Kendal power station in Witbank tripped at peak evening demand last week, forcing Eskom to implement load shedding. The plant has begun operating again. Photo: Reuters

Johannesburg - South Africa plunged into darkness yet again yesterday when Eskom implemented another load-shedding schedule barely a week after the lights went off in some communities last week.

The utility started load shedding just after the close of business yesterday and it was expecting that this would last for about two hours.

Supply was “particularly constrained” and yesterday was “one of those days where if anything goes wrong, we might have to resort to load shedding”, the company said earlier in the day in response to queries.

A mismatch between supply and demand is forecast again for today and tomorrow, and Eskom urged people to put off the use of geysers, stoves and heaters until after 9pm.

The utility expected evening peak demand to reach 35 026 megawatts this evening and 35 192MW tomorrow.

When Eskom restored power to the areas affected by load shedding last week, it noted that the supply had been stable during the weekend only because of lower demand associated with the weekend peak periods.

Since the weekend, Eskom had been able to generate just under 34 000MW of electricity to meet peak demand during the evenings.

The state-owned utility said it was not the surge of demand to beyond 35 000MW that had created a problem because it had faced winter peak demand of beyond 36 000MW before and met it.

Eskom was concerned this time about the aged generating units, which often had boiler tube leaks and tripped more often when their maintenance was deferred.

Last week two units at the Duvha and Kendal power stations tripped at the evening peak and this was why the company had to implement load shedding.

While the Kendal unit returned to operation yesterday, Duvha had not.

Each unit of Eskom’s big power stations has the capacity to generate 600MW, and the tripping of one more would be detrimental to Eskom, whose unplanned outages stood at 5 600MW on Monday. - Business Report