A major central Queensland power station is completely offline after multiple equipment failures.
CS Energy said all four units at the coal-fired Callide Power Station in Biloela were not operating.
On Monday a structural failure at the cooling plant brought the C3 unit offline, while on Tuesday afternoon the B2 unit tripped during scheduled testing.
CS Energy chief executive Andrew Bills said the final operating unit, B1 also tripped this morning.
"I'm not at all happy with what's occurred," he said.
"I'm incredibly disappointed and I want to reiterate that our commitment is making sure that we provide Queenslanders that secure reliable energy that they've always had.
"To be in that position is incredibly disappointing.
"It's not good enough and we're doing what we can to get that back online."
Mr Bills said the B1 unit came offline because a safety protection system detected a vibration on a heat pump.
"That's kind of what I would consider normal operating practice, it's just bad timing in terms of the other things that have occurred at Callide," he said.
Mr Bills said the B1 unit was expected to come back online at 4pm today, while each of the other units remained offline for different reasons.
He said he had spoken to Powerlink and the Australian Energy Market Operator (AEMO), who said there was enough supply in the system to manage demand until the B1 and B2 units returned to service.
The coal-fired station is made up of two power stations, Callide B and C, with each power station having two generating units which supply baseload electricity to the national grid.
CS Energy, the state-owned company, owns 100 per cent of Callide B and is in a joint venture with InterGen for Callide C.
The incidents come less than two years after an explosion at the station's C4 unit during a catastrophic incident resulted in power outages for 470,000 homes and businesses across Queensland.
The C4 unit remains offline while it is being rebuilt.
Three incidents in one week
CS Energy said the B2 unit also tripped on Tuesday while doing scheduled, four-yearly testing required by the market operator.
"During that testing there was a release of high temperature gas which damaged some of the cables which are currently being replaced," Mr Bills said.
"I am concerned that it has occurred … it shouldn't have occurred.
"We're replacing those cables and really drilling into exactly what contributed to that."
CS Energy said in addition to the unit's automated control system response, the onsite team acted quickly to make the unit safe.
It said no one was injured and an investigation into the incident was being completed, while the unit was due to return to service on November 9.
On Monday a "structural failure" resulted in part of the C3 unit's cooling plant collapse.
At the time, CS Energy said nobody was injured.
Mr Bills said CS Energy has provided guidance to the market that the C3 unit wouldn't operate until January 3.
He said the wooden cooling structure was part of a $7 million upgrade project planned for January to address known issues.
"That program was in place but unfortunately, we didn't get to January," he said.
Queensland Energy Minister Mick De Brenni said the state's power system was secure, with supply currently exceeding available demand.
Concerns raised
The Mining and Energy Union's Shane Brunker said the incidents confirmed the union's concerns the state's suite of coal fired power facilities were not being properly maintained.
He met with workers in Biloela last night to go over Monday's C3 unit and Tuesday's B2 unit incidents.
"It's of great concern to us, the union and the workers, [there's] a lot of frustration," Mr Brunker said.
"They've lost confidence in the management of the power station."
Mr Bills said the power station's maintenance plan worked with its asset plan, in accordance with statutory requirements.
"We absolutely follow that through to the letter," he said.
Mr Bills said he was at the power station last night meeting with workers and unions.
"[I was] … making sure everyone's getting the support they need in terms of bringing these units safely and very methodically back online, and also that our people are getting the support they need in that process," he said.
"We've got to work together and make sure that people, those concerns are heard and understood.
"We're working together to address them and that's exactly what I'm committed to."
