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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
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  • 0

    seko:




    sparkiemike:




    Sparkingchip:

    Is it actually doing a ramp test?




    Don't think so, I think is the RCD tripping time because in the image the results on the instrument are in milliseconds


     




    It is failing the test that is shown as ">1500 mA" on the display. This is a "trip-out current test" (see: Metrel 3152 manual, page 108) The "trip-out test" is described as: "The instrument increases the test current in small steps through appropriate range as follows" see page: 107.


    The test stops at 1500 mA, and the test fails


     




    I’m used to seeing ramp test results displayed to one decimal point such as in the Metrel manual example as 25.5 mA for an 30 mA RCD, but stopping to think about it small increments in the test current for an 1000 mA RCD could be 10 mA or more so the test results could be displayed in substantial incremental steps increasing the chances of the trip current being displayed as 1000 mA significantly, when it could be a bit off that.


    I wonder how many increments there are between 1000 mA and 1500 mA when it fails the test, could it be going up in 100 mA steps or more?


    If there’s another tester to hand it could be worth doing another RCD ramp test to try and pin down what the actual trip currents are a bit more precisely.


    Andy 

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  • 0

    seko:




    sparkiemike:




    Sparkingchip:

    Is it actually doing a ramp test?




    Don't think so, I think is the RCD tripping time because in the image the results on the instrument are in milliseconds


     




    It is failing the test that is shown as ">1500 mA" on the display. This is a "trip-out current test" (see: Metrel 3152 manual, page 108) The "trip-out test" is described as: "The instrument increases the test current in small steps through appropriate range as follows" see page: 107.


    The test stops at 1500 mA, and the test fails


     




    I’m used to seeing ramp test results displayed to one decimal point such as in the Metrel manual example as 25.5 mA for an 30 mA RCD, but stopping to think about it small increments in the test current for an 1000 mA RCD could be 10 mA or more so the test results could be displayed in substantial incremental steps increasing the chances of the trip current being displayed as 1000 mA significantly, when it could be a bit off that.


    I wonder how many increments there are between 1000 mA and 1500 mA when it fails the test, could it be going up in 100 mA steps or more?


    If there’s another tester to hand it could be worth doing another RCD ramp test to try and pin down what the actual trip currents are a bit more precisely.


    Andy 

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