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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
  • 0
    Beyond my pay grade, but I’ll ask a question.


    Why does it need to be time delayed if there is not another RCD with a lower rating downstream of it?


    Andy Betteridge
  • 0
    Why do you have an RCD at all?
  • 0
    Andy


    I don’t know, it’s what the spec of the equipment says. I’m thinking of calling the manufacturer tomorrow to see if there is any more info that they can give me before I splash out on an rcd which may not cure the problem
  • 0
    Dave


    It’s a farm so rcd protection on all circuits
  • 0
    A B-type should trip on everything an A type should trip on - plus it'll also trip on pure d.c. leakage.


    Likewise a A type should trip on everything an AC type should trip on - plus pulsing d.c.


    So changing to a B-type of itself isn't likely to solve an 'unwanted tripping' situation.


    Changing from a non-delayed to delayed might help - in that the equipment might be producing short bursts of leakage beyond normal limits - which a time delayed unit might ignore, but an instantaneous one respond to.


       - Andy.
  • 0
    Any reason why you cannot try a 300 mA Type A RCD?


    Andy Betteridge
  • 0
    I have sent you a couple of links for RCDs cheap enough just to try them.


    Andy B.
  • 0
    Out of interest I looked at some installation instructions for one of the product range, not over helpful are they?


    The earth fault protection inside the frequency converter protects only the converter itself against earth faults.

    If fault current protective switches are used they must be tested with the drive with earth fault currents that are possible to arise in fault situations.


    Andy B
  • 0
    Hi Andy 


    that’s what I probably will do but was just looking a bit of advice from others before I try one as I’m not too familiar with the type A and B and their uses
  • 0
    This is one of those occasions when detailed installation instructions are really required, without getting the equipment up and running you cannot take any measurements to determine what leakage there is under normal conditions.


    Before you know where you are you can spend quite a bit of time trying to fix an issue that isn’t really yours.


    Andy Betteridge

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