Power Producers (IPP): A non-utility.

Indirect Utility Cost: A utility cost that may not be meaningfully identified with any particular DSM program category. Indirect costs could be attributable to one of several accounting cost categories (i.e., Administrative, Marketing, Monitoring & Evaluation, Utility-Earned Incentives, Other). Accounting costs that are known DSM program costs should not be reported under Indirect Utility Cost, rather those costs should be reported as Direct Utility Costs under the appropriate DSM program category.

Inductance: The property of an electric circuit by virtue of which a varying current induces a voltage in that circuit or a neighboring circuit.

Industrial: The industrial sector is generally defined as manufacturing, construction, mining, agriculture, fishing, and forestry establishments (Standard Industrial Classification [SIC] codes 01-39). The utility may classify industrial service using the SIC codes, or based on demand or annual usage exceeding some specified limit. The limit may be set by the utility based on the rate schedule of the utility.

Insulator: An extremely low conductive support for a conductor. It inhibits the flow of current from the conductor to earth or another conductor.

Insulator, Suspension: An insulator made of an extremely low conducting material such as porcelain or glass used to suspend the conductor from the tower or structure. Main parts consist of the cap (upper part made of metal) ; the skirt (middle section made of insulating material); and the ball stem (lower metal portion.) The ball stem connects to the cap of next insulator in a string.

Integrated Demand: The demand usually determined by an integrating demand meter or by the integration of a load curve. It is the summation of the continuously varying instantaneous demands during a specified demand interval.

Integrated Projects: See SLCA/IP.

Integrated Resource Planning: Consideration of both supply-side resources and demand-side management programs as potential sources of power to fulfill future demand and energy requirements.

Interchange Energy: Kilowatt-hours delivered to or received by one electric utility system from another. They may be returned in kind at a later time or may be accumulated as energy balances until the end of a stated period. Settlement may be by payment or on a pooling basis.

Interconnection: A tie permitting a flow of energy between the facilities of two electric systems. Also called Intertie.

Interconnected System: A system consisting of two or more individual power systems normally operating with connecting Tie Lines.

Interdepartmental Service (Electric):Interdepartmental service includes amounts charged by the electric department at tariff or other specified rates for electricity supplied by it to other utility departments.

Interior: U.S. Department of Interior.

Interlock: An arrangement that keeps one operation or sequence of operations from taking place until another condition has been satisfied.

Intermediate Load (Electric System): The range from base load to a point between base load and peak. This point may be the midpoint, a percent of the peakload, or the load over a specified time period.

Internal Combustion Plant: A plant in which the prime mover is an internal combustion engine. An internal combustion engine has one or more cylinders in which the process of combustion takes place, converting energy released from the rapid burning of a fuel-air mixture into mechanical energy. Diesel or gas-fired engines are the principal types used in electric plants. The plant is usually operated during periods of high demand for electricity.

Internal Fault: A fault within the protective zone of a relay.

Interruptible Gas: Gas sold to customers with a provision that permits curtailment or cessation of service at the discretion of the distributing company under certain circumstances, as specified in the service contract.

Interruptible Load: Refers to program activities that, in accordance with contractual arrangements, can interrupt consumer load at times of seasonal peak load by direct control of the utility system operator or by action of the consumer at the direct request of the system operator. It usually involves commercial and industrial consumers. In some instances the load reduction may be affected by direct action of the system operator (remote tripping) after notice to the consumer in accordance with contractual provisions. For example, loads that can be interrupted to fulfill planning or operation reserve requirements should be reported as Interruptible Load. Interruptible Load as defined here excludes Direct Load Control and Other Load Management. (Interruptible Load, as reported here, is synonymous with Interruptible Demand reported to the North American Electric Reliability Council on the voluntary Office of Energy Emergency Operations Form OE-411, "Coordinated Regional Bulk Power Supply Program Report," with the exception that annual peak load effects are reported on the Form EIA-861 and seasonal (i.e., summer and winter) peak load effects are reported on the OE-411).

Interruption: The loss of service to one or more consumers. An interruption is the result of one or more component outages.

Intertie: A transmission line or system of transmission lines permitting a flow of energy between major power systems.

Inverted Rate Design: A rate design for a customer class for which the unit charge for electricity increases as usage increases.

Inverter: An electro-mechanical or electronic device for converting direct current into alternating current.

Investment or Power Investment: (from RA6120.2) "Investment" or "power investment" means unless otherwise indicated in the context, investment allocated to be repaid from power revenues.

Investor-Owned Electric Utilities (IOU): Those electric utilities organized as tax- paying businesses usually financed by the sale of securities in the free market, and whose properties are managed by representatives regularly elected by their shareholders. Investor owned electric utilities which may be owned by an individual proprietor or a small group of people, are usually corporations owned by the general public.

Ion: An atom that has too many or too few electrons, causing it to be chemically active; an electron that is not associated (in orbit) with a nucleus.

Ionizing Radiation: Any radiation capable of displacing electrons from atoms and molecules, thereby producing ions. Examples: alpha, beta, gamma, x-rays, neutrons and ultraviolet light. High doses of ionizing radiation may produce severe skin and tissue damage.

IOS - Interconnected Operating Services: IOS are the elemental 'reliability building blocks' from generation (and sometimes load) necessary to maintain bulk electric system reliability, (sometimes referred to as ancillary services, such as regulation, load following, contingency reserves, Frequency Response, reactive power supply, and black-start capability).

IOU: See Investor-Owned Utility

IPP: Independent Power Producer, or Independent Power Project

IRP: See Integrated Resource Planning

ISO: Independent System Operator

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Joule: Unit of energy (1 watt-second) under the international system. As a thermal unit, 1 joule equals 0.239 calories.

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Kaplan Unit (Kaplan Turbine): A hydraulic turbine using propeller-shaped blades, which are adjustable under load, to drive generating equipment.

Kilovar (kVAR): 1,000 reactive volt-ampere.

Kilovolt (kV): 1,000 volts (see VOLT).

Kilovolt-Ampere (kVA): 1,000 Volt-amperes (defined herein).

Kilowatt (kW): 1,000 watts (see Watt).

Kilowatthour (kWh): The common unit of electric energy equal to one kilowatt of power supplied to or taken from an electric circuit for one hour. One kWh is equivalent to 3,413 btu.

kW-month: Unit of electric energy, equal to one kW taken for a period of one month.

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Lattice Tower: A transmission tower constructed of strips of steel.

Lead Time: The time required to place a large facility in service.

Leverage Ratio: A measure that indicates the financial ability to meet debt service requirements and increase the value of the investment to the stockholders (i.e., the ratio of total debt to total assets).

Liability: An amount payable in dollars or by future services to be rendered.

Light Oil: Lighter fuel oils distilled off during the refining process. Virtually all petroleum used in internal combustion and gas turbine engines is light oil.

Lightning Arrestor: (See Surge Arrestor)

Lignite: A brownish-black coal of low rank with high inherent moisture and volatile matter (used almost exclusively for electric power generation). It is also referred to as brown coal. Comprises two groups classified according to the following ASTM Specification D388-84 for calorific values on a moist material-matter-free basis.

Line Compensation: The balancing of line impedance, utilizing series capacitors.

Line Impedance: The apparent opposition to the flow of alternating current that is analogous to the actual electrical resistance of a direct current circuit.

Linejack: A protective device that disconnects the tap from the main line feeder when excessive current flows through the tap. It protects the main line feeder from damage and prevents extensive and excessive customer outages.

Line Loss: Energy loss on a transmission or distribution line caused by resistance in the conductor and resulting in heating of the conductor.

Lineman: A payroll classification or title given a craftsperson whose duties include climbing wood poles or steel structures to perform work on electric power transmission and distribution circuits.

Line Trap: (See Wave Trap).

Live Line Maintenance: Work performed on transmission lines under full line voltage when it is not practical to take the line out of service. This work can be done only in certain fair weather conditions with special tools and specific procedures.

LMP: Locational Marginal Pricing

Load (Electric): The amount of electric power delivered or required at any specific point or points on a system. The requirement originates at the energy consuming equipment of the consumers. An end-use device or an end-use customer that receives power from the electric system. Load should not be confused with Demand, which is the measure of power that a Load receives or requires.

Load Building: Refers to programs that are aimed at increasing the usage of existing electric equipment or the addition of electric equipment. Examples include industrial technologies such as induction heating and melting, direct arc furnaces and infrared drying; cooking for commercial establishments; and heat pumps for residences. Load Building includes programs that promote electric fuel substitution. Load Building effects should be reported as a negative number, shown with a minus sign.

Load Center: A point at which the load of a given area is assumed to be concentrated.

Load Controller: An electrical, mechanical, or electromechanical device or system operated by an electrical utility, which is designed to switch electric loads on and off to achieve a utility system peak power reduction and optimization of system energy use.

Load Curve: A curve on a chart showing power (kilowatts) supplied, plotted against time of occurrence, and illustrating the varying magnitude of the load during the period covered.

Load Diversity: The difference between the sum of the maximum of two or more individual loads and the coincident or combined maximum load, usually measured in kilowatts.

Load Factor: The ratio of the average load in kilowatts supplied during a designated period to the peak or maximum load in kilowatts occurring in that period. Load factor, in percent, also may be derived by multiplying the kilowatt-hours in the period by 100 and dividing by the product of the maximum demand in kilowatts and the number of hours in the period.

Load Flow Model: A computer-based model to analyze the flow of electric power from generating sources to loads through transmission lines at a certain point in time.

Load Frequency Control: The regulation of the power output of electric generators within a prescribed area in response to changes in system frequency, tie-line loading, or the relation of these to each other, so as to maintain the scheduled system frequency and/or the established interchange with other areas within predetermined limits. This term has generally been replaced with the term "Automatic Generation Control (AGC)".

Load Growth: The growth in energy and power demands by a utility's customers.

Load Interrupter Switch: A power system switch designed to interrupt a circuit under load or a limited amount of fault current. Provides economical switching for CAPACITORS and REACTORS and limited FAULT interruption. The interrupting capacity of the switch is usually significantly less than that of a POWER CIRCUIT BREAKER. Load interrupters may be applied at any voltage. On the WAPA system this device may, like a power circuit breaker, use oil, vacuum, or SF6 for arc quenching.

Load Management: Influencing the level and shape of the demand for electrical energy so that demand conforms to individual present supply situations and long-run objectives and constraints.

Load Pattern: The variation with time of the energy use in an electric circuit. In most situations, such as an individual home, electrical energy use varies as lights are turned on or off or as household appliances are used or charged.

Load Ratio Share: Ratio of a Transmission Customer's Network Load to the Transmission Provider's total load; calculated on a rolling twelve month basis.

Load Shedding: A method whereby loads in isolated areas are dropped by automatic relays to provide protection for the bulk power system. This could occur when generation is insufficient to meed load or transmission lines are in danger of overload.

Local Publicly Owned Electric Utilities: A municipal corporation, a municipal utility district, an irrigation district, or a joint power authority (which can include one or more of the agencies mention above) furnishing electric services over its own transmission facilities, or furnishing electric service over its own or its members' distribution system.

Locational Market Clearing Price: The price at which supply equals demand at a specified location. All demand which is prepared to pay at least this price at the specified location has been satisfied. All supply which is prepared to operate at or below this price in the specified location has been purchased.

Lockout: To prevent the reclosure of a power circuit breaker.

Lockout Relay: An electrically reset or hand reset auxiliary relay whose function is to hold associated devices inoperative until reset.

Long-Term WRP: Long-Term Western Replacement Power is power purchased by Western for a period of one year or longer, and is considered part of the customer/contractor’s CROD.

