Line fault reduces output at Koeberg power station

What happened

On 20 January 2026 at 16:53, both units at Koeberg Nuclear Power Station were reduced from full power to 100 MW each after a fault on the 132 kV transmission lines supplied from the Pinotage transmission substation near Stellenbosch. Eskom described the reduction as an expected response to protect the power station and the national grid. It said the reactors were not affected and that the National Nuclear Regulator was informed. The National Transmission Company South Africa approved a return to higher output. Eskom said there was no risk of load shedding because national generation reserves were adequate.

Contributing factors

A fault on the 132 kV transmission lines supplied from the Pinotage transmission substation. The cause of that fault was not reported.

Lessons learned

1. A fault on transmission lines serving a large generator can require output to be reduced to protect the station and the wider grid.
2. Where a nuclear station is involved, confirm that the reactors were not affected and that the regulator has been informed.
3. Raising output again should wait for transmission approval and a check of available reserves, so that a line fault does not become a supply emergency.

Source

eskom.co.za