By Philip Reed
In January, construction began at Lingle Substation in Goshen County, Wyoming. The work continued through May. It was a job involving a local construction contractor, several upgrades and structural replacements, all of which stemmed from one unwelcome visitor:
the turkey vulture.
“There had been several extended station outages due to turkey vultures breaking the minimum approach distance and causing faults on the main bus," said Electrical Engineer Brian Bucks.
This was obviously bad news for the turkey vultures as well as WAPA's customers.
“When faults occurred due to the turkey vultures, the old post insulators were usually damaged," Bucks continued. “These old insulators are a challenge to find replacements for."
“We had several customer outages in the Lingle area and to the west," confirmed Field Maintenance Manager William Weber. “These were all caused by wildlife getting into places they should not have been."
The main work at Lingle, Weber explained, consisted of moving the 34.5-kilovolt bus and switches so that they would be farther apart, preventing the outages turkey vultures and other critters could cause.
Doing this also presented an opportunity to make other improvements, however.
“We wanted to replace all of the oil breakers in the sub with SF6 gas breakers," Weber continued. “This substation sits very close to the Platte River as well as other small bodies of water."
Additionally, the insulators were replaced, which would mitigate the outages caused by wildlife and thereby improve reliability.
“We could see where they were contacted by turkey vultures," said Bucks. “We could see the arc marks on the copper bus-work as well."
Bucks went on to explain that the existing 115-kV brown post insulators were nearing the end of their lives.
“We replaced those with new Epoxilator station post insulators on May 14," Weber said. “Some of the brown glass had cracks and may well have separated soon. This was a good chance to replace them before they caused any further problems down the line."
“We were also able to remove oil-filled equipment from a Spill Prevention, Control, and Countermeasure site," Bucks continued.
Lingle Substation is located near a decommissioned Bureau of Reclamation powerplant that dates back to the 1920s and was originally tied to that facility. As a result, the original foundations had degraded and a number of the structures – built through the 1930s and 1940s – were reworked and replaced as part of the upgrades. This includes the entire structure for the 34.5-kV breakers.
On May 19, a number of the craft employees who worked on the project came together at the substation for a construction closeout site visit. This included Foreman II Electrician Dale Beaudette, Supervisory Civil Engineer Scott Esplin, Civil Engineer Adam Haun, Engineering and Construction Manager Mike Korhonen and the contractor, who provided a one-year warranty on the company's workmanship.
“It was a big job, and it might seem silly that all of this came from a problem with turkey vultures, but nothing is silly when it comes to reliability for the customers who depend on this substation," said Weber. “It's a good feeling when you're not only keeping the power reliable, but making it more reliable."
SF6 breakers vs. oil breakers
Sulfur hexafluoride circuit breakers use sulfur hexafluoride gas to cool and quench the arc on opening a circuit. Initially developed in the 1950s, SF6 breakers are used in electrical grids at transmission voltages up to 800 kilovolts as generator circuit breakers, and in distribution systems at voltages up to 35 kV. Advantages over other media include lower noise, no emission of hot gases and relatively low maintenance needs.
Oil-filled breakers contain mineral oil which, if discharged during a failure, will pose a fire hazard. Oil is also toxic to water systems and leakages must be carefully contained. SF6 breakers avoid these potential issues.
Lingle Substation faced a potential threat to its reliability
in the form of the turkey vulture. Ultimately, the upgrades
made as a result benefit both the customers and
the birds. (Photo by Brian Bucks)
What is a turkey vulture?
Common name: turkey vulture
Scientific name: Cathartes aura
Size: 27" length, 69" wingspan
The most widespread vulture in North America, the turkey vulture is often called a buzzard. A turkey vulture standing on the ground can, at a distance, resemble a wild turkey. It is unique among North American vultures in that it finds carrion by smell as well as by sight. When threatened, it defends itself by vomiting powerful stomach acids.
Source: National Geographic