“Eskom technicians are in the process of performing start-up tests in an effort to bring back to service unit one of the Koeberg power station,” it said in a statement.
The unit, which produces 900MW, was taken off line on Sunday due to a technical fault.
Earlier on Monday Eskom said the power grid was under pressure as a result of the failure of the unit.
“Unit one is expected to be fully operational by the end of this week, which will increase capacity going into the weekend.”
However, acting chief executive Dan Marokane said the unit would be taken off line again next Monday for scheduled maintenance.
“The unit will still go out on a scheduled shutdown on Monday 9 February 2015, and is expected to return back to service at the end of May,” he said.
“The scheduled shutdown of Koeberg unit one is part of Eskom’s overall maintenance programme for its fleet of power stations.”
Unit two was operating at full power, producing 930MW for the grid.
Marokane urged the public to use power sparingly.
“We request sustained savings as we continue with our maintenance plan and efforts to balance demand and supply.”