Loop Flow: The unscheduled power that flows inadvertently across a power system that is caused by power taking the path of least resistance from generation to load instead of flowing across a particular schedule or contract transmission path.

Loss: The power dissipated in a power system circuit or portion of a circuit expressed in watts. In communications, the ratio of the signal power delivered by a device under ideal or reference conditions to the signal power actually delivered, expressed in db.

Loss Factor: The ratio of the average power loss to the peak load power loss, during a specified period of time.

Loss of Load Probability (LOLP): A measure of the expectation that the system demand will exceed capacity during a given period, often expressed as the expected numbers of days per year.

Low-Profile: Describes a type of substation design which uses low elevations in the arrangement of electrical components and building construction.

LSE: Load Serving Entity.

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Magnetohydrodynamic (MHD) Generator: An expansion engine in which hot, partially ionized gases are forced through a magnetic field. Movement of the electrically conducting gas through the field generates an electric current that is collected by electrodes lining the expansion chamber.

Main and Transfer Bus Scheme: This scheme uses two buses with a single breaker for each line position. There generally is an extra breaker (bus tie) between the buses for use in any line position when it is necessary to work on the line breaker. In this scheme, only the main bus normally carries current--the transfer bus carries current only when a line breaker has been bypassed over the bus tie breaker.

Margin: The difference between net system generating capability and system maximum load requirements, including net schedule transfers with other systems.

Marginal Cost Pricing: Pricing at the cost of producing the next unit of the good.

Marginal Price: The payment required to obtain one additional unit of a good.

Market Clearing Price (MCP): The price at a location at which supply equals demand - all demand at or above this price has been satisfied, and all supply at or below this price has been purchased. Sometimes referred to as the Strike Price or the Clearing Price.

Market Forces: Competition for sales, new alliances, innovative pricing structures, customer demand, choice, and various kinds of services.

Market Participant: An entity who participates in the electrical energy marketplace through the buying and selling of electrical energy or services

Marketable Resource: Firm capacity and energy available for marketing after many factors are considered.

Marketer: An entity who takes title to electric power and then resells the power to end-use customers. This entity, who acts for itself in negotiating contracts, purchases, or sales of electrical energy, is required to meet two FERC tests to be certified as a Power Marketer: 1) show lack or adequate mitigation of transmission power; and 2) prove non-dominance of market power.

Marketing Cost: Expenses directly associated with the preparation and implementation of the strategies designed to encourage participation in a DSM program. The category excludes general market and load research costs.

Maximum Demand: The greatest of all demands of the load that has occurred within a specified period of time.

Mcf: One thousand cubic feet.

MCP: see Market Clearing Price

Median Stream Flow (Median Hydro): The rate of discharge of a stream for which there are equal numbers of greater and lesser flow occurrences during a specified period.

Mega: A prefix indicating a million; thus; a megavolt (Mv) equals 1,000,000 Volts and a megawatt (MW) equals 1,000,000 Watts.

Megawatt (MW): One million watts.

Megawatthour (MWh): One million watt-hours.

Merchant Function: A power marketing function within the CRSP MC that balances loads and resources for the CRSP MC, other regions within Western, and customers and purchases and sells energy on the open market.

Member System: An Eligible Customer operating as a part of a lawful combination, partnership, association, or joint action agency composed exclusively of Eligible Customers.

Merit Order Rank: The ranking by a power system operator of generation according to their applicable bid prices for scheduling and price setting purposes.

Metric Ton: A unit of weight equal to 1.102 short tons.

MGD: million gallons per day

Microwaves: In general usage, microwaves refer to those radio frequencies whose wavelengths are sufficiently short to exhibit some of the properties of light. Microwaves are usually used in point-to-point communications because they are easily concentrated into a beam. Frequencies of 1,000 megahertz and up are usually considered to be microwave frequencies.

Mid-Continent Area Power Pool (MAPP): One of nine Regional Reliability Councils of the North American Electric Reliability Council (NERC) that covers all of the states of Iowa, Minnesota, Nebraska, and North Dakota; portions of the state of Illinois, Michigan, Montana, South Dakota, and Wisconsin; and the provinces of Manitoba and Saskatchewan.

Mill: Unit of monetary value equal to one thousandth of a U.S. dollar; i.e., 1/10th of a cent. Used to express wholesale energy and composite electric rates.

Mills/kWh: Mills per kilowatt-hour.

Mine-Mouth Plant: A steam electric powerplant built close to coal mines and associated with delivery of output via transmission lines over long distances as contrasted with plants located near load centers and at some distance from sources of fuel supply.

Minimum Ground Clearance: The least distance that a conductor is allowed to approach the ground level under the selected design loading conditions.

Minimum Operating Reliability Criteria (MORC): Minimum operating reserve is the sum of a)regulating reserve plus b)contingency reserve plus C) additional reserve for interruptible imports plus D) additional reserve for on-demand obligations.

MMBtu: One million British Thermal Units. (Note: Use of the term MM to designate one million is considered obsolete.)

MMcf: One million cubic feet. A measure of natural gas.

Monitoring & Evaluation Cost: Expenditures associated with the planning, collection, and analysis of data used to assess program operation and effects. It includes activities such as load metering, customer surveys, new technology testing, and program evaluations that are intended to establish or improve the ability to monitor and evaluate the impacts of DSM programs, collectively or individually.

Most Severe Single Contingency (MSSC): A Control Area's single credible event that would cause the greatest change in the Control Area's ACE.

MOU: Memorandum of Understanding

Multi(ple)-Purpose Reservoir (or Project): A reservoir (or project) planned to be used for more than one purpose (e.g., flood control, irrigation, recreation, power generation, wildlife)

Multirate Watthour Meter: A watt hour meter having more than one set of energy recording registers, e.g., a dual rate or differential register meter.

Municipally-Owned Electric System: An electric utility system owned and/or operated by a municipality engaged in serving residential, commercial, and/or industrial customers, usually - but not always - within the boundaries of the municipality. A Local Publicly Owned Electric Utility that owns or operates electric facilities subject to the jurisdiction of a municipality, as opposed to being subject to FERC jurisdiction

Must Take Resources: Generation resources including QF generating units, nuclear units, and pre-existing power purchase contracts with minimum energy-take requirements that are dispatched before other generation.

MW: See Megawatt; 1,000kW; 1,000,000 watts.

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N-1 Outage (or Contingency)- A transmission system condition where one system element (transmission line, transformer, generator, etc.) experiences an outage.

N-2 Outage (or Contingency)- A transmission system condition where two system elements (transmission lines, transformers, generators, etc.) experience an outage.

Name Plate Rating: The full-load continuous rating of a generator, prime mover or other electrical equipment under specified conditions as designated by the manufacturer. It is usually indicated on a name plate attached to the individual machine or device. The name plate rating of a steam electric turbine- generator set is the guaranteed continuous output in kilowatts or kVA and power factor at generator terminals when the turbine is clean and operating under specified throttle steam pressure and temperature, specified reheat temperature, specified exhaust pressure, and with full extraction from all extraction openings.

National Association of Regulatory Utility Commissioners (NARUC): An advisory council composed of Federal and state regulatory commissioners having jurisdiction over transportation agencies and public utilities.

Native Load Customers: The wholesale and retail customers on whose behalf the Transmission Provider, by statute, franchise, regulatory requirements, or contract, has undertaken an obligation to construct and operate the Transmission Provider's system to meet the reliable electric needs of such customers.

Natural Gas: A naturally occurring mixture of hydrocarbon and nonhydrocarbon gases found in porous geological formations beneath the earth's surface, often in association with petroleum. The principal constituent is methane.

NEPA: National Environmental Policy Act of 1969 (42 U.S.C. 4321, et Seq).

NERC: See North American Electric Reliability Council

Net Capability: The maximum load carrying ability of the equipment, exclusive of station use, under specified conditions for a given time interval, independent of the characteristics of the load. (Capability is determined by design characteristics, physical conditions, adequacy of prime mover, energy supply, and operating limitations as cooling and circulating water supply and temperature, headwater and tailwater elevations, and electrical use.)

Net For Distribution: On an electric system, this means the kilowatt-hours available for total system load. Specifically, it is the sum of net generation by the system's own plants, purchased energy, and net interchange (in less out).

Net Generation: Gross generation minus plant use from all electric utility owned plants. The energy required for pumping at a pumped storage plant is regarded as plant use and must be deducted from the gross generation.

Net Summer Capability: The steady hourly output, which generating equipment is expected to supply to system load exclusive of auxiliary power, as demonstrated by tests at the time of summer peak load.

Net Winter Capability: The steady hourly output which generating equipment is expected to supply to system load exclusive of auxiliary power, as demonstrated by tests at the time of winter peak load.

Network: A system of transmission or distribution lines so cross-connected and operated as to permit multiple supply to any principal point on it.

Network Customers: Entities receiving transmission service pursuant to the terms of the Transmission Provider's Network Integration Tariff.

Network Integration Transmission Service: Network Integration Transmission Service allows a Transmission Customer to integrate, plan, economically dispatch, and regulate its Network Resources to serve its Network Load in a manner comparable to that in which the Transmission Provider utilizes its Transmission System to serve its Native Load customers. Network Integration Transmission Service also may be used by the Transmission Customer to deliver non-firm energy purchases to its Network Load without additional charge.

Network Load: The designated load of a Transmission Customer, including the entire load of all Member Systems designated pursuant to Section 6.0. A Transmission Customer's Network Load shall not be reduced to reflect any portion of such load served by the output of any generating facilities owned, or generation purchased, by the Transmission Customer or its Member Systems.

Neutral Relay: A protective relay that responds to quantities in the neutral of a power circuit.

New Construction: Energy efficiency program promotion to encourage the building of new homes, buildings, and plants to exceed standard government-mandated energy efficiency codes; it may include major renovations of existing facilities.

Noncoincidental Peak Load: The sum of two or more peak loads on individual systems that do not occur in the same time interval. Meaningful only when considering loads within a limited period of time, such as a day, week, month, a heating or cooling season, and usually for not more than one year.

Nonfirm Energy (or Power): Energy supplied or available under an arrangement which does not have the guaranteed continuous availability feature of Firm Power.

Non-Firm Transmission Service: Point-to-point transmission service that is reserved and/or scheduled on an as-available basis and is subject to interruption. Non-firm Transmission Service is available on a stand-alone basis as either Hourly Non-firm Transmission Service or Short-Term Non-firm Transmission Service.

Non-Spinning Reserve: The portion of off-line generating capacity which is capable of being loaded in 10 minutes, or load which is capable of being interrupted in 10 minutes and which is capable of running (or being interrupted) for at least two hours.

Nonutility Power Producer: A corporation, person, agency, authority, or other legal entity or instrumentality that owns electric generating capacity and is not an electric utility. Nonutility power producers include qualifying cogenerators, qualifying small power producers, and other nonutility generators (including independent power producers) without a designated franchised service area, and which do not file forms listed in the Code of Federal Regulations, Title 18, Part 141. See NUG.

NOPR: Notice of Proposed Rulemaking (by FERC)

North American Electric Reliability Council (NERC): A council formed in 1968 by the electric utility industry to promote the reliability and adequacy of bulk power supply in the electric utility systems of North America. NERC consists of ten regional reliability councils and encompasses essentially all the power regions of the contiguous United States, Canada, and Mexico. The NERC Regions are:

ASCC - Alaskan System Coordination Council

ECAR - East Central Area Reliability Coordination Agreement

ERCOT - Electric Reliability Council of Texas

MAIN - Mid-America Interconnected Network

MAAC - Mid-Atlantic Area Council

MAPP - Mid-Continent Area Power Pool

NPCC - Northeast Power Coordinating Council

SERC - Southeastern Electric Reliability Council

SPP - Southwest Power Pool

WECC - Western Electric Coordinating Council

Notice of Intent: A public notice that an environmental impact statement will be prepared and considered in the decision making for a proposed action.

