Load shedding is back?

[Turiko]

At 10:15am everyday our ripple controlled geysers are turned back on.

Which could be avoided as the more modern receivers have provision for programming a random delay on switching.

The system I am developing already has it, am generating a random time delay using hardware.

 

[Praeses]

Got a blackout here, not within the scheduled shedding time. So glad i charged my phone last night

 

[Paulr]

Which could be avoided as the more modern receivers have provision for programming a random delay on switching.

The system I am developing already has it, am generating a random time delay using hardware.

That makes a lot of sense.

As a matter of interest, what is the random time delay window?

 

[Turiko]

On my system I can set the relay to either respond immediately or to respond randomly between 1 - 60 minutes. I haven't written the code to do so entirely yet because I am still doing research to see what is the 'optimal' time window but I will soon.

The relays I ordered arrived eventually, good for 40A or the average 150 litre geyser.

Am so tied up at the moment with other business engagements so I haven't worked on this little project for over 2 weeks but I will soon. I did put a picture of my prototype in my album, if you look under my profile it is there.

 

[Moederloos]

Same thing again today - except the outage lasted for about 5 seconds.
Same time.

What a stupid system.

 

[Turiko]

Indeedy- would love to know what the cause is. I suspect maybe ripple control system is borked again and there's a delay of 5 seconds due to errors or something of that nature. I am not currently logging else I would have been able to check for you.

 

[Moederloos]

Indeedy- would love to know what the cause is. I suspect maybe ripple control system is borked again and there's a delay of 5 seconds due to errors or something of that nature. I am not currently logging else I would have been able to check for you.

My guess is that it is a sudden massive draw on the power grid.
Geysers in our area get turned off between 6am and 10:15am and again from 5:30pm to around 9pm (never gone to look at 9pm at night to check - but my pre-paid meter starts ticking over at 9 or so every night).

Now, since it is winter, and the ambient water is very cold, add to that people use water before work, and we have a ready-made surge at 10:15 when 20-50 000 geysers (min) switch back on...

 

[Turiko]

@Moederloos
Most likely, but hopefully I will be back at home in my office next week, and I can plug the stuff back in and have a look see...

You seem to have indicated you live close to me? Either way send me a pic of your ripple receiver and we can take it from there.

 

[Generator Man]

My guess is that it is a sudden massive draw on the power grid.
Geysers in our area get turned off between 6am and 10:15am and again from 5:30pm to around 9pm (never gone to look at 9pm at night to check - but my pre-paid meter starts ticking over at 9 or so every night).

Now, since it is winter, and the ambient water is very cold, add to that people use water before work, and we have a ready-made surge at 10:15 when 20-50 000 geysers (min) switch back on...

If thats the case, wait for sub-stations exploding in the not too distant future. Thats perfect recipe for massive voltage spikes of the kinds we saw when load shedding was carried out, only difference is that the stations tripping due to over-load is a whole new kettle of fish...

 

[Moederloos]

If thats the case, wait for sub-stations exploding in the not too distant future. Thats perfect recipe for massive voltage spikes of the kinds we saw when load shedding was carried out, only difference is that the stations tripping due to over-load is a whole new kettle of fish...

Perhaps - the difference here is that the ripple control units are more likely than not designed for the twice-daily on/off cycle where the entire substation is not.
The massive draw on power, when the grid is so highly constrained, is cause for worry though.

 

[Turiko]

ripple control units are more likely than not designed for the twice-daily on/off cycle

Correct. Some of the older ones are happily working still AFTER 30 YEARS. I have such one I use for development even though the springs have snapped now and some parts are worn.
The relays I got recently for my product I am developing, are specced at more than 300,000 switching operations under full load. They are really robust. I would venture to say the electronics stands a better chance of dying of age than the relay.

The massive draw on power, when the grid is so highly constrained, is cause for worry though

Indeed it is, and it can be eliminated but guess what, no-one is interested in backing my small company to make this happen I blame all this BEE stuff for that. City power is running with ANTIQUE equipment, stuff that should be in a museum and no wonder we have streetlights on during the day and these 5 second breaks and overloads.

The transformer exploding thing, that's due to the oil- the oil needs to be taken care of and the people who had the know-how are no longer with us. City Power also ignores the experts in this field, just like they ignore me with respect to the ripple control system. They don't want to spend money on maintenance or upgrades, because they're shoving the cash into their pockets. Many transformers are also beyond their service life. A good example is those at Hursthill near Brixton in JHB, they are so old, the company that made them no longer exists....

 

[Generator Man]

Perhaps - the difference here is that the ripple control units are more likely than not designed for the twice-daily on/off cycle where the entire substation is not.
The massive draw on power, when the grid is so highly constrained, is cause for worry though.

I would love to hook up a voltmeter onto the main feed in the areas where these momentary blackouts occour, just to check if the power is going off altogether, or the voltage is simply dropping below the operating treshold of 220v equipment.
If it's the latter, than I'm afraid that it's bad news on equipment connected at the time. Also would be interesting to see if the voltage spikes when it comes back online, in the case of the former.

