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Type-A RCD failing 180 degree ramp test

Former Community Member
Former Community Member
Hi


We are testing a type-A RCD (see image: "ABB") with a METREL MI 3152 (see image: "MI 3152 test").

As the image shows, the ramp test (I delta) is failing to trip the RCD for the negative half wave.


Have oneone seen this before?


Br Sebastian
attachments.zip
  • Former Community Member
    0 Former Community Member

    WB³:




    seko:




    WB³:




    seko:



    We have tested other RCDs of this type that have passed, but it seems to only be related to this specific installation type. 



     




    Hi seko, could you clarify if you mean it is related to this specific installation, or it has happened before on this type of installation?


    Is it a new installation verification or an EICR or another purpose?


     




    It has happened before "on this type of installation". It is a new installation. 


     




    Thanks for the reply, my suggestion although I haven't ever ramp tested an RCD would be to try repeating the tests in manual mode rather than automatic, it might be that the RCD gubbins gets a bit too warm after closely repeated operations?


     




    Hi Seko, going back to the previous installations where you have had this happen before, how was it resolved, and is there a particular reason you are carrying out the ramp tests such as its part of a specification or because the tester does it automatically?


    Out of interest as would reversing the polarity of the supply of the device under test conditions show the other way round on your scope, ie would the device fail the ramp test on the positive mode rather than negative? Ps thanks for the great pics diagram graphs etc, it's great to see the forums capabilities being used to good effect :)

  • Former Community Member
    0 Former Community Member

    mapj1:

    looks faulty to me.  Very Surprising though.




    The most surprising part is that test "6" and "2" are similar (waveform) at one point during test "6" - and test "2" doesn't fail (see: "2" and "2-1").

     

    attachments.zip
  • Former Community Member
    0 Former Community Member

    WB³:




    WB³:




    seko:




    WB³:




    seko:



    We have tested other RCDs of this type that have passed, but it seems to only be related to this specific installation type. 



     




    Hi seko, could you clarify if you mean it is related to this specific installation, or it has happened before on this type of installation?


    Is it a new installation verification or an EICR or another purpose?


     




    It has happened before "on this type of installation". It is a new installation. 


     




    Thanks for the reply, my suggestion although I haven't ever ramp tested an RCD would be to try repeating the tests in manual mode rather than automatic, it might be that the RCD gubbins gets a bit too warm after closely repeated operations?


     




    Hi Seko, going back to the previous installations where you have had this happen before, how was it resolved, and is there a particular reason you are carrying out the ramp tests such as its part of a specification or because the tester does it automatically?


    Out of interest as would reversing the polarity of the supply of the device under test conditions show the other way round on your scope, ie would the device fail the ramp test on the positive mode rather than negative? Ps thanks for the great pics diagram graphs etc, it's great to see the forums capabilities being used to good effect :)


     




    Hi. It has been resolved with replacement, but now we see new devices with the same behavior. I am not entirely sure who defined the test procedure. When doing the "required" test the external company has programmed the tester to go through all the tests automatically. 

  • Former Community Member
    0 Former Community Member
    Does anyone know if the ramp test is even "required" for European/Danish standards?
  • 0
    One outcome of this discussion is that I bought a new multifunction tester this week and got myself a Megger MFT1741 rather than a Metrel.
  • Former Community Member
    0 Former Community Member

    seko:

    Does anyone know if the ramp test is even "required" for European/Danish standards?




    Hi Seko, if it's any help it's not a BS7671 certification requirement. From what I can gather the ramp test is most often used to identify a device that has become over sensitive in an existing installation rather than the commisioning of a new device.

  • Former Community Member
    0 Former Community Member
    Hi


    I think that I found the reason for the faulty RCD (see: "RCD.jpg") :)

    -In front of my eyes all this time


    Sebastian


  • 0
    I looked at this last night, both moulded cases look identical, but the labels are mis-matched. I am assuming the iffy RCD is the top one and the label lacks the professional looking finish to the lower one and there isn’t the same amount of information.


    Looking at the label on the top RCD I would question its provenance, but I am not picking anything up in particular on “Made in Italy” being highlighted.


    Andy
  • 0
    My wife has just tried the spot the difference competition and agrees the moulded cases look near enough identical, but agrees the label on the top RCD has the appearance of less than perfect scan and print when compared with the lower RCD.


    Andy

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