NREL: National Renewable Energy Laboratory

Nuclear Fuel: Fissionable materials that have been enriched to such a composition that, when placed in a nuclear reactor, will support a self-sustaining fission chain reaction, producing heat in a controlled manner for process use.

Nuclear Power Plant: A facility in which heat produced in a reactor by the fissioning of nuclear fuel is used to drive a steam turbine.

NUG: Non-Utility Generation - Generation by producers having generating plants for the purpose of supplying electric power required in the conduct of their industrial and commercial operations. Generation by mining, manufacturing, and commercial establishments and by stationary plants of railroads and railways for active power is included.

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OASIS: Open Access Same-Time Information System. An OASIS is a webstie that provides access to information on transmission pricing and availability for potential transmission customers.

OAT: Open Access Tariff

Obligation to Serve: A regulatory obligation of a utility to provide electric planning services for all customers and to assure adequate supply of electricity now and in the future.

Off-Peak Energy: Energy supplied during periods of relatively low system demand for electrical energy as specified by the supplier.

Off-Peak Gas: Gas that is to be delivered and taken on demand when demand is not at its peak.

Ogee: A double curve with the shape of an elongated "S". A shape used in water conveyence structures.

Ohm: The unit of measurement of electrical resistance. The resistance of a circuit in which a potential difference of 1 volt produces a current of 1 ampere.

Oil Burned for Fuel: A term comprising fuel oil, crude oil, diesel oil and small amounts of tar and gasoline, with fuel oil predominating. See Fuel for Electric Generation.

Oil, Heavy: Fuel oils remaining after the ligher oils have been distilled off during the refining process. Included are products known as American Society for Testing and Materials (ASTM) grades 4,5, and 6 and residual oils. Except for startup and flame stabilization, virtually all oil used in steam plants is heavy oil.

Oil, Light: Lighter oils distilled off during the refining process. Included are products known as American Society for Testing and Materials (ASTM) grade 2 heating oil, kerosene, and jet fuel. Virtually all oil used in internal combustion and gas turbine engines is light oil.

OMB: Office of Management and Budget.

O&M: Operation and maintenance.

OM&R:Operation, maintenance and replacement.

One-Line Diagram: A diagram that shows, by means of single lines and graphic symbols for components, the course of a system of electric circuits to and from those components. WAPA makes extensive use of one-line diagrams of substations for analysis and design. Dynamic one-line diagrams of all WAPA substations presenting continually updated information on the status of buses and components are displayed on System Control Center consoles for monitoring and controlling the WAPA transmission network.

On-Peak Energy: Energy supplied during periods of relatively high system demands as specified by the supplier.

On-Peak Demand Register: A register within an electric meter that will record the total energy used and in addition will register maximum demand during on-peak periods. The control of the demand recording is with a solenoid-operated demand gear train that may be actuated from a local device or from a device located at a remote location.

Open: When referring to a circuit breaker or other switching device, open means the switch contacts are apart, the switch is "off", and current cannot flow (in contrast to Closed).

Operable Nuclear Unit: A nuclear unit is "operable" after it completes low power testing and is granted authorization to operate at full power. This occurs when it receives its full power amendment to its operating license from the Nuclear Regulatory Commission.

Operating Factor (Operation Factor): The average operating level of a resource, when in use. (e.g., a resource with a 50% capacity factor, could operate half of the time at an operating factor of 100%, or all of the time at an operating factor of 50%)

Operating Reserve: That capability above firm system demand required to provide for regulation, load forecasting error, equipment forced and scheduled outages, and local area protection. The combination of spinning and non-spinning reserve required to meet WSCC and NERC requirements for reliable grid operation.

Operating Reserve - Spinning: The provision of Resource Capacity in excess of current and anticipated demand that is synchronized to the system and deployable.

Operating Reserve - Supplemental: The provision of Resource Capacity in excess of current and anticipated demand and Operating Reserve - Spinning that is: (1) synchronized, or is capable of being synchronized to the system, or, (2) load that can be removed from the system, or (3) interchange that can be recalled.

Optimal Power Flow (OPF): An estimation procedure utilizing a computer software package capable of minimizing a desired objective function within system operating limits by scheduling designated active and/or reactive resources, and by recognizing the interactions between generation load, and the transmission grid.

OTC, Operating Transfer Capability: - Represents the path maximum actual flow capability.

Other DSM Programs: A residual category to capture the effects of DSM programs that cannot be meaningfully included in any other DSM program category. The energy effects attributable to this category should be the net effects of all the residual programs. Programs that promote consumer's substitution of electricity by other energy types should be included in Other DSM Programs. Also, self-generation should be included in Other DSM Programs to the extent that it is not accounted for as backup generation in Other Load Management or Interruptible Load categories.

Other Incentives: Energy Efficiency programs that offer cash or noncash awards to electric energy efficiency deliverers, such as appliance and equipment dealers, building contractors, and architectural and engineering firms, that encourage consumer participation in a DSM program and adoption of recommended measures.

Other Load Management: Refers to programs other than Direct Load Control and Interruptible Load that limit or shift peak load from on-peak to off-peak time periods. It includes technologies that primarily shift all or part of a load from one time-of-day to another and secondarily may have an impact on energy consumption. Examples include space heating and water heating storage systems, cool storage systems, and load limiting devices in energy management systems. This category also includes programs that aggressively promote time-of-use (TOU) rates and other innovative rates such as real time pricing. These rates are intended to reduce consumer bills and shift hours of operation of equipment from on-peak to off-peak periods through the application of time differentiated rates.

Outage: 1) In a power system, the state of a component (such as a generating unit, transmission line, etc.) when it is not available to perform its function due to some event directly associated with the component. 2) An interruption in electric power. Causes can be man made or natural, purposeful or accidental. Also referred to as a Contingency.

Output Factor: The ratio of the actual energy output in the period of time considered, to the energy output which would have occurred if the machine or equipment had been operating at its full rating throughout its actual hours of service during the period.

Out-of-Phase: A condition existing when two waves are of the same frequency, but their maximum values do not occur at the same instant.

Overcurrent Relay: A protective relay that operates when its input current exceeds a predetermined value.

Over-Generation Condition: The system condition where the sum of the desired generation output, absent mitigation, would be greater than the system load.

Overhead Ground Wire: A protective wire strung above the conductors to shield the conductor from lightning.

Overload: Operating at higher than the rated power. In a power system, it can cause relaying of circuit breakers which switch equipment and parts of the system off line. In electronic circuits an overload may produce unwanted wave for distortion.

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Parallel: Two or more transmission lines, systems, or facilities whose alternating-current frequencies are exactly equal, operating in synchronism as part of the same electric system.

Partial Outage: The outage of a unit or plant auxiliary equipment which reduces the capability of the unit or plant without causing a complete shutdown. It may also include the outage of boilers in common header installations.

Participating Projects: Bureau of Reclamation water projects such as the Dolores and Seedskadee Projects that are financially linked to the CRSP according to the CRSP Act of 1956.

Particulate Matter: Solid particles, such as ash, which are released from combustion processes in exhaust gasses at fossil fuel plants.

Parties: The Transmission Provider and the Transmission Customer receiving service.

Path: A line or group of lines in which WSCC assigned as paths with numbers to differentiate them. Also referred to as a TOT.

Patrol, Helicopter: A scheduled or non-scheduled aerial inspection of transmission lines using a helicopter and crew consisting of pilot and journeymen linemen observer. Abnormal conditions of the transmission line are reported and corrective maintenance scheduled.

Peak Demand: The maximum load during a specified period of time.

Peak Load: The maximum electrical demand in a stated period of time. It may be the maximum instantaneous load or the maximum output of a generating plant or plants during a specified peak-load period.

Peak Load Plant: A plant usually housing old, low-efficiency steam units, gas turbines, diesels, or pumped storage hydroelectric equipment normally used during the peak-load periods. Also called Peaking Units.

Peaking Capacity: Capacity of generating equipment normally reserved for operation during the hours of highest daily, weekly, or seasonal loads. Some generating equipment may be operated at certain times as peaking capacity and at other times to serve loads on an around-the-clock basis.

Peaking Power: Sold during utilities' peak demand hours with a provision that an equal or greater amount of energy must be returned to Western during an off peak period. The customer is purchasing the ability to meet its consumers' instantaneous power needs when they are the greatest.

Penstock: The tube which carries the water from the forebay to the turbine of a hydroelectric plant.

Percent Difference: The relative change in a quantity over a specified time period. It is calculated as follows: the current value has the previous value subtracted from it; this new number is divided by the absolute value of the previous value; then this new number is multiplied by 100.

Performance Based Ratemaking (PBR): Regulated rates based on performances objectives, not actual costs.

Petroleum: A mixture of hydrocarbons existing in the liquid state found in natural underground reservoirs often associated with gas. Petroleum includes fuel oil No. 2, No. 4, No. 5, No. 6; topped crude; kerosene; and jet fuel.

Petroleum Coke: See Coke (Petroleum).

Petroleum (Crude Oil): A naturally occurring, oily, flammable liquid composed principally of hydrocarbons. Crude oil is occasionally found in springs or pools but usually is drilled from wells beneath the earth's surface.

PF: see Power Factor

Phase: The stage or progress of a cyclic movement such as current or voltage wave. Also a conductor which carries one of three separate phases (designated A, B, and C) of power in an Alternating Current system.

Phase Angle: In a power system, the displacement, in time, of the phase of one quantity from the phase of another, at power system frequency.

Phase Arrester: High-voltage devices connected between alternating current phases to prevent damage due to overvoltages.

Phase Conductor: In a multi-phase circuit, any conductor other than the neutral conductor.

Photovoltaic (PV) Cell: A type of semiconductor device in which the absorption of light energy creates a separation of electrical charges. This separation creates an electrical potential. The net effect is the direct conversion of light into electricity. Commercially available technologies range in efficiency from 8 to 27 percent. PV cells use several technologies, including single crystal silicon, multi crystalline or polycrystalline silicon, amorphous silicon, thin-film technology, concentrators, multi-generation cells, and dye-sensitized solar cells.

Photovoltaic (PV) Power System: A generating system that employs photovoltaic cells and other equipment to produce direct current or alternating current electrical power. Individual PV cells are packaged into modules that are then deployed in arrays to supply the desired voltage and current output. Approximately 100 square feet of modules are needed to produce 1 kilowatt of peak output. Arrays can consist of flat plate modules, or may employ concentrators to increase the efficiency of the PV modules. Another method of increasing system efficiency involves automatically tracking the movement of the sun. The efficiency of PV systems ranges from about 8 to 15 percent.

Pinch-Point: The FY in which the level of the rate is set as dictated by a revenue requirement in some future year to meet relatively large annual costs or to repay investments which come due.

Planned Generator: A proposal by a company to install electric generating equipment at an existing or planned facility or site. The proposal is based on the owner having obtained (1) all environmental and regulatory approvals, (2) a signed contract for the electric energy, or (3) financial closure for the facility.

Planned Outage: Generating units not in operation due to planned maintenance, scheduled closures, refueling, or other planned occurances.

