Rcd tripping problem

[Bobby671]

Hi all i have a problem on a park homes site the electric supply was upgraded 2 years ago due to the homes kept blowing the transformer. So a new 3 phase 130amp per phase has been installed, I have been working there for a couple of months know and a problem has been accurring before I started. The problem is that nearly everyday between 7 and 9 in the morning and 5 and 8 at night the rcd around the park in about 80% of the homes will trip together at the same time. There all all on different phases and they have all separate metres. I've tested all the parks cabling and nothing has stood out. The earth readings are high at the sub stations around 44.5. But I don't think this is the problem. I have volt drop through the system to 6v when in load conditions. Are applied which again doesn't really cause a problem. I've checked all the usual stuff neutral faults and I can't find any.  Does any one have any ideas. 

Thanks sorry for the long write up

 

[Essex1]

Is it definitely only an RCD and not an RCBO.?

 

[Bobby671]

Yes it's the rcd in the homes that's tripping  and it's got me how most of them are tripping at the same time all around the caravan park there basically static caravans.  But all fed from different parts of the park

 

[Essex1]

So lots of different RCDs are tripping at roughly the same time?

 

[phil d]

the clue seems to be tripping at peak times,highest load,given they are split across 3 phases then I'd definately say look for a neutral fault,certain faults only show up under high load.

 

[Murdoch]

How many caravans are being used at the same time? Sounds like the supply is the problem..... 7-9 and 5-8 peak times IMHO

 

[ProDave]

Assuming you have tested the individual 'vans and confirm there are no real I/R issues with any of them?

My money would be a voltage spike occuring, perhaps a very large load elsewhere turning on, and that's causing a spurious trip.

Are the rcd's that are tripping inside the individual 'vans, or in site distribution boxes?  More importantly are they all the same make (less likely if they are in the individual 'vans)?

Any of them on off peak supplies and using storage heaters?

 

[Bobby671]

I have tried and run out of ideas the park has 4 sub stations and 1 main unit if there a neutral fault then I would have thought it would be at the distribution room as that's the only place all the homes are connected but everything test out fine. Ib had the yedl out to make sure the supply is stable for the amount of load that's being used in the mornings . Any body had this problem before as I'm stuck and if it's a neutral fault how would it be only 80% of the homes go off I would have thought they all would as they are protected with a 30ma rcd

 

[Bobby671]

All vans tested and work fine ,all the rcd in the vans are different and the rcd are tripping in the individual vans. There also time delayed 100ma rcd protecting the cable going to the homes too. Basically everything has an rcd but only in the vans that are tripping  can volt drop cause it as I get a 6 v drop know if under a lot of load could it be possible the main supply drop by 6 v then I would have a big volt drop which would cause current to increase but I don't know why that would trip the individual homes out 

 

[NozSpark]

Are they active or passive RCD's????

 

[binky]

might be worth getting DNO to install a data logger on the incoming supply. Have you checked loadings per phase are balanced? Is there anything large like a swimming pool?

 

[Bobby671]

They are passive rcds.  Data logger getting fit tomoz  And testing on the incoming supply already been done there already saying it's going to be a problem at my end in the park. The phases are balanced 1 phase 57 amp phase 2 48 amp and phase 3 36 amp. No there's no swimming pool and there is no motors to kick in.

 

[NozSpark]

Are there any BIG industrial units near by?

 

[Blue Duck]

Are there any BIG industrial units near by?

Near a a caravan park!? :slap

 

[NozSpark]

Near a a caravan park!? :slap

You'd hope not,,,,, but you never know :coat

 

[Manator]

I booked a caravan holiday once in Scotland, looked great and close to the sea. What they failed to say was that it was close to a nuclear power station.

 

[ProDave]

That should have kept you warm at night then.

 

[roys]

I booked a caravan holiday once in Scotland, looked great and close to the sea. What they failed to say was that it was close to a nuclear power station.

Was it near Dunbar by chance?

 

[Manator]

It was a long time ago but yes I think it was @roys

 

[Blue Duck]

There's a lot of "caravan" sites in London, often next to industrial areas., not sure you'd be welcome to stay the night but they are always very friendly especially if you wish to buy a laptop, speakers, 50" tv or a memory foam mattress.