Q
qwest
Hi, I'm looking for some help and hoping I might find it here.
I am a house owner with a 10Kva stand-by generator (40Amp / single phase). I had the generator professionally installed by my local electrician but I supplied the Automatic Mains Failure switch and generator.
The set-up works perfectly with one issue - there RCDs trip. Given that the backup is supposed to be fail-safe this is far from ideal. The electricians that carried out the install have never worked with this type of equipment before so are not able to support the problem.
The generator is spiked to earth. The utility supply is PME. The PME earth is permanently connected to the generator earth spike so I believe the earth should be common to both generator supply and utility. There is no switching of earths.
The generator supplies the AMF panel through a 100mA RCD located at the generator.
The house is protected by a 100mA RCD at supply to the Consumer Unit (why it isn't 30mA I don't know). The consumer unit in this case is old (and may not actually be a consumer unit - I am not sure of the correct terminology) it doesn't contain RCDs - they look like RCDs but just break on current rather than earth fault.
The fault occurs on main failure (which my AMF panel can simulate). The generator starts up, stabilising for maybe 10 seconds and then the contactors switch over to generator supply. When this happens one of 4 situations occurs:
1. It all works as it should
2. RCD at gen trips
3. RCD at CU trips
4. Both CU & gen RCD trip
Some things I have noticed when trying to trouble shoot:
1. It isn't load related. There must be some load (it I turn all the breakers to off the fault never occurs), if I leave just one or two low current circuits operational then the frequency of RCD tripping remains the same as if full load.
2. I don't think there is an earth leak as once the RCDs trip and I flick them back on there is no recurrence of the problem.
I am now lost as to how I can trouble shoot further. I am not qualified as an electrician but have a reasonable understanding of electronic engineering. I don't particularly want to do this myself but I have struggled to find an electrician that can help.
I've seen a very similar thread here but couldn't find it a second time round for some reason - similar issue to what I have was discussed, alas with no actual diagnosis of problem.
So if I can get any indication of what to try next here that would be a huge help! Thanks.
I am a house owner with a 10Kva stand-by generator (40Amp / single phase). I had the generator professionally installed by my local electrician but I supplied the Automatic Mains Failure switch and generator.
The set-up works perfectly with one issue - there RCDs trip. Given that the backup is supposed to be fail-safe this is far from ideal. The electricians that carried out the install have never worked with this type of equipment before so are not able to support the problem.
The generator is spiked to earth. The utility supply is PME. The PME earth is permanently connected to the generator earth spike so I believe the earth should be common to both generator supply and utility. There is no switching of earths.
The generator supplies the AMF panel through a 100mA RCD located at the generator.
The house is protected by a 100mA RCD at supply to the Consumer Unit (why it isn't 30mA I don't know). The consumer unit in this case is old (and may not actually be a consumer unit - I am not sure of the correct terminology) it doesn't contain RCDs - they look like RCDs but just break on current rather than earth fault.
The fault occurs on main failure (which my AMF panel can simulate). The generator starts up, stabilising for maybe 10 seconds and then the contactors switch over to generator supply. When this happens one of 4 situations occurs:
1. It all works as it should
2. RCD at gen trips
3. RCD at CU trips
4. Both CU & gen RCD trip
Some things I have noticed when trying to trouble shoot:
1. It isn't load related. There must be some load (it I turn all the breakers to off the fault never occurs), if I leave just one or two low current circuits operational then the frequency of RCD tripping remains the same as if full load.
2. I don't think there is an earth leak as once the RCDs trip and I flick them back on there is no recurrence of the problem.
I am now lost as to how I can trouble shoot further. I am not qualified as an electrician but have a reasonable understanding of electronic engineering. I don't particularly want to do this myself but I have struggled to find an electrician that can help.
I've seen a very similar thread here but couldn't find it a second time round for some reason - similar issue to what I have was discussed, alas with no actual diagnosis of problem.
So if I can get any indication of what to try next here that would be a huge help! Thanks.