Earth leakage trips everytime loadshedding ends

[rodga]

Apologies took a bit of a break thanks to load shedding

I have a customer with those red plug tops on just about every extension plug ... no tripping issues.

I rewired the building 3 weeks ago and fitted 2 earth leakage units per DB ... no CBI earth earth earth leakages were used on the site.

the callouts I attended to recently ... all had CBI earth earth leakage units.

The old ELU was not a CBI and had the same issue. Still have it in the garage so will take a pic later.

Very good point on the surge arrestors. That is why now they want us to use a spark gap SPD for the Neutral. As the MOV can after time break down and leak to earth.
Also they kinda say to install the MOV spd afyer ELU for that reason.

Kicking my self for not thinking of that as done a fair bit of CPD stuff on it and slowly getting to grips... and having a whole lot more questions everytime I learn something hahaha.

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What is an MOV and SPD?

I think most of us have been called out for similar problems earth leakage tripping at the resumption of power after loadshedding.

Here are my experiences.

1. Old Heineman 20mA earth leakage relays. Replaced earth leakage relay, problem solved. ELU was replaced with a new CBI, no change. Will use the old one to seperate the circuits on the earth leakage.

2. Create your own load shedding with the main switch. If earth leakage trips then repeat process with a circuit isolated.
If fault persists then repeat with more circuits isolated until earth leakage does not trip when mains are turned on.

Have tried this before, but it does not reproduce the problem. Will try it again though.


3. Install 2nd earth leakage and put all the circuits that were isolated, throufh it. Will reuse the old one

4. Do final testing.

The above method has solved the problem everytime for me.

We must remember that there are sometimes huge surges when power is switched on after loadshedding which aggrevate the situation. I do think this may be the issue

The neatest solution I have personally seen to avoid any power surges after loadshedding is to take the mains through a contactor that is energised by a delay on timer so that your power only comes on a minute or two after everyone else's. By the time your power comes on then all those nasty surges have already done their thing to everyone else. Do you perhaps have a link to such a device?

Sorry for the long essay

Peace out .. Derek

If you are going to go to that expense ... I would strongly advise you instal a trip connect unit ... it will prevent the contactor reenergising and a time can be set on the unit ... if the neutral is missing resulting in higher than normal voltage (600+ VAC) Link please. I would like to research as much as possible so I at least know what the electrician is talking about when they do come. lol

From years of experience with load shedding ... it will stop in a couple weeks ... everyone forgets about it ... then suddenly it is at the top of everyone's list again ... generator sales go through the roof ... battery inverter prices go crazy and so the cycle just goes round and round.

A little forward panning will not only save a ton of cash ... but also prevent issue with your electronics ... which might not fail today or tomorrow ... but will fail sooner or later.

Just to add, this issue has been present since we moved in 2017 so it is not something that started after I added something to system.

Thanks for all the comments thus far.

[rodga]

Missed this one in my multi quote

We have been finding that the surge arrestor type plug tops that are there to protect equipment are also causing problems when power comes back on after load shedding .
The surge arrestor will take the spikes down to earth and the earth leakage sees it as a fault , which is correct , and it is doing it's job and so is the surge arrestor.

Bit of a catch 22 situation

A lot of the new fridges etc have mosfet's which are also doing it

Best would be to install an extra ELU and put fridge etc on a dedicated circuit.

Best way to test is unplug the fridge on the next load shed , maybe TV as well , computers , routers ,also any surge arrestor type plug tops and see if the problem disappears .

Would be interested to hear the feed back. I think I only have one of these surge arrestors but will check it out, and will let you know what happens

We have all the testers in the world , including a leakage current clamp , and have struggled on some of the intermittent faults of late.
I had a query on Friday , with a 200Kva genset . On load shed to generator , everything fine , from genset back to mains the main CB trips instantly. Reset immediately and all is fine. I suggested disconnecting the surge arrestors as a test and have not heard back. Installation has not changed in the past 2 years , maybe the surge arrestors where getting tired or the inrush current settings on the CB had been adjusted or got tired.
There are lot's of funny's happening at the moment and I have picked up that the frequency is jumping every 2 hours on sites that I can access and monitor. The sites are 300Km apart , so it is an Eskom thing.