Plant: A facility at which are located prime movers, electric generators, and auxiliary equipment for converting mechanical, chemical, and/or nuclear energy into electric energy. A plant may contain more than one type of prime mover. Electric utility plants exclude facilities that satisfy the definition of a qualifying facility under the Public Utility Regulatory Policies Act of 1978.
Base Load Plant: A power plant which is normally operated to carry base load and which, consequently, operates essentially at a constant load.
Fossil-Fuel Plant: An electric power plant utilizing fossil fuel , coal, lignite, oil, or natural gas, as its source of energy.
Hydroelectric Plant: An electric power plant utilizing falling water for the motive force of its prime mover.
Nuclear Power Plant: An electric generating station utilizing the energy from a nuclear reactor as the source of power.
Peak Load Plant: A power plant which is normally operated to provide power during maximum load periods.
Power Plant (Generating Station): A generating station at which are located prime movers, electric generators, and auxiliary equipment for producing electric energy.
Pumped Storage Plant: A power plant utilizing an arrangement whereby electric energy is generated for peak load use by utilizing water pumped into a storage reservoir usually during off-peak periods. A pumped storage plant may also be used to provide reserve generating capacity.
Run-of-River Plant: A hydroelectric power plant utilizing pondage or the flow of the stream as it occurs, as opposed to a reservoir impoundment of water.

Plant Factor: The ratio of the average load on the plant for the period of time considered to the aggregate rating of all the generating equipment installed at the plant.

Plant Use: The electric energy used in the operation of a plant. Included in this definition is the energy required for pumping at pumped storage plants.

Plant-Use Electricity: The electric energy used in the operation of a plant. This energy total is subtracted from the gross energy production of the plant; for reporting purposes the plant energy production is then reported as a net figure. The energy required for pumping at pumped storage plants is, by definition, subtracted, and the energy production for these plants is then reported as a net figure.

PMA: Power Marketing Administration

Point(s) of Delivery: Point(s) of interconnection on the Transmission Provider's Transmission System where capacity and/or energy transmitted by the Transmission Provider will be made available to the Receiving Party. The Point(s) of Delivery shall be specified in the Service Agreement.

Point-to-Point Transmission Service: The reservation and/or transmission of energy on either a firm basis and/or a non-firm basis from Point(s) of Receipt to Point(s) of Delivery, including any Ancillary Services that are provided by the Transmission Provider in conjunction with such service.

Point-to-Point Transmission Service Tariff: The Transmission Provider's Point-to-Point Transmission Service Tariff as such tariff may be amended and/or superseded from time to time.

Point(s) of Receipt: Point(s) of interconnection on the Transmission Provider's Transmission System where capacity and/or energy will be made available to the Transmission Provider by the Delivering Party. The Point(s) of Delivery shall be specified in the Service Agreement.

Pole Miles (of Line): Miles measured along the line of poles, structures, or towers carrying electric conductors regardless of the number of conductors or circuits carried.

Pole, Tubular Steel: Tapered steel tubes designed in the shape of a pole used primarily for aesthetic reasons as supports for electric transmission or distribution lines.

Pole Structure: In a transmission or communications system, a column (or columns) of tapered wood or steel, supporting overhead conductors on arms or brackets. In transmission, used at lower 115 or 230 kilovolt power levels.

Pole, Wood: Poles made of pine, larch, or cedar and treated with a preservative chemical against decay fungi. Wood poles are graded according to diameter of top and butt.

Polychlorinated Biphenyls (PCB): Any chemical substance that is limited to the biphenyl molecule that has been chlorinated to varying degrees or any combination of substances which contains such substance. Non-PCB Electrical Equipment is equipment that contains less than 50 ppm PCBs, anything over that amount is considered contaminated. Pure PCB is a term used for nonflammable insulating liquid in transformers and capacitors.

Pondage: The amount of water stored behind a hydroelectric dam of relatively small storage capacity used for daily or weekly regulation of the flow of a river.

Potential Peak Load Reduction: The amount of annual peak load reduction capability (measured in kilowatts) that can be deployed from Direct Load Control, Interruptible Load, Other Load Management, and Other DSM Program activities. It represents the load that can be reduced either by the direct control of the utility system operator or by the consumer in response to a utility request to curtail load. It reflects the installed load reduction capability, as opposed to the Actual Peak Reduction achieved by participants, during the time of annual system peak load.

Potential Transformer (PT): A small capacity transformer used to supply reduced voltage to volt meters, wattmeters, and relays.

Power: The rate at which energy is transferred. Electrical energy is usually measured in watts. Also used for a measurement of electrical capacity (in kilowatts or megawatts).

Power Circuit Breaker (PCB): A switching device that can interrupt a circuit in a power system under overload or Fault (short circuit) conditions, usually automatically tripped by protective relays. Power Circuit Breakers may use a vacuum, insulating oil, compressed air, or compressed gas as a medium for arc interruption. A PCB permits the opening of a power circuit under either normal or abnormal conditions. It allows equipment or transmission lines to be isolated from the system as required.

Power, Continuous: Hydroelectric power available from a plant on a continuous basis under the most adverse hydraulic conditions contemplated.

Power, Electric: The time rate of generating, transferring or using electric energy usually expressed in kilowatts.
Apparent: A quantity of power proportional to the mathematical product of the volts and amperes of a circuit. This product generally is divided by 1,000 and designated in kilovolt-amperes (kVA). It is comprised of both real and reactive power.
Firm: Power or power-producing capacity intended to be available at all times during the period covered by a commitment, even under adverse conditions.
Interruptable: Power made available under agreements which permit curtailment or cessation of delivery by the supplier.
Nonfirm: Power or power-producing capacity supplied or available under an arrangement which does not have the guaranteed continuous availability feature of firm power.
Reactive: See Reactive Power.
Real: The energy or work-producing part of “Apparent Power.” It is the rate of supply of energy, measured commercially in kilowatts. Also referred to as active power, as contrasted with reactive power.

Power Exchange (PX): An independent entity responsible for conducting an auction for generators seeking to sell energy and for loads which are not otherwise being served by bilateral contracts. A Power Exchange is responsible for scheduling generation in its scheduling (e.g., day-ahead, hour-ahead) markets, for determining hourly market clearing prices for its market, and for settlement and billing for suppliers and UDCs using its market.

Power Factor: The ratio of kilowatts (kW) to kilovolt amperes (kVA). A fraction, less than one, often expressed as a percentage, used to determine the electrical power in a circuit from the formula: watts=volts * amperes * power factor. It is equal to the cosine of the angle between the current and the voltage.

Power Flow: A generic term used to describe the type, direction, and magnitude of actual or simulated electrical power flows on electrical systems.

Power Flow Model: See Load Flow Model

Power Line Carrier: A communication system where the utility power line is used as the primary element in the communications link. Frequencies can range from 8kHz to 200 kHz and above. The system can be unidirectional or bidirectional and power levels are generally low ( in the 1 to 20 watt range).

Power Marketers: Power marketers are business entities engaged in buying and selling electricity, but do not own generating or transmission facilities. Power marketers, as opposed to brokers, take ownership of the electricity and are involved in interstate trade. These entities file with FERC for status as a power marketer.

Power Marketing Administration: (from RA6120.2) "Power marketing administration" means the Alaska Power Administration, the Bonneville Power Administration, the Southeastern Power Administration, the Southwestern Power Administration, or the Western Area Power Administration.

Power Pool: An association of two or more interconnected electric systems having an agreement to coordinate operations and planning for improved reliability and efficiencies.

Power Pool Designator: Two or more electric systems, which are interconnected and operated on a coordinated basis to achieve economics in supplying their combined loads. Power pool designator code indicates the following billing transaction is with a particular customer through the power pool arrangement.

Power Repayment Study: (from RA6120.2) "Power repayment study" means a study (previously referred to as an average rate and repayment study or repayment study) portraying the annual repayment of power production and transmission costs of a power system through the application of revenues over the repayment period of the power system. The study shows, among other items, estimated revenues and expenses, year by year, over the remainder of the power system's repayment period (based upon conditions prevailing over the cost evaluation period), the estimated amount of Federal investment amortized during each year, and the total estimated amount of Federal investment remaining to be amortized. The study does not deal with rate design. Power repayment studies may take two forms as described below:

  1. Current Power Repayment Study: A power repayment study that utilizes currently established rates for estimating future revenues. The study reflects the same basic power system included at the time rates were approved.
  2. Revised Power Repayment Study: A study that utilizes, in whole or in part, proposed or assumed rates for estimating future revenues. Typically, it is designed to demonstrate that potential revenue levels will satisfy the cost recovery criteria over the remainder of the power system's repayment period.

Power System (Electric): A group of one or more generating sources and connecting transmission lines operated under common management or supervision to supply load.
(from RA6120.2) A system comprised of one project or more than one project hydraulically and/or electrically integrated and therefore treated as one unit for the purpose of establishing rates.

Power System's Repayment Period: (from RA6120.2) A period extending to the final year allowed under the cost recovery criteria for amortization of the original investment in all projects included in the power repayment study.

Preference Customers: In accordance with Congressional directives, cooperatives and public bodies (states, public utility districts, counties, municipalities, irrigation districts, Native American tribes, and Federal customers) have preferential rights to Federally generated hydro-power. These customers fall into two categories:

  1. those that have no generating facilities of their own or other sources of power depend on WAPA for their entire power supply; and
  2. those that supplement their own power resources with purchases from WAPA.

The Power rate schedules are similar for these two classes of customers.

Price: The amount of money or consideration- in- kind for which a service is bought, sold, or offered for sale.

Primary Distribution Feeder: A primary voltage distribution circuit, usually considered to be between a substation or point of supply and the distribution transformers, which supply lower voltage distribution circuits or consumer service circuits.

Primary Voltage: The voltage of the circuit supplying power to a transformer is called the primary voltage, as opposed to the output voltage or load-supply voltage which is called the secondary voltage. In power supply practice, the primary is almost always the high-voltage side of a transformer and the secondary the low-voltage side of a transformer, except at a generating station.

Prime Mover: The engine, turbine, water wheel, or similar machine that drives an electric generator; or, for reporting purposes, a device that converts energy to electricity directly (e.g., photovoltaic solar and fuel cells).

Process Heating: Energy Efficiency program promotion of increased electric energy efficiency applications in industrial process heating.

Production: The act or process of generating electric energy. Also a functional classification relating to that portion of a utility plant used for the purpose of generating electric energy, or to expenses relating to the operation or maintenance of a production plant, or the purchase and interchange of electric energy.

Production Cost: The cost of producing electric power to serve load.

Production Cost Model: A software package designed to project the cost of producing electric power to serve load in the future, normally including some representation of hourly loads and generating resources, along with an economic dispatch algorithm.

Profit: The income remaining after all business expenses are paid.

Project: Defined by authorizing legislation and made up of feature(s) within a Regional Office(s) (e.g., CRSP, Parker-Davis, Big Thompson, Pick- Sloan, etc.).

Project Use Power: Electricity needed to pump water or to power other features of a Federal irrigation projects.

Protection: All switching, tagging, or other work done to make a given piece of equipment safe to work on.

Protective Relay: A device whose function is to detect defective lines or apparatus or other power system conditions of an abnormal or dangerous nature and to initiate appropriate control action.

Protective Scheme: A group of interrelated devices used to prevent damage to equipment by extraordinarily high voltages or currents.

Provisional Rate: A rate that has been confirmed, approved, and placed into effect on an interim basis by the Deputy Secretary of Energy.

PRP: Provo River Project

PRS: Power repayment study.

PST: Phase-Shifting Transformer

Public Authority Service to Public Authorities; Public authority service includes electricity supplied and services rendered to municipalities or divisions or agencies of State or Federal governments, under special contracts or agreements or service classifications applicable only to public authorities.

