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nashton

I have recently had problems with 3 different RCDs but the problem with each was similar. I was called out to sort trip trouble on an RCD (30mA) in a house, client claming that a chainsaw (class 2) kept triping RCD, however no fault was found. Also the RCD pased all normal tests (trip times and ramp tests). However on changing RCD for a new one the problem stopped, and have had this problem two other times. Only common link seems to be age of RCD and items with a PCB causing the problem. Could anyone make a sugestion please.
 
Whats was your ramp value ? I would clamp the tails when the chain saw was switched on to see what sort of leakage it had. It could be the new RCD has a slightly higher earth leakage stopping the coil tripping out.

Also it also depends on what else is switched on as the earth leakage on the RCD soon adds up IMO !!!
 
Whats was your ramp value ? I would clamp the tails when the chain saw was switched on to see what sort of leakage it had. It could be the new RCD has a slightly higher earth leakage stopping the coil tripping out.

Also it also depends on what else is switched on as the earth leakage on the RCD soon adds up IMO !!!

The chainsaw is class 2 and it will have no earth leakage.
 
Snap!............ Just changed D/Board.Temporary Double socket installed fed from New RCBO. Went to plug in a SDS class II and it tripped. Tested again .All okay. Plugged in a Class II Fluor/Lead Light and tripped again. Plugged a Masterplug RCD/trailing socket in everything works on this. So I am going to try a Rcd /Double socket /Faceplate.
 
Induced current in the cpc from startup maybe? Would be worth having an extension lead (with inner cores exposed) clamped to see if there's anything on the cpc if you can recreate it.
 
The fact that both are saying that they are plugging in class II equipment would mean that there can be no earth leakage

No earth leakage directly due to a fault as there is no cpc to it. It can still induce a current in the cpc at the socket though (at least I would suspect as much).
 
1) it is an RCD, not an RCBO.
2) earth leakage measured using a clamp meter is around 10-15mA, and using the chain saw sometimes adds nothing, but sometimes causes a momentary spike of around 20-25mA This spike does not cause the RCD to operate, though im not sure how a class 2 bit of kit can cause a spike.
3)ramp test tripping at 27mA

The new RCD i fitted was exactly the same in every respect except it has never been in service. There has been a sugestion that a capacitor in PCBs could cause a problem????
 
That's possible, it would depend on the size of the capacitor and the circuit (preceding resistor, RC circuit etc) as to how long it would take to charge.

Edit: could even be a discharge somewhere.
 
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No earth leakage directly due to a fault as there is no cpc to it. It can still induce a current in the cpc at the socket though (at least I would suspect as much).

Would an induced current in the cpc affect the RCD which operates on imbalance of the P-N apart from the MEM ones which have the earth reference wire to detect nuetral loss and DC spikes?
 
May we assume that the chainsaw is mains voltage and not 110V (via a transformer)?

Think I'm leaning towards the capacitor theory atm. Not sure how you'd prove it easily though.
 

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