What a total Eskom power blackout in South Africa would look like
During a media briefing on Tuesday, Eskom CEO André de Ruyter reminded South Africans what a total blackout of the electrical grid would mean.
The state-owned power utility announced a sudden increase to stage 4 load-shedding this morning after Majuba unit 5 and Tutuka unit 4 tripped.
Load-shedding is implemented as a last resort to protect South Africa’s grid from a total blackout, Eskom says.
De Ruyter explained that a total blackout happens when the frequency of South Africa’s alternating current supply gets too high or too low.
“The system operates at 50 hertz (Hz). You can regard this as the heartbeat of the system,” said De Ruyter.
“When that heartbeat goes too high or too low, then we have a significant risk to the system.”
He said bringing the grid back online if Eskom can’t maintain a stable frequency will take a week or longer.
The ramifications for South Africa’s economy would be disastrous — which is why Eskom resorts to load-shedding to prevent that from happening.
Chris Yelland, managing director of EE Business Intelligence
Energy expert and EE Business Intelligence managing director Chris Yelland previously explained that a total blackout could happen if Eskom allows power distribution hardware to become overloaded.
Safety features designed to protect the equipment against catastrophic failure would cause a cascading trip-out — unless they reduce electricity demand.
“When demand exceeds supply, what happens is you have overloading of generators, transformers, cables, and switch gear,” said Yelland.
Trips are installed to prevent massive damage in the event equipment is overloaded.
If there is an overload and equipment starts to trip, the overall electricity supply decreases, but the demand stays the same.
This places even greater strain on the parts of the grid that are still on, causing them to overload and trip if you do not act quickly — once again reducing supply.
Yelland said that if you had an aerial view of the country, you would see these cascading trip-outs spread as a wave of darkness sweeping the country.
Another way South Africa could be plunged into darkness is if Eskom’s national control centre operators take their eye off the ball.
This is according to mining and energy analyst Ted Blom.
He said these operators must be alert and competent when the grid is susceptible to outages.
If Eskom’s grid starts deviating too much from 50 Hz, and the control centre operators don’t catch it in time to bring it back into balance, Blom said it could cause a “meltdown”.
He said there were many examples of this happening in other countries, including the USA, India, and Pakistan.
Besides leaving the country without power, a national blackout would put Eskom in a position where it needed to bring power back online from scratch — a “black start”.
While De Ruyter said this could take “a week or longer”, Blom and Yelland agree it would likely be longer.
According to Yelland, 2–3 weeks is a more realistic estimate.
Yelland explained that power plants use some of the electricity they generate to run equipment like conveyor belts that feed coal into furnaces.
To start these up, you must begin with a small diesel generator to bootstrap the rest of the power plant.
The small generator generally starts up a larger generator, which is used to fire up the rest of the plant.
“There are procedures and protocols in place to do a black start. This matter has been carefully thought out and procedures put in place,” Yelland assured.
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