Electricity generation is being reduced for 12 hours a day at a second Victorian power station due to industrial disputes between the workforce and the station's owners.
The Loy Yang B coal power station in the Latrobe Valley has been generating 20 per cent less than full capacity between 7am and 7pm since early February, according to Trevor Rowe, a spokesman for GDF Suez, the company that owns Loy Yang B.
But the industrial action at Loy Yang B and Yallourn power stations was not affecting electricity supplies, an Australian Energy Market Operator spokeswoman said.
Mr Rowe said: "Unions are continuing to impose bans limiting electricity generation at Loy Yang B power station, despite delaying talks on a new enterprise agreement that would deliver annual pay increases of 5 per cent, as well as increased annual leave and improved superannuation benefits."
Union members started reducing generation at Loy Yang by 20 per cent for four hours a day in January then increased it to 12 hours a day around February 6.
Mr Rowe said the existing enterprise bargaining agreement expired in September 2012 and negotiations for a new agreement began last July.
"The company hopes to reach an agreement as soon as possible and has sought assistance from the Fair Work Commission several times to help resolve the dispute," he said.
CFMEU spokesman Greg Hardy was in negotiations at Yallourn on Tuesday and could not be reached for comment.
Meanwhile, the owner of Yallourn power station, EnergyAustralia, has applied to the Supreme Court of Victoria for orders restraining its staff from reducing output. Justice Elizabeth Hollingworth is expected to deliver her decision on Wednesday.
CFMEU members have been using a manual override to reduce output at four Yallourn generators between 4pm and 6pm every afternoon since March 1, cutting output by up to 38 per cent.
The action was also a protest against enterprise agreement negotiations. The Fair Work Commission deems both protected action.
The energy market spokeswoman said the industrial action would not cause brownouts or affect its ability to meet demand, even as the industrial action has coincided with a heatwave. But if both stations were shut down completely, this could put the state in a vulnerable position.
Yallourn and Loy Yang account for 23 per cent of Victoria's generation capacity.