Public Street and Highway Lighting: Public street and highway lighting includes electricity supplied and services rendered for the purposes of lighting streets, highways, parks, and other public places; or for traffic or other signal system service, for municipalities, or other divisions or agencies of State or Federal governments.

Public Utility District (PUD): A political subdivision (quasi-public corporation of a state), with territorial boundaries embracing an area wider than a single municipality (incorporated as well as unincorporated) and frequently covering more than one county, for the purpose of generating, transmitting, and distributing electric energy.

PUHCA: Public Utility Holding Company Act (1935)

Pumped Storage: An arrangement whereby a reservoir is filled with water by pumping during off-peak periods when low-cost steam energy is available or when water is being spilled at other hydro plants. This method of operating a hydro plant stores water which can be used to meet peak loads.

Pumped Storage Hydroelectric Plant: A plant that usually generates electric energy during peak-load periods by using water previously pumped into an elevated storage reservoir during off-peak periods when excess generating capacity is available to do so. When additional generating capacity is needed, the water can be released from the reservoir through a conduit to turbine generators located in a power plant at a lower level.

Purchase Power: Power that Western must buy from other suppliers when not enough Federal generation is available.

Purchased Power Adjustment: A clause in a rate schedule that provides for adjustments to the bill when energy from another electric system is acquired and it's cost varies from a specified unit base amount.

Pure Pumped Storage Hydroelectric Plant: A plant that produces power only from water that has previously been pumped to an upper reservoir, as opposed to a plant that also receives runoff from a river or other natural water source.

PURPA: Public Utility Regulatory Policy Act (1979?)

PV: Photovoltaic. See Photovoltaic Cell and Photovoltaic Power System.

PX: see Power Exchange

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Q1: First quarter of the year, the months January, February, and March

Q2: Second quarter of the year, the months April, May, and June.

Q3: Third quarter of the year, the months July, August, and September.

Q4: Fourth quarter of the year, the months October, November, and December.

Quad: 10 to the 15th power, or one quadrillion. In energy terms, a quad is one quadrillion Btu.

Qualified (or Qualifying) Facility (QF): A cogeneration or small power production facility that meets certain ownership, operating, and efficiency criteria established by the Federal Energy Regulatory Commission (FERC) pursuant to the Public Utility Regulatory Policies Act (PURPA). (See the Code of Federal Regulations, Title 18, Part 292.)

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RA6120.2: Order by the Secretary of Energy entitled "Power Marketing Administration Financial Reporting." The purpose of RA6120.2 is: "To establish financial reporting policies, procedures, and methodology for all Department of Energy (DOE) power marketing administrations (PMA's) except, where deviations, therefrom are specifically approved by the Secretary, authorized by statute, or identified and explained in a transmittal memorandum or in the footnotes to the reports."

Radial Line: A power transmission circuit fed from one end only.

Railroad and Railway Services: Railroad and railway services include electricity supplied and services rendered to railroads and interurban and street railways for general railroad use, including the propulsion of cars or locomotives, where such electricity is supplied under separate and distinct rate schedules.

Ramp-Rate: The rate of change (increase or decrease) in water release volume from a hydroelectric power plant, usually expressed as CFS per hour.

Ramping: Changing the loading level of a generator in a constant manner over a fixed time (i.e. ramping up or ramping down). Such changes may be directed by computer or by manual control.

RAS: Remedial Action Scheme

Ratchet Demand Clause: A clause in a rate schedule that provides that maximum past or present demands be taken into account to establish billings for a given period.

Rate Base: The value of property upon which a utility is permitted to earn a specified rate of return as established by a regulatory authority. The rate base generally represents the value of property used by the utility in providing service and may be calculated by any one or a combination of the following accounting methods: fair value, prudent investment, reproduction cost, or original cost. Depending on which method is used, the rate base includes cash, working capital, materials and supplies, and deductions for accumulated provisions for depreciation, contributions in aid of construction, customer advances for construction, accumulated deferred income taxes, and accumulated deferred investment tax credits.

Rate Brochure: A document explaining the rationale and background of a rate proposal.

Rate Class: A group of customers identified as a class and subject to a rate different from other groups.

Ratemaking Authority: A utility commission's legal authority to fix, modify, approve, or disapprove rates, as determined by the powers given the commission by a State or Federal legislature.

Rate-Setting PRS: A PRS used for a rate adjustment proposal.

Rates, Lifeline: A standard definition of lifeline rates as applied to electricity service does not exist. The advocates of lifeline rates generally propose a low or reduced flat rate applicable to the first several hundred kilowatthours (kWh) consumed monthly by each residential customer or a special group of residential customers. Revenue lost because of charging the low lifeline rates may be recovered by raising rates for consumption by residential customers consuming beyond the lifeline level and/or by increasing rates for nonresidential classes.

Rating: Limits placed on operating conditions of a machine, transmission line, apparatus, or device based on its design characteristics. Such limits as load, voltage, temperature, and frequency may be given in the rating.

Reactance: A physical property of a circuit component which tends to hinder the flow of alternating current.

Reactive Power: In an AC circuit, the current generally leads or lags the voltage. Thus, the current consists of an active component, in phase with the voltage, and an out-of-phase, or reactive, component. The active component, measured in watts (voltage times in-phase current), is the part that powers equipment. The reactive power, measured in volt-amperes reactive (VAr), represents the energy stored in electric or magnetic fields. (These relations often are depicted as a right-angle triangle, where apparent power is the hypotenuse and active and reactive power are the other two sides.) Reactive power is consumed or absorbed in the magnetic field of inductive equipment; it is produced or generated in capacitive equipment. Induction motors consume it because of their magnetizing current requirements (consumption even at no load) and the inductive reactance in their windings. Shunt capacitor banks produce it. Field winding excitation control makes synchronous generators either produce it or absorb it. Reactive power consumption tends to depress transmission voltage, while its production or injection tends to support voltage. Transmission lines both consume it (because of their series inductance) and produce it (from their shunt capacitance). Because transmission line voltage is held relatively constant, the production of reactive power is nearly constant. Its consumption, however, is low at light load and high at heavy load. The variable net reactive-power requirements of a transmission line give rise to a voltage control problem. Generators and reactive-power compensation equipment must absorb reactive power during light load, and produce it during heavy load. In a general emergency, when there are outages and high loading on remaining transmission lines, those lines consume reactive power that must be supplied by nearby generators and shunt capacitance banks. (Reactive power can be transmitted only over relatively short distances.) If reactive power cannot be supplied promptly enough in an area of decaying voltage, voltage may in effect collapse. Insufficient voltage support may in addition contribute to synchronous instability. - explanation by Carson W. Taylor of the Bonneville Power Administration, taken from an article in the June 1999 issue of the IEEE Spectrum.

Reactor: A component consisting of a coil of wire that inserts inductive reactance into the system for power factor control

Real-Time Market: The competitive generation market controlled and coordinated by the power system operator for arranging real-time imbalance power.

Receipts: Purchases of fuel.

Receiving Party: The entity receiving the capacity and/or energy transmitted by the Transmission Provider to the Point(s) of Delivery.

Reclamation: Bureau of Reclamation, U.S. Department of the Interior.

Reclamation Law: A series of Federal laws. Viewed as a whole, these laws create the originating framework under which Western markets power. More generally, the laws that define what the Bureau of Reclamation is authorized to do.

Reclamation Method: Refers to an interest offset calculation method used by the Bureau of Reclamation and subsequently used by Western. This method calculates ½ year's interest credit and then applies the revenue towards repayment of the investments.

Reclose: The automatic closing of a power circuit breaker following an opening operation via protective relay action.

Reclosing Device (Recloser): A control device which initiates the reclosing of a circuit after it has been opened by a protective relay.

Redispatch: The readjustment of generation output schedules or demand side management, generally to relieve transmission congestion.

Regional Transmission Group: A voluntary organization of transmission owners, transmission users, and other entities approved by the Commission to efficiently coordinate transmission planning (and expansion), operation, and use on a regional (and interregional) basis.

Regulated Frequency: Frequency which, over a period of time, is regulated to maintain the average frequency at some predetermined value. This must be done in such a way that the deviations from the pre-determined value are always small.

Regulation: Politically: The government function of controlling or directing economic entities through the process of rulemaking and adjudication.
Electrically: Regulation is the amount of operating reserve capacity (part of spinning reserve) required by the control area to respond to automatic generation control to assure that the area control error (ACE) equals zero at least one time in all ten minute periods and be within specified limits in order to manage the inadvertent flow of energy between control areas. Sometimes referred to as Regulating Capacity.

Regulating Reserve: An amount of spinning reserve responsive to AGC, which is sufficient to provide normal regulating margin. The portion of Operating Reserve that is allocated to respond to AGC requirements.

Regulating Reserve Margin: Regulating Reserves sufficient to allow a Control Area to meet NERC's Control Performance Criteria CPS-1 and CPS-2.

Relay: An electrical device designed to interpret input conditions (which reflect the operation of another piece of equipment) in a prescribed manner, and, after specified conditions are met, to respond to cause contact operations or similar abrupt change in a circuit controlling the equipment. Closing of a relay contact energizes a circuit that acts to trip a Power Circuit Breaker to open a power system circuit and de-energize a faulted component or transmission line.

Relay, Differential: A protectove relay that by its design or application is intended to respond to the difference between incoming and outgoing quantities associated with the protected apparatus. Protected apparatus may be a power transformer or generator.

Relay, Ground: A protective relay that by its design or application is intended to respond primarily to system ground faults. Ground relays may be over-current, distance or combinations thereof, with or without directional discrimination.

Relay, Overcurrent: A protective relay that operates when the current through the relay, during its operating period, is equal to or greater than its setting. Over-current relays are usually a combination of instantaneous and time delay units with or without directional discrimination.

Relay, Protective: An electro-mechanical, electronic, or digital device whose function is to detect defective lines or apparatus or other power system conditions of an abnormal or dangerous nature and to initiate appropriate control action, such as opening circuit breakers. Usually referred to as a Relay.

Relay, Reclosing: A programming relay whose function is to initiate the sequence of actions leading to automatic reclosing of a circuit breaker.

Relay, Undercurrent: A relay that operates when the current is less than a predetermined value.

Reliability: An electric utility's ability to deliver uninterrupted electricity to its customers upon demand, to whatever degree required. Reliability consists or two criteria: generation system reliability and transmission/distribution system reliability. May be measured by the frequency, duration, and magnitude of adverse effects on the electric supply.

Reliability Criteria: Principals used to design, plan, operate, and assess the actual or projected reliability of an electric system.

Reliability Must Run (RMR) Generation: The minimum generation (number of units or MW output) required by the power system operator to be on line to maintain system reliability

Remote Meter Reading System: A telemetry system capable of reading a meter (e.g., watthour, demand, gas, or water meter) and collecting the data at a collection point.

Renewable Energy (Resources): See Energy, Renewable.

Replacement: The substitution of a unit of Utility Plant for another unit generally of a like or improved character.

Replacement Cost: An estimate of the cost to replace the existing facilities either as currently structured or as redesigned to embrace new technology with facilites that will perform the same functions. This method recognizes the benefits of presently available technology in replacing the system. For example, a number of smaller generator units may be replaced with a single large unit at lower unit costs and greater efficiency.

Reportable Disturbance: 80% of the Most Severe Single Contingency loss of a Control Area or Reserve Sharing Group, or some lower threshold selected on a regional basis

Repowering: A means of increasing the output and efficiency of conventional thermal generating facilities. For example, adding combustion turbines to supplement or replace steam from fuel combustion used to power steam turbines.

Reserve, Electrical: The capability in excess of that required to carry the system load.

