Hi-pot testing vs. meggering
Hi-pot testing vs. meggering
(OP)
Could someone briefly explain to me the difference between meggering and hi-pot testing of cables? I know that meggering involves placing a DC current, usually no more than 2 times the rated AC voltage, between the cable and ground to test the insulation resistance.
Hi-pot testing involves a much larger voltage I know, but I'm confused as to what you're looking for. Is it leakage current? Either way, aren't you basically looking for the same result (insulation resistance)?
Thanks in advance.
Hi-pot testing involves a much larger voltage I know, but I'm confused as to what you're looking for. Is it leakage current? Either way, aren't you basically looking for the same result (insulation resistance)?
Thanks in advance.






RE: Hi-pot testing vs. meggering
RE: Hi-pot testing vs. meggering
Only if the resistance is perfectly linear.
As voltage is increased there may be partial discharge or breakdown.
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RE: Hi-pot testing vs. meggering
Hi-pot (AC or DC), a potentially destructive test, tests the dielectric strength of the cables i.e the ability withstand rated and higher than rated voltages that are experienced during the operation.
While a high megger value doesn't necessarily indicate the dielectric strength (the ability to withstand high voltages), a low megger value (which is normal in cables)doesn't necessarily mean that the cables will fail the hi-pot test. I have seen cables with excellent megger values fail the hi-pot while their poorer cousins taking it on the chin comfortably.
So, meggering and hi-pot are not one and the same.
RE: Hi-pot testing vs. meggering
A Hipot has continually adjustable voltages up to 80kV and above, and the results are in microamps(leakage).
Both instruments are used to check the quality of insulation.
The Megger test is usually non-destructive because the voltage levels used are at or below the equipment ratings, while the Hipot tests are usually destructive, for the opposite reason.