As per my previous post, this issue has been here since we moved here in 2017

[AndyD]

We have been finding that the surge arrestor type plug tops that are there to protect equipment are also causing problems when power comes back on after load shedding .
The surge arrestor will take the spikes down to earth and the earth leakage sees it as a fault , which is correct , and it is doing it's job and so is the surge arrestor.

Bit of a catch 22 situation

A lot of the new fridges etc have mosfet's which are also doing it

Best would be to install an extra ELU and put fridge etc on a dedicated circuit.

Best way to test is unplug the fridge on the next load shed , maybe TV as well , computers , routers ,also any surge arrestor type plug tops and see if the problem disappears .

Would be interested to hear the feed back.

We have all the testers in the world , including a leakage current clamp , and have struggled on some of the intermittent faults of late.
I had a query on Friday , with a 200Kva genset . On load shed to generator , everything fine , from genset back to mains the main CB trips instantly. Reset immediately and all is fine. I suggested disconnecting the surge arrestors as a test and have not heard back. Installation has not changed in the past 2 years , maybe the surge arrestors where getting tired or the inrush current settings on the CB had been adjusted or got tired.
There are lot's of funny's happening at the moment and I have picked up that the frequency is jumping every 2 hours on sites that I can access and monitor. The sites are 300Km apart , so it is an Eskom thing.

Surge arrestors would be worth ruling out, it's possible there could be a voltage spike on power reset that's causing them to conduct. I think some earth leakages are more prone to tripping due to phase shift that could be occuring momentarily when power comes back on and the load isn't linear. Same with harmonics...

I've had several cases where earth leakages trip and they're testing fine on a full ramp and function test but replacing them with a different make has sorted out the problem. Not loadshedding related but I've also a problem where an earth leakage was tripping once a day and every day around suppertime. I eventually proved it happened every time the streetlight right outside the property switched on even though the streetlights were on a different supply and nothing to do with the house supply. It turned out that particular RCD was sensitive to harmonics from the inductive ballast and starter.

[ians]

I think we have discussed those little red mother F^&*ers in the past (ellie surge plug tops) ... they have cause many wasted hours trying to trace intermittent faults (not related to load shedding) ... just random tripping ... using the 250 Volt setting on the insulation resistance test ... identifies that issue quickly.

[Derlyn]

@Rodga

The fact that you cannot re create the fault with the main switch seems to indicate that the fault is NOT on your installation but is caused by an unwanted characteristic on the supply when switched on by the supplier after loadshedding.

What that characteristic is, is hard to say, but I suppose it is either spikes, high voltage or something luke that in which case the delayed energising of your supply by means of a contactor will solve the problem.

I do not know of a plug and play unit available but one can make up a unit using a contactor and a fridge safe unit that is sold by Ellies. Install a dedicated plug close to the db that is supplied directly from the main switch through the necessary circuit breaker.

Now plug the fridge safe unit into that plug. When the power comes on after loadshedding, this unit checks the supply for any abnormalities before turning on the output. This output is used to energise the contactor that turns the mains on to everything else including the earth leakage relay. The fridge safe has a monitoring period of about 3 minutes so your load shedding will be 3 minutes longer than your neighbours.

There is the added advantage that this unit constantly checks the supply and should there be any abnormality at any time, it will disconnect your installation from the supply and re connect automatically again after 3 minutes should the supply be back to normal.

Hope this helps

Peace out .. Derek.

[rodga]

@Rodga

The fact that you cannot re create the fault with the main switch seems to indicate that the fault is NOT on your installation but is caused by an unwanted characteristic on the supply when switched on by the supplier after loadshedding.

