General Electric Co. is buying privately held Lineage Power Holdings Inc. in a deal worth about $520 million so its energy unit can gain a foothold in the power conversion space.

The Fairfield, Conn. company said Thursday that the purchase from The Gores Group LLC is another step in its energy expansion efforts. In October GE said it planned to buy energy infrastructure company Dresser Inc. It also plans to make a buyout offer for oil pipe maker Wellstream Holdings PLC.

The Lineage Power acquisition is expected to close in the first quarter.

Lineage Power, based in Plano, Texas, had 2010 revenue of approximately $450 million. It has almost 2,300 employees and manufacturing operations in China, Mexico and India.