Hi,

I run 2 inverters of the same make on the house supply, again, not using both at the same time and i've not had a problem like this, you have to investigate what the tripping current is on the RCD (i have a seperate RCD in my work shop), it could be an over current or some wires have been crossed somewhere and it's shorting. This could be many possible reasons for this.

Michael W

The supply to my inverter was professionally installed and on the advice of the inverter supplier is not via an RCD. It has a 20 A breaker and two independent earth connections.

Very often inverters has a filter near the input connection

you can switch/unplug this

look in the book for instructions

if the filter is installed it will trip the rcd

I'd go the way Stuart describes but i have to say I find the whole question of VFD and RCD's baffling when I was working I had lot's of problems with tripping something to do with earth leakage if I remember correctly, but it's just accured to that both my shed and workshop are fed from RCD's and never had a problem

H

John C,

I don't have an inverter in my workshop, but all the various garden services are supplied from the workshop consumer unit; these include two pond pumps which I know to be 'lossy' things anyway each with measurable leakage to earth.

After we had a PV system installed we started getting earth leakage tripping at irregular intervals and our installer rewired the system via its own dedicated circuit. He confirmed that the PV inverter itself produced about 10mA earth leakage and any other stray leakage elsewhere could easily lead to enough to trip the house breaker.

On his advice I later on had our own electrician fit a further earth leakage protected unit in the supply to the workshop, which was, and this is the crucial bit, referenced back to its own local dedicated earth rod so that the house breaker was no longer 'seeing' any leakage on the workshop power supply. The two 'earths' operate completely independent of each other.

End of problem.

Inverters all need a degree of earth leakage loss to work anyway and it may be that you have altered the conditions domestically such that your house breaker is now reading a total loss approaching 30mA.

My electrician convinced me that all is well with my new arrangement, for example the effect of damper soil where the earth rod is installed can be dramatic, just pouring a watering can full round it will make a big difference, and with variable soil conditions it is all a purely relative business anyway.

I hope that provides some food for thought.

Brian

From memory, it was the EMC filter that was likely to trip a RCD rather than the inverter itself. I do have a separate EMC filter on my inverter.

Hi Stuart,

your correct, something I overlooked.

I originally thought it was the filter and I was gonna modify it, turned out the filter was all integrated, some ferrites, one capacitor across the output, the rectifier and then the large inverter filter capacitors, nothing to ground apart from these inverter caps. just a common mode filter in my case which is why it could only be the large filters for me.

I've not had an RCD tripping but I have had the welder tripping the MCB. The mains cable from MCB to power socket was quite short (DB was in workshop). The tripping stopped when I put a long extension cable on the welder supply. I don't know why – I've forgotten all the 'tricky electrics" I ever knew.

I also have a digital readout on the mill DRO switching off when I start the mill motor. The mill motor is single phase a with a capacitor. I have a gut feeling the capacitor start motor is causing a spike in the circuit – just a gut feeling, no theory to back it up – so I have just bought a surge protector to see if that will stop the DRO readout switching off.

Sorry if that has diverted the thread a bit, but it was sort of related. It's electrical and a trip!

I have a rule. NEVER trust anything with wires coming out of it. Tricky animals, electrical stuff.

Chris

The solution to John Cs problem is to have the shed on its own RCD. It may help if the tripping is caused by cumulative earth leaks and at least it wont be a nuisance to the people indoors when it does trip.

I have occasional problems with the RCD tripping when I switch on my 2HP inverter (momentary surge to earth from the RFI filter?)

My MCB frequently trips when I power up my arc welder or 110V site transformer (transformer inrush current)

As with ChrisH, an extension lead helps to alleviate the problems (adds a bit of resistance?)

A small inductor would probably have the same effect, any experts able to comment on this?

Dave

I had to change an inverter on friday on a very large walk in industrial washing machine, I switched the machine off and gave it the obligatory 5 mins then started undoing the three phase wires when I touched the blade of my screw driver, I got a belt from the capacitors.

When we install our inverters we use 3 core + earth, screened cable, the screening is earthed with the earth wire, as the interference can drive the Siemens S7 PLC nuts, maybe its something to do with that.

Martin P

re RCd tripping, I am at the moment having a new kitchen installed, all the power to the kitchen is off but the main house rcd has tripped 4 times in 1 day due to the plasterer moving the dead ring main wires around in the back boxes, explain that. crashed the computer several times, not so happy. David