Public Enterprises Minister Lynne Brown used the platform provided by the State of the Nation Address debate on Wednesday to announce that the turbine at Medupi Unit 6 was "running at the optimum speed of 3 000 revolutions per minute", which represented a "critical milestone" in the commissioning of the unit.

But she also confirmed that grid synchronisation of the 794 MW unit, which was initially expected by December 24 and then by the end of February, had been delayed "for more than six weeks".

She said the delay had arisen after Eskom "embarked on a cautious route to ensure that all systems were in place before synchronisation of the unit".

The 4 764 MW coal-fired station, which is being built in South Africa's Limpopo province, is about three years behind schedule and well over budget, having been plagued by labour strife and funding difficulties.

Eskom is also yet to provide a final cost estimate for the project and has also not provided a firm update regarding the expected interval between units – the final plant will comprise six units.

It recently reported that Kusile Unit 1, which is being built simultaneously in Mpumalanga, is scheduled for synchronisation only in the first half of 2017, with that 800 MW unit expected to enter commercial operations during the second half of 2017. This, too, represents a major schedule slippage from earlier indications that synchronisation could be achieved in the first half of 2016.

Brown also announced that the long-delayed procurement process to replace the boiler at Duvha Unit 3, which failed catastrophically last year, was finally under way.

In addition, she said that "permanent repairs" were under way at the Majuba power station, where Eskom had created a temporary solution following a coal-silo collapse in November last year, which precipitated the most recent round of load shedding.

"Majuba is now able to provide full power at the morning and evening peaks and an average of 85% power during the day," the Minister said.