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    dchan48's Avatar
    dchan48 Posts: 1, Reputation: 1
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    #1

    Jun 20, 2007, 01:30 AM
    Hi Pot testing of HV Cable
    A friend of mine (electrician) has conducted IR and Hi-Pot test on a short length (app. 1 km) of 3.3kV XLPE/SWA/LC/PVC cable. The hi-pot test voltage used was 7.2VDC.

    IR of one of the phases dropped from 200Gohm (before hi-pot) to 18Gohm
    (after hi-pot). The IR for the other phases also dropped by around
    30-100Gohms.
    The next day he tested the same phase (after cleaning the
    terminations with solvent) and the value had gone up to 170+Gohm.

    Are the results reasonable? Why was the marked changed in IR (measured by 1kV Megger tester)
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
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    #2

    Jun 20, 2007, 03:04 AM
    What does IR stand for? I take IR as Infrared Imaging. I am not sure of the context you are using "IR".

    Only 7.2 VDC? My Hi Pot, ( High Potential) injects 10000- 60000 volts.

    Any HI-Pot voltage testing needs to exceed the voltage rating of the cable for a n accurate test.

    In any case, cleaning the terminations usually reduces resistance.

    Also, be sure to note the relative humidity, of course, this is a concern with the type of Hi -Pot testing I do.

    A standard Megger is not an appropriate instrument for this type of cable testing.
    ebaines's Avatar
    ebaines Posts: 12,131, Reputation: 1307
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    #3

    Jun 20, 2007, 09:35 AM
    Quote Originally Posted by tkrussell
    What does IR stand for? I take IR as Infrared Imaging. I am not sure of the context you are using "IR".
    "IR" I assume means "insulation resistance," typically measured between leads of the cable, or between a lead and shield (if there is one).

    Quote Originally Posted by tkrussell
    Only 7.2 VDC? My Hi Pot, ( High Potential) injects 10000- 60000 volts.
    I think he probably means 7.2 Kvdc, although that would seem to exceed the rating of the cable?

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