Any ideas Please

[mayfair]

Hi Guys
Been to a warehouse today large cooler room main MCB 40A 4 pole N L1L2L3 plus 40A 30ma Diff it all works fine until the compresor shuts off then the Main MCB trips ...not the diff the mcb if you put i back on all is fine even if compresor dont start. Any thoughts my brain hurts.
Cheers
Gary

 

[shanky887614]

1 sec

so its the mcb tripping but not the rcbo?

can we get a picture please?


are you sure its not a rcd main switch?

 

[mayfair]

As I said its the main breaker not the RCD

 

[shanky887614]

surely you would have a bigger main switch than rcd though. and we have been using rcd main switches recently[emoji20]

 

[Guest77]

One thought, it could be possible when the compressor for the fridge stops the stat is energised because it needs to take over to maintain the temperature and it could be faulty and shorting out hense the short circuit and the fact the MCB is blowing, then again it may be something completely different.

 

[Marvo]

Is the compressor contactor operating anything when in the off position like a sump heater or defrost element that could have a fault maybe?

Can you upload some pics of the controls?

 

[Guest77]

1 sec

so its the mcb tripping but not the rcbo?

can we get a picture please?


are you sure its not a rcd main switch?

Silly Boy

 

[mayfair]

will do thanks for your input

Is the compressor contactor operating anything when in the off position like a sump heater or defrost element that could have a fault maybe?

Can you upload some pics of the controls?

 

[mayfair]

Looks like (Fingers crossed) it was the thermostat arcing not done it since it was changed at 8.00 am this morning still dont know why the rcd didnt drop out ramped it and seems ok. As my old lecturer used to say its fixed be happy with that and stop foofing around with it now. Thanks for input apart from #2 which i still dont understand

 

[Guest77]

Looks like (Fingers crossed) it was the thermostat arcing not done it since it was changed at 8.00 am this morning still dont know why the rcd didnt drop out ramped it and seems ok. As my old lecturer used to say its fixed be happy with that and stop foofing around with it now. Thanks for input apart from #2 which i still dont understand

So I was right then?

 

[mayfair]

Does this now mean Im a 1day fridge engineer.......Sod that give me some a graet big DB to wire up any day of the week

 

[Marvo]

Glad it's up and running again although I'm not sure why an arcing t/stat would be the cause. I enjoy refrigeration work, it's interesting controls and it makes a nice change to the run of the mill stuff.