What that characteristic is, is hard to say, but I suppose it is either spikes, high voltage or something luke that in which case the delayed energising of your supply by means of a contactor will solve the problem.

I do not know of a plug and play unit available but one can make up a unit using a contactor and a fridge safe unit that is sold by Ellies. Install a dedicated plug close to the db that is supplied directly from the main switch through the necessary circuit breaker.

Now plug the fridge safe unit into that plug. When the power comes on after loadshedding, this unit checks the supply for any abnormalities before turning on the output. This output is used to energise the contactor that turns the mains on to everything else including the earth leakage relay. The fridge safe has a monitoring period of about 3 minutes so your load shedding will be 3 minutes longer than your neighbours.

There is the added advantage that this unit constantly checks the supply and should there be any abnormality at any time, it will disconnect your installation from the supply and re connect automatically again after 3 minutes should the supply be back to normal.

Hope this helps

Peace out .. Derek.

Hi Derek, yesterday during load shedding I dropped the mains switch and waited for power to be restored before turning it on again. Everything turned on as expected without any issues.
I do think splitting the loads over 2 elcb will still be useful which will enable us to isolate any faults easier.

Is what @ians mentioned earlier, the trip connect unit, not the same thing you are recommending?
I googled trip conncet unit and this is what I found:
https://surgeprotection.co.za/produc...t-single-phase

[Derlyn]

Hi Derek, yesterday during load shedding I dropped the mains switch and waited for power to be restored before turning it on again. Everything turned on as expected without any issues.
I do think splitting the loads over 2 elcb will still be useful which will enable us to isolate any faults easier.

Is what @ians mentioned earlier, the trip connect unit, not the same thing you are recommending?
I googled trip conncet unit and this is what I found:
https://surgeprotection.co.za/produc...t-single-phase

I personally don't think it's going to solve the problem.
Your 2 earth leakages are still going to be subjected to the same incoming supply which is the suspected cause of the trip. Installing an extra earth leakage is only going to solve the problem if the problem can be re created with the mains switch thus proving that the fault is actually on the installation.
Anyway, It will be interesting to know the outcome.

The trip connect does basically the same as the fridge safe unit.
One will still require a contactor irrespective of which one you use.

Spec sheet of fridge safe unit:
http://e-systems.co.za/System/FabSheets/4FEAFG16.pdf

A tv safe unit can also be used. In my opinion, a better option.

The spec sheet of the tv safe unit:
http://e-systems.co.za/System/FabSheets/2FEATVG16.pdf

Keep us posted.

Peace out .. Derek.

Edited 17.51 to include tv safe specs.

[ians]

Not the same thing ... the trip connect is installed at the mains ... we had a stage were neutrals were being stolen in the sub station ... the trip was correct device for that application ... this fridge device is something else.

A word of warning ... if you buy surge protection devices for you computer fridge or whatever ... if you want to qualify for the damage claim ... YOU MUST REGISTER the product.



https://www.ellies.co.za/product/fridge-safe/

[Derlyn]

Not the same thing ... the trip connect is installed at the mains ... we had a stage were neutrals were being stolen in the sub station ... the trip was correct device for that application ... this fridge device is something else.

A word of warning ... if you buy surge protection devices for you computer fridge or whatever ... if you want to qualify for the damage claim ... YOU MUST REGISTER the product.



https://www.ellies.co.za/product/fridge-safe/

If either the fridge safe or the tv safe sees no neutral, neither of them will turn on the supply. So they do also check for a lost neutral.
I don't know where you picked up that they need to be registered. Registered with who ?

If you use either of them, it should not be necessary to claim for damages ....

I'm speaking under correction but Justloadit has a similar product and it will be interesting to hear his take.

Peace out ... Derek

[Dylboy]

Very cool and good info on those two devices ! I have for awhile wanted to look into this stuff as had a few clients with the Neutral stollen. Was looking at relays but this two seem to tick boxes which is great.
Thank you gents !

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