Calif PG&E Helms 2 hydro unit offline, planned work

LOS ANGELES, July 6 (Reuters) - The 404-megawatt Unit 2 at the PG&E Corp (PCG.N) Helms Pumped Storage hydropower station went offline for planned work on Monday, the California Independent System Operator said in a report.

The other two units, also of 404-MW capacity, at the plant remained available for generation.

There was no indication how long Unit 2 would be out of service for maintenance work.

The 1,212 MW Helms station, which entered service in 1984, is located near Fresno in Fresno County. There are three 404 MW Units 1-3 at the station.

One MW powers about 700 homes in the PG&E coverage area in California. Pumped storage plants store and produce electricity to supply peak power demands by moving water between reservoirs at different elevations.

PG&E's regulated Pacific Gas and Electric Co subsidiary owns and operates the station. (Reporting by Bernie Woodall; Editing Bernard Orr)