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)

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.

Quote:

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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".

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"IR" I assume means "insulation resistance," typically measured between leads of the cable, or between a lead and shield (if there is one).

Quote:

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Originally Posted by tkrussell

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

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I think he probably means 7.2 Kvdc, although that would seem to exceed the rating of the cable?