Reserve Margin (Operating): The amount of unused available capability of an electric power system at peak load for a utility system as a percentage of total capability.

Reserve, Spinning: That Operating Reserve connected to the bus and ready to take load.

Reservoir Storage: The volume of water in a reservoir at a given time.

Residential: The residential sector is defined as private household establishments which consume energy primarily for space heating, water heating, air conditioning, lighting, refrigeration, cooking, and clothes drying. The classification of an individual consumer's account, where the use is both residential and commercial, is based on principal use.

Residual Fuel Oil: The topped crude of refinery operation, includes No. 5 and No. 6 fuel oils as defined in ASTM Specification D396 and Federal Specification VV-F-815C; Navy Special fuel oil as defined in Military Specification MIL-F-859E including Amendment 2 (NATO Symbol F-77); and Bunker C fuel oil. Residual fuel oil is used for the production of electric power, space heating, vessel bunkering, and various industrial purposes. Imports of residual fuel oil include imported crude oil burned as fuel.

Resource Capacity: Generation, Load, Interchange, or any system component that can be used to modify the Control Area's ACE.

Resource Pools: Power withdrawn from current Western customers and offered to new customers at specific intervals during a contract period.

Restricted-Universe Census: This is the complete data enumeration from a specifically defined subset of entities including, for example, those that exceed a given sales level or generator nameplate capacity.

Retail or Retail Sales: Sales covering electrical energy supplied for residential, commercial, and industrial end-use purposes. Other small classes, such as agriculture and street lighting, also are included in this category. The electric energy sales made by a Retailer to end-use customers.

Retail Load: The load that is the responsibility of a retailer.

Retailer: An entity who purchases power on behalf of end-use customers. This can be a marketer, broker, scheduling coordinator, buyer, or a UDC.

Revenue: The total amount of money received by a firm from sales of its products and/or services, gains from the sales or exchange of assets, interest and dividends earned on investments, and other increases in the owner's equity except those arising from capital adjustments.

Revenue Requirement: The revenue level required by Western to cover annual expenses, such as O&M, purchase power, transmission service expenses, interest, deferred expenses, and repayment of Federal investments, and other assigned costs.

Reversible Turbine: A hydraulic turbine, normally installed in a pumped storage plant, which can be used alternately as a pump and prime mover.

RFP: Request for Proposals

Right-of-Way: An easement for a certain purpose over the land of another, such as the strip of land used for a road, electric transmission line, ditch , pipeline, etc. WAPA usually acquires easements for its transmission lines, roads, and other facilities such as guys and anchors.

RIN: Real-time Information Network

Ring Bus Scheme: Arrangement of substation circuit breakers that has one breaker for each line position, with a single bus closed back on itself, to form a ring. A ring bus is generally capable of handling 4-6 positions. The current transfer through the breakers when the ring is open, however, limits its application.

Rio Grande Project: A Federal multipurpose water project located in south-central New Mexico near the city of Truth or Consequences. The major features of the project are Elephant Butte Dam, Powerplant, and Reservoir, and Caballo Dam and Reservoir.

RIP: Recovery Implementation Program, a program for the recovery of Federally-designated endangered-fish species in the Colorado River and its tributaries.

RMR: Reliability must-run, also the Rocky Mountain Region of the Western Area Power Administration.

RMRG: Rocky Mountain Reserve Group

ROD: Record of Decision (of an Environmental Impact Statement)

Rolling (Rotating) Blackout: Controlled recurring outages across a region designed to prevent a system disturbance when power demand is greater that the available generation or transmission capacity.

ROW: Right of Way

RPA: Reasonable and Prudent Alternative

RSG: Reserve Sharing Group - Control Areas may pool their Contingency Reserves by joining a Reserve Sharing Group (RSG).

RTA: Regional Transmission Association

RTG: Regional Transmission Group

RTU: Remote Terminal Unit, the portion of a SCADA system located in a substation, powerplant, or other power system facility. The RTU is electrically connected to the switches, controls, guages, and sensors in the facility where it is located, and communicates with the SCADA computer located at the Control Center.

Rule Curve: A seasonal guide to the use of reservoir storage.

Run of River Plant: A hydroelectric power plant using the flow of the stream as it occurs and having little or no reservoir capacity for storage of water. Sometimes called a "Stream Flow" powerplant.

Run or Lose Generation: Hydro generation that has no storage capacity and if backed down, would spill; also hydro generation where storage capacity is exceeded and spilling even though the generators are at full output; and hydro generation where storage capacity is inadequate to prevent loss of hydro energy either immediately or during the forecast period if hydro output is reduced.

Running and Quick-Start Capability: The net capability of generating units that carry load or have quick-start capability. In general, quick-start capability refers to generating units that can be available for load within a 30-minute period.

Rural Electric Cooperative: Generally a non-profit, customer-owned electric utility responsible for distributing power in mostly rural areas. Sometimes referred to as an REA, the acronym for the Rural Electric Administration, a Federal agency (now called Rural Utility Services [RUS]) that oversees and loans money to rural electric cooperatives.

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Safe Clearance Procedure: The method which shall be followed in requesting, placing, issuing, transferring, releasing, and removing a clearance.

Sag, Conductor: The distance the conductor droops below a straight line between adjacent points of support.

Sales: The amount of kilowatt-hours sold in a given period of time; usually grouped by classes of service, such as residential, commercial, industrial, and other. Other sales include public street and highway lighting, other sales to public authorities and railways, and interdepartmental sales.

Sales for Resale: Energy supplied to other electric utilities, cooperatives, municipalities, and Federal and State electric agencies for resale to ultimate consumers.

SCADA (Supervisory Control and Data Acquisition): A centralized remote control system which includes the transmission of numerical quantities and alarms to and from generation stations, substations, and other electrical facilities to a Control Center.

Schedule Imbalance Deviation: The deviation between metered and scheduled delivery or consumption.

Scheduling Coordinator: An entity authorized to submit to the power system operator a balanced generation or demand schedule on behalf of one or more generators, and one or more end-users customers.

Scheduling Market: The pre-planning of generation and load schedules in advance of delivery. This is typically done one full working day in advance and is often called pre-scheduling:

Scheduled Outage: The shutdown of a generating unit, transmission line, or other facility, for inspection or maintenance, in accordance with an advance schedule.

Scoping: A process for determining the range of issues to be addressed in an environmental impact statement and for identifying the significant issues related to a proposed action. As part of the scoping process, the agency invites the participation of affected Federal, State, and local agencies; affected groups and individuals; and the general public.

Scroll Case: A device which conducts the water from the penstock around the turbine runner in a hydroelectric system.

Seasonal Diversity: Diversity between two or more power systems which occurs when their annual peak loads are in different seasons of the year, e.g., winter-peaking versus summer-peaking utilities.

Seasonal Power: Power generated or made available to customers only during certain seasons of the year.

Seasonal WRP: Seasonal Western Replacement Power is power purchased by Western on behalf of a customer/contractor for a period of one six-month season, and is part of the customer/contractor’s CROD during that season.

Secondary Distribution System: A low-voltage, alternating-current system which connects the secondaries of distribution transformers to the customer's services.

Secondary Energy: A term generally applied to energy available from Non-Firm Power.

Secondary Voltage: The output or load-supply voltage of a transformer or substation in power supply practice, the secondary is almost always the low-voltage side of a transformer.

Secretary: (from RA6120.2) The Secretary of Energy.

Seller: An entity that produces or arranges for the production of electrical energy.

Series Capacitors: A bank of capacitors connected in series with an electrical transmission line which is used to compensate the reactive portion of line impedance.

Service Agreement: The initial agreement and any supplements thereto entered into by the Transmission Customer and the Transmission Provider for service.

Service Area: Territory in which a utility system is required or has the right to supply electric service to ultimate customers.

Service Drop: The overhead conductors between the electric supply, such as the last pole, and the building or structure being served.

Service Entrance: The equipment installed between the service drop or lateral, and the customer's conductors. Typically consists of a meter used for billing, switches and/or circuit breakers and/or fuses and a metal housing.

Service Lateral: The underground service conductors between the street main and the first point of connection to the service entrance conductors.

Service Life: The time between the date electric plant is includible in electric plant in service, or electric plant leased to others, and the date of its retirement. If depreciation is accounted for on a production basis rather than on a time basis, then service life should be measured in terms of the appropriate unit of production.

Settlement: A financial settlement process (billing and payment) for products and services purchased and sold; each settlement will involve a price and a quantity.

Short Circuit: An abnormal connection between two or more points in a circuit by a conducting path of low resistance. The short circuit may either be deliberate as in a protective grounding, or accidental as in a system fault.

Short Ton: A unit of weight equal to 2,000 pounds.

SHP: See Sustainable Hydro Power

Shunt: A device having resistance or impedance connected in parallel across other devices or apparatus, and diverting some of the current from it.

Shunt Capacitor Banks: A system of capacitors to supply vars to the connected alternating current system to compensate for the reactive power consumed on power equipment. Capacitors connecting from a power line to a grounded connection, usually designed to improve the system's power factor.

Shunt Var Controller (SVC): Shunt Capacitor Banks that include electronic switching and controls to continuously vary the amount of vars supplied to the power system.

Sinking Fund: Cash or other assets, and the interest or other income earned thereon, set apart for the retirement of a debt, the redemption of a stock or the protection of an investment in depreciable property.

SLCA/IP: The Salt Lake City Area/lntegrated Projects, which encompass the combined sales and resources of the CRSP, Collbran, Dolores, Rio Grande, and Seedskadee Projects.

SLIP: A shortened abbreviation sometimes used for SLCA/IP .

Small Power Producer (SPP): Under the Public Utility Regulatory Policies Act (PURPA), a small power production facility (or small power producer) generates electricity using waste, renewable (water, wind, and solar), or geothermal energy as a primary energy source. Fossil fuels can be used, but renewable resource must provide at least 75 percent of the total energy input. (See Code of Federal Regulations, Title 18, Part 292.)

Solar Cell: See Photovoltaic Cell

Solar Power: See Photovoltaic Power System

Spacer: Mechanical device attached to each subconductor of a conductor bundle to prevent physical contact of the subconductors.

Span: The horizontal distance between two adjacent supporting points of a conductor (i.e., between transmission towers).

Spark Spread: The profit realized by converting fuel to electricity in a power plant.

Speed Governor: A device for controlling the speed of an electric generator.

Spillway: The channel or passageway around or over the dam through which excess water is “spilled” past the darn without passing through the turbines.

Spinning Reserve: That reserve generating capacity running at a zero load, connected to an output bus, synchronized to the electric system, and ready to take immediate load. The portion of unloaded synchronized generating capacity, controlled by the power system operator, which is capable of being loaded in 10 minutes, and which is capable of running for at least two hours.

Spot Market: see Real-Time Market

Spot Purchases: A single shipment of fuel or volumes of fuel, purchased for delivery within 1 year. Spot purchases are often made by a user to fulfill a certain portion of energy requirements, to meet unanticipated energy needs, or to take advantage of low fuel prices.

Stability: The property of a system or element by virtue of which its output will ultimately attain a steady state. The amount of power that can be transferred from one machine to another following a disturbance. The stability of a power system is its ability to develop restoring forces equal to or greater than the disturbing forces so as to maintain a state of equilibrium.

Stage 1 Alert: A power alert issued by the California Independent System Operator (CAISO). The state's operating reserves of energy have dipped below 7 percent. All power consumers are asked to conserve energy. A Stage 1 emergency is declared when the CAISO determines there will be an operating reserve shortfall within the next two hours. It is less severe than a stage 2 or stage 3 emergency. Stage 1 does not require interruption of service to customers.