The substations blew up during loadshedding, due to a few factors working together to create a mess. Many of the transformers haven't been serviced for a long while, thus carbon buildup in the transformer's oil (as we all know carbon is conductive) would create a short between windings. Carbon buildup was increased due to turning the substations on and off, and the resulting voltage spikes would further increase the chances of shorting between the transformer's windings.

If these transformers get overloaded due to thousands of ripple switches getting turned on at the same time, it can't bode well either.

 

[Turiko]

just to check if the power is going off altogether,

It is dying altogether, my ripple monitoring system resets, I lose control of it and to do that you need a loss of mains of at least 6s (due to large PSU capacitance)

thus carbon buildup in the transformer's oil

Actually, (and I got this from a company that does the preventative maintenance) it is moisture getting into the oil because they don't recondition it nor do they check the breathers and oil seals. I am currently trying to get them to post on this forum, it would also help if I can find their darned URL because it was on my portable HDD which the bastards stole when they broke into my house.

Paper insulation is used esp. on older transformers and this attracts the moisture and causes partial shorts across windings. Got this from the experts...

In a transformer, all you have is a lot of copper windings in a steel tank full of oil, with a bit of dried air at the top. No real source of carbon, unless a part. short is already in progress.

However, in an EHT circuit breaker, the oil is used to quench the arc drawn when the contacts open. Potentially a source of carbon however all the literature I read speak of the oil liberating a gas, not carbon! The design of EHT circuit breakers is not new, there has been development since the 1930's because back then they already had oil blast explosion pot technology(1) in 132kV switchgear. There's even newer technology available now using compressed air (2) and I find it hard it concieve that these products in use were not engineered for a certain duty cycle.

References:
(1) General Electrical Engineering- Philip Kemp (published 1944)
(2) Electrical Power Systems - M.N. Bandyopadhyay (2006 - Prentice Hall)

 

[Generator Man]

It is dying altogether, my ripple monitoring system resets, I lose control of it and to do that you need a loss of mains of at least 6s (due to large PSU capacitance)


Actually, (and I got this from a company that does the preventative maintenance) it is moisture getting into the oil because they don't recondition it nor do they check the breathers and oil seals. I am currently trying to get them to post on this forum, it would also help if I can find their darned URL because it was on my portable HDD which the bastards stole when they broke into my house.

Paper insulation is used esp. on older transformers and this attracts the moisture and causes partial shorts across windings. Got this from the experts...

In a transformer, all you have is a lot of copper windings in a steel tank full of oil, with a bit of dried air at the top. No real source of carbon, unless a part. short is already in progress.

However, in an EHT circuit breaker, the oil is used to quench the arc drawn when the contacts open. Potentially a source of carbon however all the literature I read speak of the oil liberating a gas, not carbon! The design of EHT circuit breakers is not new, there has been development since the 1930's because back then they already had oil blast explosion pot technology(1) in 132kV switchgear. There's even newer technology available now using compressed air (2) and I find it hard it concieve that these products in use were not engineered for a certain duty cycle.

References:
(1) General Electrical Engineering- Philip Kemp (published 1944)
(2) Electrical Power Systems - M.N. Bandyopadhyay (2006 - Prentice Hall)

Thanks for the explanation. I was always of the impression, and spoke to enough people that work on transformers to believe it was actually a carbon build up problem.

I see you work with a company afiliated with Eskom? Whats the current situation WRT demand and supply? Consumption at the moment must be pretty close to yearly peak, with the cold setting in and people upping usage?

Our area (East Rand) was hit several times last night and this morning, but not 2 hours intervals as usual, I think it was more faults than load shedding.

 

[Turiko]

I was always of the impression, and spoke to enough people that work on transformers to believe it was actually a carbon build up problem.

I was also under the impression that it was the breakdown by-products of the oil, but back in 2005 I was very embarassed when I was publicly corrected by a rep from that company and then then began to explain to me the exact chemistries inside a transformer. There is carbon involved eventually yes, but what happens is the paper starts to burn and becomes carbon which conducts and what happens is these pieces of paper flake off and fall across HV windings causing a flame which sets the oil alight. I tried this in the lab and it is indeed the case. Even chipboard does this and whilst the carbon just gets hot, it unfortunately ignites the oil and any other flammable liquid in it's path.

To summarize: It all has to do with contamination of the oil, which occurs over time when un-dried air gets into the transformer. They neglect to maintain or otherwise replenish the silica gel in the breather muffler and sometimes thieves break the snorkel off and sell it for scrap metal. Sometimes transformers get a leak and moist air gets in.

I see you work with a company afiliated with Eskom?

No I own my own company. I am doing research, Eskom is providing me with some answers. They contacted me because they think my work might be of value to them.

Whats the current situation WRT demand and supply? Consumption at the moment must be pretty close to yearly peak, with the cold setting in and people upping usage?

