Fires broke out at a power plant in Queens for a second day in a row early Wednesday, temporarily disrupting some power supplies in New York City as residents cranked up air conditioners in near record numbers during one of the hottest weeks of the summer.

The fire damaged a transformer at NRG Energy's 614 megawatt Astoria gas turbines, blocking about 140 MW of generating capacity from getting to the city's power grid, Lesa Bader, a spokeswoman at NRG said.

Bader said the fire started at about 4:30 a.m. Eastern time and was contained by the New York City Fire Department by about 7:00 a.m. She noted the fire caused no injuries.

NRG, a subsidiary of Minneapolis-based energy giant Xcel Energy Inc. , is now looking for a replacement transformer to make the plant fully operational again, a process that could take many months.

Electricity demand typically peaks during the summer, when air conditioning accounts for about a third of all power used.

The mercury rose to the mid-90s degrees Fahrenheit on Monday and Tuesday, while the heat index, which combines the effect of the heat and humidity, made it feel more like 105 degrees F.

For the rest of the week, meteorologists forecast high temperatures in the low to mid-90s F and a heat index reaching 104 degrees F on Thursday.

THE RELIANT FIRE

Late Monday, there was another fire at the Astoria plant in a transformer owned by Reliant Resources Inc. , which is majority owned by Houston-based energy giant Reliant Energy Inc. .

Officials said the fires on Monday and Wednesday were not related.

The fire on Monday caused the 1,254 MW Astoria plant to shut, knocking out power for nearly 9,000 customers in Consolidated Edison Inc.'s distribution system for a few hours.

By Tuesday evening, Reliant Resources had all four of its Astoria units back on line.

Richard Wheatley, a spokesman for Reliant Resources, told Reuters Wednesday morning the fire at the NRG side of the plant caused one of Reliant Resources units to trip off line again.

Wheatley said Reliant Resources was working on returning that unit to service again this morning.

There are three parts to the Astoria plant, the biggest power station in New York City.

Reliant Resources owns the four unit, 1,254 MW natural gas/oil-fired power station.

NRG owns the Astoria Gas Turbines facility, which consists of 19 generating units, 12 of which are dual-fuel gas turbines using natural gas as a primary fuel source and kerosene as the back-up fuel, capable of generating 480 MW. The other seven are kerosene-fueled industrial combustion turbines, capable of generating 145 MW.

The New York Power Authority owns the 825 MW oil/natural gas-fired Poletti station, which is physically attached to the plant owned by Reliant Resources.

Con Edison, which sold the Astoria facilities to NRG and Reliant Resources in 1999 as part of the deregulation of the wholesale electricity market in New York, distributes power, natural gas and steam to more than 3 million customers in the metropolitan area.