Callide’s B1 generator unit tripped this morning during maintenance. The B2 unit tripped on Tuesday when there was a hot gas exceedance and it won’t return to service until next week. The C3 unit had a water tower structural failure on Monday.

Callide’s C4 unit has also been offline and not due to return to service until April next year after a fire in May 2021.

It followed a ransomware attack on CS Energy in December and came as the Kogan Creek and one of the Gladstone generators were also offline because of routine maintenance that was usually scheduled for this time of year when demand is not normally very high.

CS Energy chief executive Andrew Bills said he was “not at all happy with the performance of our plant”, but said there was no cause for concern about electricity supply.

The Australian Energy Market Operator and Energy Minister Mick de Brenni backed up that statement saying there had not been any lack of reserve notice after this morning’s incident.

“In fact, Queensland is blessed with an abundance of diverse energy supply. There are no concerns going forward about the security of supply,” Bills said.

“It’s a distinct series of coincident events. What happened this morning was normal operating practice, but it happened on top of what had occurred earlier in the week.

“The generator testing is something we have to do. Unfortunately, we had an exceedence, we need to understand why and that’s why we do the testing. What happened on Monday, we were guided by three experts on what we should be doing and how we should be maintaining it.”

Bills said the B1 is back on line and B2 will be back next week so the claims that there was a risk of blackouts “were slightly misleading”.

The replacement for the C4 unit has landed at Fisherman’s Wharf and would soon start a five day journey to the site.

Mining and Energy Union Queensland vice president Shane Brunker said the outages at the plant proved maintenance was being neglected “in the race to shut down coal power and move to renewables”.

He called for the Government to step in to ensure the responsible management and maintenance of the facility, which was commissioned in 2001 and is one of Australia’s newest coal-fired generators.

“The focus should be on investing in the existing fleet and exploring opportunities to improve them rather than running them down,” Brunker said.

The union said most of Queensland’s major generators were operating at reduced capacity this week.

The union warned there could be loadshedding and power outages in Queensland if the temperature rises, increasing electricity demand, or if wet weather knocks out solar generation capacity.

Premier Annastacia Palaszczuk insisted Queenslanders would have enough electricity to get through the weekend, and said cabinet would be updated on the situation on Monday.

“I’m advised that we have enough supply in the system at this stage – we’ll be getting that update on Monday,” she told reporters.

The Premier denied maintenance was being neglected at state-run plants, saying “these outages happen from time to time”.

_ Additional reporting AAP