Transformer changeout involves meticulous planning and flawless execution
By Geoff Oldfather
It’s not easy to move a transformer. For starters, there is the sheer size and weight of it.
“This transformer weighs 153,000 pounds dry, not dressed out or anything yet,” says Dominic Rydzak, substation apparatus technician.
Dominic was on hand as heavy lifting began on a transformer replacement the week of November 17 at Bicknell Substation.
“The big challenge in moving it is preventing it from coming off the trailer because it’s top heavy, so that’s a lot of weight to be traversing through the gravel and everything else,” Dominic says. “This has to be done precisely right. Everything has to be level, every move has to be done carefully, because if it’s not you run the risk of it falling over.
“We did the process called ‘jack and roll,’ where we jack the transformer off one trailer, then move it to another trailer in order to move it to the pad (inside the substation). It is chained down while it’s being moved. It’s the same process in to put it in place: jacking it up, pulling the trailer out from under it, then jacking it all back down on to the concrete pad. It takes a while.”
Dominic and his crew enjoy the challenge and showing off their expertise.
“It’s a lot of fun,” he says. “It’s not something we do every day.”
It took several years of planning, engineering, logistics, and preparation before removing a 40-year-old transformer replacing it with a new, state-of-the-art transformer.
With the new transformer safely in place, the engineer in charge of the project reflected on the exhaustive work involved.
“It’s been challenging simply because it’s a remote location and it’s a large transformer for us in what I would call a congested substation,” says Claudia Aster, AzGT electrical engineer. “The substation has all levels of voltage and it’s pretty tightly packed for equipment.”
The new 345-kilovolt to 230-kilovolt step-down transformer is in what is called a “hub” because of all the ties and the large power loads it serves.
Bicknell Substation allows for interconnection with neighboring utilities, including Tucson Electric Power and Trico Electric Cooperative. TEP’s Vail Substation comes into Bicknell. It allows power to flow back and forth, giving voltage support to and from TEP.
“It’s a critical tie for us,” Claudia says. “We have a Trico yard in the Bicknell Substation that goes out and serves Green Valley and a couple of the mines there. It also has lines coming out to Three Points, which is another Trico substation.”
With the transformer came the need for a new breaker. Fitting that breaker in the small area on the north side of the transformer also was a challenge.
Now that it is in, Claudia says the benefits project far into the future.
“This gives us something we can replacing was getting old, and we would rather do it proactively than have it go down and wait for a year for a new transformer. It’s going to greatly enhance reliability.”
The new transformer also enhances substation capacity since it is almost double the size. This supports growth and future demand for power.
Seeing the project come to fruition is satisfying for Claudia.
She credits Magaly Osorio for electrical design on the substation. Kathy Moreno coordinated the project with the support of Dustin Teague, who put together the yard and the connectors.
“I couldn’t do this without the help of my co-workers,” she says. “I enjoy coming to work and dealing with all the issues to make it happen, so to see it come together, that’s the best part.”