They told me that the municipalities, combined with the commitment of some companies, realized the near 10% margin they needed. The municipalities turned off the geysers more than usual, which has been confirmed by at least one forumite here. I haven't spoken to them since the loadshedding was called off... but I honestly don't think that everyone saved their 10% a lot of people personally known to me have a f-you attitude w.r.t. Eskom.

Our area (East Rand) was hit several times last night and this morning, but not 2 hours intervals as usual, I think it was more faults than load shedding.

Yip, lots of faults, have experienced them personally. As you saw some of us are experiencing the 5-minute-outage syndrome which seem to not be correlated to peak times. The last one was on a Saturday afternoon, which was pretty hot.

 

[Generator Man]

Thanks for the comprehensive reply. I also doubt the 10% saving has been reached, hence my doubts as to what Eskom says, and what is the reality.

There is no chance that we are using 10% less power, with the current cold and people switching on heaters of all kinds, compared to January/February. Also I see lots of street lights running during night & day. The only saving that might have been achieved is giving less power to the mines, and industries running generators at peak time. But still the maths do not compute.

Either Eskom doesn't want the real causes behind the load shedding/blackout (read mis-management) or they are not telling us the truth with regard to electricity importation. I know for a fact that electricity is being imported from as far out as Zambia/DRC and Mozambique, which was not the case (at least not in this quantity) back then. The other thing is that neighbouring countries (Botswana, Namibia, Lesotho and Swaziland) have had their share of electricity cut drastically.

I just fail to understand the claims of "we'll have load shedding and blackouts until 2016 at the very least" made by Eskom during the load shedding debacle, which have put several people out of business, others closed down rather than face this prospects, and others still have invested in huge power generation equipment, or moved elsewhere. Sure being transparent and telling us that it would be over in a few months would have been a better strategy?

 

[-toady-]

Thanks for the comprehensive reply. I also doubt the 10% saving has been reached, hence my doubts as to what Eskom says, and what is the reality.

There is no chance that we are using 10% less power, with the current cold and people switching on heaters of all kinds, compared to January/February. Also I see lots of street lights running during night & day. The only saving that might have been achieved is giving less power to the mines, and industries running generators at peak time. But still the maths do not compute.

Either Eskom doesn't want the real causes behind the load shedding/blackout (read mis-management) or they are not telling us the truth with regard to electricity importation. I know for a fact that electricity is being imported from as far out as Zambia/DRC and Mozambique, which was not the case (at least not in this quantity) back then. The other thing is that neighbouring countries (Botswana, Namibia, Lesotho and Swaziland) have had their share of electricity cut drastically.

I just fail to understand the claims of "we'll have load shedding and blackouts until 2016 at the very least" made by Eskom during the load shedding debacle, which have put several people out of business, others closed down rather than face this prospects, and others still have invested in huge power generation equipment, or moved elsewhere. Sure being transparent and telling us that it would be over in a few months would have been a better strategy?

Good post. Raises some very interesting questions too.... *coughs....
May I bet that the blackouts will continue way after 2016?

 

[pietb]

Good post. Raises some very interesting questions too.... *coughs....
May I bet that the blackouts will continue way after 2016?

Mmmm...jip.


I live in Jeffreys Bay and in one of the older areas close to the sea but far from the sewerage system. In our area we have septic tanks and we get to know the "Poop Truck drivers" quite well.

Last week our street experienced several "load shedding" periods. Last Sunday I saw the council bakkie at our transformer pole and I stopped to have a chat. Yes it was the Poop truck driver.

He told me that the last two qualified council electricians(white) resigned and come 1 of July no more electricians.

For those of you that don't know - Jeffreys Bay is one of the fastest developing coastal towns this side of the pond. With not a single qualified electrician as from the 1 July.

According to the Poop truck driver the qualified Civil Eng. oks also left.

That leaves us with a Poop truck driver

So if you are non white, want to enjoy the relaxed lifestyle of a developing coastal town and need an income: J -Bay is the place.

 

[Generator Man]

Mmmm...jip.


I live in Jeffreys Bay and in one of the older areas close to the sea but far from the sewerage system. In our area we have septic tanks and we get to know the "Poop Truck drivers" quite well.

Last week our street experienced several "load shedding" periods. Last Sunday I saw the council bakkie at our transformer pole and I stopped to have a chat. Yes it was the Poop truck driver.

He told me that the last two qualified council electricians(white) resigned and come 1 of July no more electricians.

For those of you that don't know - Jeffreys Bay is one of the fastest developing coastal towns this side of the pond. With not a single qualified electrician as from the 1 July.

According to the Poop truck driver the qualified Civil Eng. oks also left.

That leaves us with a Poop truck driver

So if you are non white, want to enjoy the relaxed lifestyle of a developing coastal town and need an income: J -Bay is the place.

My God, that is scary stuff.

 

[psc]

The whole network will be in a precarious state until at least post 2016. It is all a question of reserve margin, low reserver margins do not give the buffer neccessary to allow for unscheduled maintenance (which is currently quite high).

There are documents showing the current build program vs future demand and at no point is there an adequate reserve margin.