UPDATE 3-Fire damages Con Ed transformer in Dunwoodie, NY

(Updates with company comments)

NEW YORK, Nov 4 (Reuters) - A fire consumed a 345-kilovolt power transformer at Consolidated Edison Inc's (ED.N) Dunwoodie substation in Yonkers, New York early Wednesday morning, a company spokesman said.

He said the fire affected only one of the station's many transformers and did not cause any injuries or cut off service to any customers.

The company expected to replace the transformer over the next several weeks, "certainly before the end of the year," the spokesman said, noting the timing depended on how much work needed to be done to prepare the site for the new transformer.

Con Edison said it did not have a transformer at Dunwoodie but had one at a storage facility in Queens, New York. Electricity traders guessed it would take seven to ten days to replace the transformer once it was at Dunwoodie.

The spokesman said demand for power was currently low compared to the peak summer air conditioning season so the loss of the transformer now would not affect customer service.

Traders noted Dunwoodie is a major substation that transports power form Upstate New York, including the Indian Point nuclear power plant, to New York City, Westchester and Long Island.

With many redundant systems at the substation, the spokesman said the company was able to continue to moving power through the station despite the fire.

The traders noted that soon after the fire started at about 5 a.m. Eastern time, NRG Energy Inc (NRG.N) starting generating a few hundred megawatts of power at its 550-megawatt Astoria gas turbines in Queens.

Although Con Edison continued to move power through Dunwoodie, the traders guessed the state grid operator dispatched the Astoria gas turbines to serve as a backup or to generate power no longer flowing through the damaged transformer.

The fire was under control by about 8:45 a.m. on Wednesday, a Con Edison spokeswoman said.

Transformers use a type of non hazardous mineral oil for cooling. It was the mineral oil inside the transformer that burned, the spokesman said.

Con Edison, of New York, provides electric, gas and steam service to more than 3 million customers in New York City and Westchester County, New York. (Reporting by Scott DiSavino)