Why load-shedding in Johannesburg lasts 4 hours

Hanno Labuschagne

Hanno Labuschagne

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Why load-shedding in Johannesburg lasts 4 hours​

Johannesburg residents are among the only South Africans who experience four-and-a-half hours of load-shedding under stage 2, with most other South Africans only being subject to two-hour blackout periods.

Eskom recently rectified this for the areas of Johannesburg that it supplies, but City Power, which supplies power to the majority of built-up areas in Johannesburg, said its load-shedding schedule will remain unchanged.

This is because the nature of the electricity grid in Johannesburg makes it impossible to reduce load-shedding periods to two hours.
 
So because the areas are large they have be in the dark for longer? Wat? Wouldn't it make more sense that because the areas are large they only switch it off for 2 hours?
 
Perhaps if they had built more substations that fed off the main ones they could stop certain areas. Like my area alone has 3 sub stations that could cause issues for me.
 
I wonder why we don't have stuff blowing up in dbn with our 2 hour slots?
 
“With City Power, you have for example Orlando substation that feeds almost 20 substations, which may translate to 20 suburbs or townships such as Lenasia, Eldorado, Mulbaryon, Nirvana, Mondeor etc., most of which are in different geographic areas.”

“If we switch off Orlando, all those suburbs are going to be affected. So unlike other municipalities, we don’t have the luxury to separate our network blocks for now,” he said.
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Then don't switch off Orlando substation, switch off some of those 20 substation its feeds for 2 hours, then the rest the other 2 hours... DUH!
 
As a Johannesburg resident, I support this. As the most important South Africans and natural heros of our country, it is fitting for us to sacrifice more. When the hipsters of the Western Cape and the sex addicts of KZN look to Johannesburg, they think "There are men that we are proud to follow".

Our sacrifice in this matter, our ascetic nature and our stoic fortitude will reinforce our position as heroes that bring hope to others.
 
Hanno Labuschagne said:

Why load-shedding in Johannesburg lasts 4 hours​

Johannesburg residents are among the only South Africans who experience four-and-a-half hours of load-shedding under stage 2, with most other South Africans only being subject to two-hour blackout periods.

Eskom recently rectified this for the areas of Johannesburg that it supplies, but City Power, which supplies power to the majority of built-up areas in Johannesburg, said its load-shedding schedule will remain unchanged.

This is because the nature of the electricity grid in Johannesburg makes it impossible to reduce load-shedding periods to two hours.
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1611046213829.png
 
Well If that damn colonialist government of the past planned better and made the network better for switching off small sections easily 5 times a day!:mad: I mean what were they thinking.
 
wingnut771 said:
:thumbsup: 4 hours of geysers cooling and fridges/freezers warming is worse than 2 hours.
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Exactly. The longer the suburb is off the more geysers and fridge mechanical thermostats activate while the power is off.
Geysers especially have no delay so they draw maximum power immediately when the power is restored thus causing a massive current spike.

Thus it causes more load on the local substations immediately leading to fires and trips.
 
Louis72 said:
Exactly. The longer the suburb is off the more geysers and fridge mechanical thermostats activate while the power is off.
Geysers especially have no delay so they draw maximum power immediately when the power is restored thus causing a massive current spike.

Thus it causes more load on the local substations immediately leading to fires and trips.
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and if people were good little citizens and turn off their geysers during loadshedding and wait an hour or 2 to turn them back on, they probably wouldn't be sitting in the dark for another few hours after it was supposed to come back on.
 
wingnut771 said:
and if people were good little citizens and turn off their geysers during loadshedding and wait an hour or 2 to turn them back on, they probably wouldn't be sitting in the dark for another few hours after it was supposed to come back on.
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And if Eskom wasn't a useless piece of **** and actually do what they're being paid to do, we probably wouldn't be sitting in the dark at all.
 
supersunbird said:
Then don't switch off Orlando substation, switch off some of those 20 substation its feeds for 2 hours, then the rest the other 2 hours... DUH!
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They don't have the manpower to do this. City power has no qualified heavy current elec engineers working for them last I heard. Just some contractors.
 
Louis72 said:
Exactly. The longer the suburb is off the more geysers and fridge mechanical thermostats activate while the power is off.
Geysers especially have no delay so they draw maximum power immediately when the power is restored thus causing a massive current spike.

Thus it causes more load on the local substations immediately leading to fires and trips.
Click to expand...
This is correct in spirit, but in reality it's a bit more complicated.

On the geyser side, residential thermostats have a hysteresis of approximately 2.5 degC and most houses have mixer taps everywhere. So it's less a function of standing losses and more how much water you pull from the geyser to trigger the thermostat. This is likely correlated with the time-of-day of the loadshedding vs the duration (evening vs midday).

SA geysers must be at least Class B. Which equates to 8 - 10 degC over 24 hours for a 150l geyser. 4.5 hours at this rate is not enough to trigger the thermostat (but only if you don't pull any hot water).

Point being, I don't see how shortening the duration will make a real difference in 1000's of geysers turning on at the same time.

On the refrigeration side, the inrush is to kickstart the compressor. This has nothing to do with how long it's been off.

This kind of narrative puts some responsibility on citizens ("turn off your geyser").

It's not that I don't agree with you in principle, I just think the blame is elsewhere. Changing the duration of loadshedding is good for morale, but I don't see how it will fix the constant trips/issues when the power needs to come back on.

The real issue is that the INFRASTRUCTURE was never maintained. The substations are old and not deigned to be switched so often. As Joburg densified (complexes everywhere), lots of subdivisions in the suburbs where one house becomes 4 - 10 units. All of this still tied into the same infrastructure without increasing it's capacity.

The same for sewage, many suburbs have sewage issues for the same reason.

The City of Joburg has an official densification agenda so things are only going to get worse.
 
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