Arizona Public Service powers up new transformers one year after fire

MESA, ARIZONA - Three new transformers at the Westwing Substation in the northwest valley were energized as planned, bringing the Valley's electric system up to full capacity for the peak summer air conditioning season.

"It all went according to plan. It's rolling," said Jim McDonald, a spokesman for Arizona Public Service, which operates the substation.

The transformers were powered up exactly one year and two days after a fire at the substation damaged or destroyed five of the switch yard's 14 transformers and touched off an electric supply crisis in the Valley that lasted through end of last summer.

Utilities were forced to call for voluntary conservation by consumers during the hottest part of the year as they scrambled to develop other ways of getting more power to the Valley.

With the revamping of Westwing, which is located at Happy Valley Road and Loop 303 in Peoria, the Valley has an adequate capacity cushion to get through this summer, even with population growth and consumers cranking up their air conditioners to stay cool, utility officials said.

"As we went into this summer we felt confident in our ability to insure reliability even before the repairs," said APS spokesman Damon Gross. "However, these repairs give us even more redundancy as we head into the peak period."

So far this summer the peak use of electricity occurred on June 21 at 10,120 megawatts. Prior to Wednesday, the Valley's electric system, including facilities systems operated by APS and Salt River Project, had a capacity of 11,390 megawatts. The installation of the new transformers brings that up to 12,100 megawatts, according to APS figures. A megawatt is a measure of electricity demand. One megawatt is enough energy to power about 250 average-sized homes in the Valley, Gross said.

Immediately after last year's fire APS began the Westwing repairs by purchasing a transformer from the Bonneville Power Administration in the Pacific Northwest, which filled the gap by early August. But four others remained out of service.

APS ordered seven new transformers from ABB in Montreal, five to replace the ones that were damaged and two replacements for transformers that are still in operating condition but are three decades old.

The first ABB transformer went into service June 2, replacing the Bonneville transformer, which now is being used as a spare. The next three replacements arrived in June, and they were turned on Wednesday after several weeks of testing.

The final three replacements will arrive before the end of this year. They will make the substation more efficient but will not increase its capacity, Gross said.

The improvements, which include the installation of fire protection walls and fuel pits to confine any future blazes, are costing a total of $37.2million, of which about $26.5million is covered by insurance, he said. The uninsured portion is being split among APS, Salt River Project and the Western Area Power Administration, an agency of the federal government.