Stage 2 Alert: A Stage 2 emergency is declared anytime there will be a serious operating reserve shortfall (less than 5%) within the next two hours. At this stage, interruption of service to some or all of selected customers is required. Many customers have agreed to be interrupted in case of a stage 2 emergency. These customers receive a reduced rate for their electrical service as compensation for their agreement to be curtailed.

Stage 3 Alert: A Stage 3 emergency is declared anytime there will be a critical operating reserve shortfall (less than 1½%) within the next two hours. Stage 3 is the most severe emergency and indicates that, without significant ISO intervention, the electrical system is in danger of imminent collapse. Involuntary curtailment of service to consumers (i.e. "rolling blackout") is required to maintain operating reserve above 1½%.

Standard Industrial Classification (SIC): A set of codes developed by the Office of Management and Budget, which categorizes business into groups with similar economic activities.

Standby Facility: A facility that supports a utility system and is generally running under no load. It is available to replace or supplement a facility normally in service.

Standby Service: Support service that is available, as needed, to supplement a consumer, a utility system, or to another utility if a schedule or an agreement authorizes the transaction. The service is not regularly used.

Startup: The term used to describe the procedure to start the prime mover and support auxiliaries; includes synchronizing and loading the generator. For nuclear units, involves an increase in the rate of fission (and heat production) in a nuclear reactor usually by the removal of control rods from the core.

Startup Service (Black Start Service): Providing the electrical power needed to start up a generating plant, usually after a system emergency that causes loss of electricity to the generating station.

Station Use: The kilowatthours used at an electric generating station for such purposes as excitation and operation of auxiliary and other facilities essential to the operation of the station. Station use includes electric energy supplied from house generators, main generators, the transmission system, and any other sources for this purpose. The quantity of energy used is the difference between the gross generation plus any supply from outside the station and the net output of the station.

Station Service: The electrical source, equipment, and facilities that provide station use power. Station service is sometimes used synonomously with station use.

Steam Electric Plant (Conventional): A plant in which the prime mover is a steam turbine. The steam used to drive the turbine is produced in a boiler where fossil fuels are burned.

Step Down: To change electricity from a higher to a lower voltage.

Step Up: To change electricity from a lower to a higher voltage.

Stocks: A supply of fuel accumulated for future use. This includes coal and fuel oil stocks at the plant site, in coal cars, tanks, or barges at the plant site, or at separate storage sites.

Storage:
Dead: The volume of water remaining in a reservoir after all the usable storage has been withdrawn.
Gross: The total volume of water in a reservoir at normal full pool.
Seasonal: Water held over from the annual high-water season to the following low-water season.
Usable (or Live): The volume of storage in a reservoir which can be withdrawn for various conservation or power production purposes (gross storage minus dead storage).

Storage Project: A project with a reservoir of sufficient size to carry over from the high-flow season to the low-flow season (or years) and thus develop a firm flow substantially more than the minimum natural flow. A storage project may have its own powerplant or may be used only for increasing generation at a downstream plant.

Stream Flow: The rate at which water passes a given point in a stream, usually expressed in cubic feet per second (CFS).

String Suspension: A string of insulators suspended from a tower structure cross arm for the purpose of supporting the conductor; may be single, double, or “vee” strings depending on tower design.

Subbituminous Coal: Subbituminous coal, or black lignite, is dull black and generally contains 20 to 30 percent moisture. The heat content of subbituminous coal ranges from 16 to 24 million Btu per ton as received and averages about 18 million Btu per ton. Subbituminous coal, mined in the western coal fields, is used for generating electricity and space heating.

Submetering: Remetering of purchased energy by a customer for distribution to his tenants through privately owned or rented meters.

Substation: An assemblage of equipment for the purpose of switching and/or changing or regulating the voltage of electricity. Service equipment, line transformer installations, or minor distribution and transmission equipment are not classified as substations.

Subtransmission: A functional classification relating to that portion of utility plant used for the purpose of distributing electric energy in bulk from convenient points on the transmission system to the distribution system and in some cases to ultimate consumers.

Sulfur: One of the elements present in varying quantities in coal which contributes to environmental degradation when coal is burned. In terms of sulfur content by weight, coal is generally classified as low (less than or equal to 1 percent), medium (greater than 1 percent and less than or equal to 3 percent), and high (greater than 3 percent). Sulfur content is measured as a percent by weight of coal on an "as received" or a "dry" (moisture-free, usually part of a laboratory analysis) basis.

Summer Peak: The greatest load on an electric system during any prescribed demand interval in the summer (or cooling) season, usually between June 1 and September 30.

Summer Season: Designated months of delivery of capacity and/or energy, those months being: CRSP MC and RMR use April through September; UGP uses May through October; and Parker Davis (DSWR) uses March through September.

Supervisory Control and Data Acquisition (SCADA): A computer system that allows an electric system operator to remotely monitor and control elements of an electric system. A centralized remote control system that includes the transmission of numerical quantities and alarms to and from substations, generating stations, and control centers.

Surge Arrestor: A device designed to protect electric equipment from high transient voltage by diverting to ground a momentary high voltage surge (lightning usually). Usually connected between the conductor and ground. The lightning arrester is designed to allow the surge voltage to dissipate and then to restore itself to its initial non-conducting state. Dissipation of surge voltages permits substantial savings in transformers and other equipment by reducing the insulation required.

Surplus Capacity: The difference between assured system capacity and the system peak load for a specified period.

Suspension Clamp: The conductor support on transmission-line suspension structures. Attaches to the insulator string.

Sustainable Hydro Power (SHP) A fixed level of long term capacity and energy available from the SLCA/IP facilities during the summer and winter seasons, based on an established risk level. SHP represents the minimum amount of capacity and energy that Western is required to provide to customers under their firm power contracts.

Swing: The tendency of some part of a power system to move toward a condition of being out-of-step with another part of the system, usually as a result of a Disturbance.

Switchgear: Substation equipment designed and operated to switch electrical circuits and to interrupt power flow.

Switching, General: Switching performed for line sectionalizing or system rearrangement for testing and/or changes in operating conditions. Such operations are not normally associated with Clearances, Hot Line Orders or Special Conditions.

Switching Order: A form on which the switchman writes the details of the switching to be performed.

Switching Program Form: A form that formalizes and documents each step in the process of establishing and releasing clearances, hot line orders, special conditioning, and performing general switching.

Switching Station: Facility equipment used to tie together two or more electric circuits through switches. The switches are selectively arranged to permit a circuit to be disconnected, as in case of trouble, or to change the electric connection between the circuits. A type of substation.

Switchman: Any person authorized to perform switching and tagging operations. Those authorized may include dispatchers, foremen, operators, linemen, electricians, technicians, and plant mechanics.

Switchyard: The outdoor portion of a substation.

SWRTA: Southwestern Regional Transmission Association. SWRTA merged with WSCC and WRTA to create WECC.

Synchronized Operation: An operation wherein power facilities are electrically connected and controlled to operate at the same frequency. It is synonymous with operation in parallel.

System (Electric): Physically connected generation, transmission, and distribution facilities operated as an integrated unit under one central management, or operating supervision.

System Disturbance: A regional blackout.

System Frequency: Frequency in hertz (cycles per second) of a power system's alternating voltage. Nominal high-voltage power system frequency in North America is 60 hertz.

System Interconnection: A connection between two electric systems permitting the transfer of electric energy in either direction.

System Reliability: see Reliability

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T&D: Transmission and Distribution

TAG: Technical Assessment Guide (published by EPRI)

Tailwater: The water surface immediately downstream from a dam of hydroelectric powerplant.

Tap: To tie a substation into an existing line by simply running a new single circuit line from the substation to the existing line and tying into it; tapping feeds only a portion of the power carried on the line to the substation.

Tap Changers: Devices in some transformers that increase or reduce the potential by changing the transformer turns ratio. Tap changing transformers are used to control voltage at loads, substations, and direct current ties.

Tariff: A document filed with the appropriate regulatory authority specifying lawful rates, charges, rules, and conditions under which the utility provides services to parties. A tariff typically includes rates schedules, list of contracts, rules and sample forms.

Tensioning: Pulling the conductors to the correct sag so that proper ground clearance is maintained as well as to ensure that the supporting structures are not overloaded under design, ice, and wind conditions.

Therm: A measure of the heat content of gas equal to 100,000 btu. One therm of natural gas is equivalent to 100 cubic feet of gas at standard temperature and pressure (60 degrees F, and 14.73 pounds/square inch.)

Thermal: A term used to identify a type of electric generating station or power plant, or the capacity thereof, in which the source of energy for the prime mover is heat.

Thermal Pollution: Rise in temperature of water such as that resulting from heat released by a thermal plant to cooling water when the effects on other uses of the water are detrimental.

Thermal Powerplant: Any electric power plant which operates by generating heat and converting the heat to electricity.

Thermal Sag: The amount of sag in transmission line conductors and static wires between structures due to line expansion from hot weather or from high loading on the line.

Thermionic Device: A device which converts heat into electicity by "boiling" electrons from a metal surface and condensing them on a cooler surface.

Thermoelectric Device: A device in which metals at two different temperatures are placed in contact. There is a difference in electrical potential between the two, and a current of electricity flows.

Three-Shot Recloser: A protective relay scheme which will close a power circuit breaker three times in succession when a permanent Fault exists.

Tidal Power: Energy obtained from the filling and emptying of a bay or estuary that can be closed by a dam.

Tie Line: A transmission line connecting two or more power systems.

Time-of-Day Metering: A method or system for recording kilowatthours consumed, or a maximum demand established during a specified period of time such as on-peak or off-peak periods.

Time-of-Day (Time-of-Use) Pricing: Pricing of service during periods of the day based on the cost of supplying the service during those periods.

Time-of-Season Pricing: Pricing of service during seasons of the year based on the cost of supplying the service during those seasons.

Time-Overcurrent Relay: An overcurrent protective relay in which the input current and operating time are inversely related throughout a substantial portion of the performance range. The higher the input current the more quickly the relay operates.

Time Zone Diversity: Diversity between power systems in different time zones resulting from time difference as it affects the demand for power.

Total DSM Cost: Refers to the sum of total utility cost and nonutility cost for DSM.

Total DSM Programs: Refers to the total net effects of all the utility's DSM programs. It is the sum of the effects for Energy Efficiency, Direct Load Control, Interruptible Load, Other Load Management, Other DSM Programs, and Load Building. Net growth in energy or load effects should be reported as a negative number, shown with a minus sign.

Total Nonutility Costs: Refers to total cash expenditures incurred by consumers and trade allies that are associated with participation in a DSM program, but that are not reimbursed by the utility. The nonutility expenditures should include only those additional costs necessary to purchase or install an efficient measure relative to a less efficient one.

Total Utility Costs: Refers to the sum of the total Direct and Indirect Utility Costs for the year. Utility costs should reflect the total cash expenditures for the year, reported in nominal dollars, that flowed out to support DSM programs. They should be reported in the year they are incurred, regardless of when the actual effects occur.

TOU: see Time-of Day (Time-of-Use) Pricing

Tower, Dead-End: A heavy tower designed for use where the transmission line loads the tower primarily in tension (pull in one direction) rather than compression (downward push); for example, in turning large angles along a line or bringing a line into a substation.

Tower, Suspension: Tower designed to support conductors strung along a virtually straight line with only small turning or descending or ascending angles. Approximately five suspension towers are used to a mile.

Transformer: A device for transferring energy from one circuit to another in an alternating-current system. It consists of a winding with a tap or taps, or two or more magnetically coupled windings. Its most frequent use in power systems is for changing voltage levels. The winding where energy enters is called the primary winding and the one or more energy-exit windings in the secondary(ies).

