by Shane Capron
Load growth in the Cheyenne, Wyo., area of the Rocky Mountain region means constant upgrading and installation of some big equipment. In November 2013, the region installed a new 230/115-kilovolt transformer, called KV2A, in the Cheyenne Substation to help provide reliability in the area.
“Load growth in the Cheyenne area has required us to do a lot of work,” said RM Construction Project Manager Travis Anderson. “Not only are we installing this transformer, but we’re working with our other partners such as Cheyenne Light, Fuel and Power to upgrade the system in many locations.” Due to load growth at the Cheyenne Substation, Western planned for the additional transformer, which served as Phase 2 of the project. The transformer installation concludes the project, though the substation was designed to accommodate additional growth if necessary.
RM Electrical Engineer Kurt Vogel, who inspected the installation, was there to see transformer KV2A installed at the substation and has seen a dozen or so transformers installed during his time with Western. Vogel said “They had to bring the transformer in on a railroad car and then drive it over to the substation on a special truck, closing down streets in Cheyenne.” He continued, “Then, at the substation, they had to modify the truck to get it in through the gates.” But that was just the beginning.
Picture a 325,000-pound transformer sitting on a rail car. How might you safely get it to the substation and nestled onto the cement pad? First, it takes a 600-ton crane. But you might wonder what it takes to bring in and assemble a 600-ton crane? That would be the 110-ton crane.
Heavy lifting, expert oversight get job done
The well-orchestrated event took the construction contractor three days, including set up and tear down. After waiting a few extra days for the train to arrive, the 600-ton crane was moved to the rail yard where they assembled the “big” crane using the “little” crane, then moved the transformer onto the truck for the drive through Cheyenne to the substation. While the truck was winding its way through town, the little crane took apart the big crane and was then moved to the substation to repeat the process. Once set up in the substation, Vogel said, “The actual work of lifting the transformer onto the pad took only 5 minutes.”
Vogel was there to make sure that it was correctly moved and gently set down with no cracks or other damage, all before Western wrote the final check for this big-ticket item. Safety and quality control are Vogel’s responsibility as the lead construction control representative. He normally wouldn’t be out in the field as much as he has been, but they have been so busy he needs to be out inspecting field operations. Generally, new substations and additions are built by contractors; Western doesn’t have resources to spend six months building a substation.
This complex process is expertly overseen by Western crews, says Anderson. “The construction contractor does the heavy lifting, moving the big steel. Western staff go in and test everything and make sure relays and protective devices are doing the right thing, to make it all operational; and that is a big job.”
A lot of work will need to be done before the transformer is operational later this summer. The transformer comes bare when it is delivered to the pad. Vogel said, “Five semis come later with bushings and plumbing,” and the transformer gets fully installed, which is called “dressing the transformer out.” Western hired a contractor to do the work, and the manufacturer will send a representative out to oversee the “dressing,” which will likely require a specialist to drain and refill the oil in the transformer. Western will also add an additional breaker and three switches and will have to modify the bus that was separated to allow for installation.
This project was unique because the substation is composed of two yards: a lower 115-kV yard just down the hill from the newer 230-kV yard. Western will build a connecting power line from the lower yard to the upper yard to allow power to move across the two different voltage systems. Western will then be able to supply power to the new transformer from two directions, so if one side goes down, operators can still supply power from a different direction to maintain service and increase reliability. In the fast-growing Cheyenne area, projects like this one are critical to maintaining service and reliability for the future.