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Type B time delayed rcd

Baldyhugh
Hi


As part of a job I’m currently on I have connected a single phase supply to a Danfoss variable speed inverter drive. I wasn’t aware that this would be part of the job but there you go. Anyway I connected it and powered it up and a few seconds later it tripped the rcd. I informed the installers of the drive incase it was faulty but they said that it’s probably the wrong type of rcd. I researched the spec of the drive which says that I need a type B time delayed rcd. I spoke to Hager technical dept as these are the boards I have used and they said that they only do a 4 pole B type but not time delayed. There is an A type time delayed available which is double pole but they didn’t think that it would work as it doesn’t monitor dc which the B type does. These different types are new to me so would anyone have experience of them to offer some advice?


Thanks
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    Several years ago when I was working with those RCDs the upfront 100mA Time delayed RCD was tripped by an inverter, but the downstream 30 mA RCD didn’t trip, presumably because it was being blinded, I have had the same again with Bosch direct drive washing machine in a different house.



    Possibly not blinding as such, but maybe just lack of sensitivity to some waveforms. If the "leakage" was pulsed d.c. say - an A-type 100mA should trip, but a downstream AC-type 30mA is permitted to ignore it. Even if both were AC types it might just happen that one still has some sensitivity to pulsed d.c.


       - Andy.
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    Several years ago when I was working with those RCDs the upfront 100mA Time delayed RCD was tripped by an inverter, but the downstream 30 mA RCD didn’t trip, presumably because it was being blinded, I have had the same again with Bosch direct drive washing machine in a different house.



    Possibly not blinding as such, but maybe just lack of sensitivity to some waveforms. If the "leakage" was pulsed d.c. say - an A-type 100mA should trip, but a downstream AC-type 30mA is permitted to ignore it. Even if both were AC types it might just happen that one still has some sensitivity to pulsed d.c.


       - Andy.
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