Transformer, Dry Type: A transformer that operates without oil as a cooling medium and is designed with insulation to withstand high temperatures.

Transformer, Instrument: A transformer that transfers primary current, voltage, or phase values to the secondary circuit with sufficient accuracy to permit connecting an instrument to the secondary rather than the primary; used to ensure that only low currents or low voltages are brought to the instrument.

Transformer, Line: A transformer classified as distribution line equipment, generally having a rated primary voltage of 2,300 to 15,000 volts. Such transformers usually are step-down transformers and either pole-type or underground.

Transformer, Phase-Shifting (Phase Shifter): A transformer which changes the power system phase angle to alter the pattern of flow to control inadvertant loop flow.

Transformer, Power: A transformer used to change the voltage level for power transmission and distribution. When a transformer is used to increase voltage for transmission, it is called a “step-up” transformer, and when used to lower voltages it is called a “step-down” transformer.

Transient: A momentary change or imbalance in an electric or control system.

Transmission: The movement or transfer of electric energy over an interconnected group of lines and associated equipment between points of supply and points at which it is transformed for delivery to consumers, or is delivered to other electric systems. Transmission is considered to end when the energy is transformed for distribution to the consumer.

Transmission Congestion: The condition that exists when electricity market participants seek to dispatch in a pattern which would result in power flows that cannot be physically accommodated by the system. Although the system will not normally be operated in an overloaded condition, it may be described as congested based on requested/desired schedules.

Transmission Grid (Power Grid): An interconnected system of electric transmission lines and associated equipment for movement or transfer of electrical energy in bulk between points of supply and points of demand.

Transmission Owner: An entity owning transmission facilities or having contractual rights to use transmission facilities that are used to transmit and distribute power from suppliers to end-use customers or distribution utilities.

Transmission Service: See Wheeling.

Transmission System (Electric): An interconnected group of electric transmission lines and associated equipment for moving or transferring electric energy in bulk between points of supply and points at which it is transformed for delivery over the distribution system lines to consumers, or is delivered to other electric systems.

Trip: The opening of a power circuit breaker by protective relays.

TRM: Transmission Reserve Margin

TSIN: Transmission System Information Network, same as OASIS

Turbine: A machine for generating rotary mechanical power from the energy of a stream of fluid (such as water, steam, or hot gas). Turbines convert the kinetic energy of fluids to mechanical energy through the principles of impulse and reaction, or a mixture of the two.

Turbine-Generator: A rotary type unit consisting of a turbine and an electric generator. Also called Turbo-Generator.

Turbine (Hydraulic): An enclosed rotary type of prime mover in which mechanical energy is produced by the force of water directed against blades fastened on a vertical or horizontal shaft.

Turbine (Steam or Gas): An enclosed rotary type of prime mover in which heat energy in steam or gas is converted into mechanical energy by the force of a high velocity flow of steam or gases directed against successive rows of radial blades fastened to a central shaft.

TWG: Technical Work Group

Two-Rate Watthour Meter: A watthour meter with two registers or sets of dials, constructed so that the off-peak energy will be recorded on one set of dials and the on-peak energy on the other set. The control of the recording system is by an internal time switch or external remote control signal. In the event of a power failure, carry-over for an internal time switch can be accomplished by battery or spring storage.

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Unbundled Rates: Separate line-item charges for generation, transmission, distribution, ancilliary services, and other services and programs.

Uniform System of Accounts: Prescribed financial rules and regulations established by the Federal Energy Regulatory Commission for utilities subject to its jurisdiction under the authority granted by the Federal Power Act.

Unit Commitment: The process of determining which generators will be brought on-line to meet load and provide ancillary services for the next scheduling period. Typically, generators with lower costs of production, or lower emissions are scheduled before higher cost and emissions generators.

Unit of Property: An assemblage of equipment consisting of individual items usually considered as a whole for determining the accounting treatment for replacement of that equipment.

Unplanned Outages: Outages of generation, transmission, or distribution facilities not planned in advance.

UPS: Uninterruptible Power Supply

USBR: United States Bureau of Reclamation

Useful Thermal Output: The thermal energy made available for use in any industrial or commercial process, or used in any heating or cooling application, i.e., total thermal energy made available for processes and applications other than electrical generation.

USGS: United States Geological Survey

USFWS: United States Fish and Wildlife Service

Utility Distribution Company (UDC): A distribution wires business and a regulated retailer who serves end-use customers.

Utility-Earned Incentives: Costs in the form of incentives paid to the utility for achievement in consumer participation in DSM programs. These financial incentives are intended to influence the utility's consideration of DSM as a resource option by addressing cost recovery, lost revenue, and profitability.

Utility Plant: All equipment used for the generation, transmission, and distribution of electricity, or an account in which record is kept of this equipment. Includes Plant in Service, Purchased or Sold, In Process of Reclassification, Leased to Others, Held for Future Use, and Under Construction, and Acquisition Adjustments and Adjustment Accounts, without deduction of Accumulated Provision for Depreciation and Amortization.

Utility Plant in Service: That portion of a utility's plant which is devoted to the operations of the company. Excludes plant purchased or sold, in process of reclassification, leased to others, held for future use, and under construction, and acquisition adjustments and adjustment accounts, without deduction of Accumulated Provision for Depreciation and Amortization.

Utility Rate Structure: A utility's approved schedules of charges for billing utility service rendered to various classes of its customers.

Utilization Factor: The ratio of the maximum demand of a system, or part of a system, to the installed capacity of the system, or part of the system, under consideration. Similar terms are Capacity Factor and Load Factor.

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Value, At-Site: The value of power at the site of the generating station as measured by the at-market value minus the cost of transmission facilities and losses from generating station to market. The amount of power at the site is more than the amount of power at the market due to transmission losses.

Value, At Market: The value of power at the market as measured by the cost of producing and delivering equivalent alternative power to the market.

Value, Capacity: That part of the at-site or at-market value of electric power which is assigned to capacity or capability.

Value, Energy: That part of the at-site or at-market value of electric power which is assigned to energy.

Value, Fuel Replacement: The value of electric energy, usually hydro, which may be substituted for energy generated in a fuel-electric plant, in terms of the incremental cost of producing the energy in the fuel-electric plant.

VAR: A unit of Reactive Power. For a two-wire circuit, the product of voltage times the current times the sine of the angular phase difference by which the voltage leads or lags the current. Vars and watts combine in quadrature relationship to form volt-amperes.

Vibration Dampener: A device put on transmission lines to dampen vibration and galloping conductors produced by wind.

Volt (V): The unit of voltage or potential difference. It is the electromotive force which, if steadily applied to a circuit having a resistance of one Ohm, will produce a current of one Ampere.

Voltage of a Circuit: The electric pressure of a circuit in an electric system measured in volts. It is generally a nominal rating based on the maximum normal effective difference of potential between any two conductors of a circuit.

Voltage Reduction: Any intentional reduction of system voltage by 3 percent or greater for reasons of maintaining the continuity of service of the bulk electric power supply system.

Voltage Regulator: An electric device that regulates voltage flowing through distribution lines. It automatically raises and lowers the voltage to maintain required voltage levels for service.

Voltampere: The basic unit of apparent power. The voltamperes of an electric circuit are the mathematical product of the volts and amperes of the circuit. The practical unit of apparent power is Kilovoltamperes (kVA), which is 1000 voltamperes.

Voltmeter: A meter that reads the potential difference that caused the current to flow in a circuit.

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WACM: Western Area Colorado Missouri control area, operated by the RMR.

WALC: Western Area Lower Colorado control area, operated by the DSWR.

Water Heating: Energy efficiency program promotion to increase efficiency in water heating, including distributing low-flow showerheads and water heater insulation wraps. Could be applicable to residential, commercial, or industrial consumer sectors.

Water Wheel: Any wheel designed to be rotated by the direct impact or reaction force of water. In a hydroelectric generator, the water wheel is sometimes referred to as the turbine.

Watt (W): The electrical unit of power or rate of doing work. The rate of energy transfer equivalent to one Ampere flowing under a pressure of one Volt at unity Power Factor. It is analogous to horsepower or foot-pounds per minute of mechanical power. One horsepower is equivalent to approximately 746 watts. A kilowatt=1,000 watts; a megawatt=1,000,000 watts.

Watt-hour (Wh): An electrical energy unit of measure equal to one watt of power supplied to, or taken from, an electric circuit steadily for one hour. A 100-watt light bulb will use 100-watt hours of electricity every hour it is in use. Retail electric energy is commonly sold by the Kilowatthour, while wholesale energy transactions commonly use Megawatthours or Gigawatthours.

Wave Trap: A device used in carrier current application to confine the carrier signal to one line. It is a parallel-circuit tuned to the frequency of the carrier signal.

Weir: A dam placed across a river or canal to raise or divert the water, as for an irrigation diversion, or to regulate or measure the flow.

Western:See Western Area Power Administration

Western Area Power Administration (WAPA): An agency within the Department of Energy responsible for marketing power.

Western Electricity Coordinating Council (WECC): One of nine Regional Reliability Councils of NERC that covers 14 Western States, two Canadian provinces, and portions of northern Mexico. WECC is subdivided into four areas, namely: Northwest Power Pool Area, Rocky Mountain Power Area, Arizona-New Mexico Power Area, and the California-Southern Nevada Power Area.

Wheeling: The use of the transmission facilities of one system to transmit power of and for another system. As applied to WAPA, the transmission of large blocks of electric power of the WAPA system from non-Federal hydro and/or thermal generating plants to points of use by utilities owning or purchasing the output of such plants. Wheeling service contracts can be established between two or more systems.

Wheeling Charge: The amount paid to an intervening system for the use of its transmission facilities.

Wheeling-Out: An energy transaction originating within and flowing through a power system operator's transmission grid to a destination outside of the power system operator's transmission grid.

Wheeling-Through: An energy transaction flowing through a power system operator's transmission grid whose origination and destination is outside of the a power system operator's transmission grid. Also referred to as a Through-Schedule.

Wheeling Service: See Wheeling. Also referred to as Transmission Service.

Wholesale Sales: Energy supplied to other electric utilities, cooperatives, municipals, and Federal and State electric agencies for resale to ultimate consumers.

Wicket Gates: Vertical valve-shaped gates which control the flow of water to the turbine runner.

Wind Power: Energy extracted from the wind used to generate electricity. The energy available in the wind is a function of the cube of the wind speed. Doubling the wind speed increases the power available by a factor of 8. The wind power equation is W=½ r A v³, where W is wind power, r is air density, A is rotor area, and v is wind speed.

Wind Turbine Generator: A generator powered by a turbine driven by the wind.

Winter Season: Designated months for delivery of capacity and/or energy, those months being: CRSP MC and RMR use October through March; UGP uses November through April; and Parker Davis (DSWR) uses October through February.

Winter Peak: The greatest load on an electric system during any prescribed demand interval in the winter or heating season, usually between December 1 of a calendar year and March 31 of the next calendar year.

Withdrawable Capacity: Power that is reserved for some other use, such as project-use load, but is not currently being used. When the primary dedicated user needs the power, it may be withdrawn from current customers.

WRP: Western Replacement Power. A replacement option under the SLCA/IP firm electric service contract. WRP may be purchased as Seasonal WRP, Long-Term WRP, or for shorter time periods.

WRTA: Western Regional Transmission Association. WRTA merged with WSCC and SWRTA to create WECC.

WSCC: Western Systems Coordinating Council, now known as the WECC, Western Electricity Coordinating Council .

WSPP: Western System Power Pool

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YTD: Year to date


Updated: June 25, 2008