AC or DC for Hipot Testing
AC or DC for Hipot Testing
(OP)
I'd like to check our motors with a Hipot test. The field wires are a bit close to the metal housing. The motors are universal and we run them on 115 vac 60 hz. I assume I should use an AC Hipot. When would one use a DC Hipot test?





RE: AC or DC for Hipot Testing
RE: AC or DC for Hipot Testing
New manufactured electrical machines are required to pass a proof Hi-Pot test of;
Vp-ac = 2*Vnom+1000 AC Volts for one minute.
Repetitive test is not recommended, however when necessary 60% of the voltage applied to a new insulation is recommended and never should exceed 85% of the initial test.
DC Voltage Hi-Pot is accepted as equivalent but the value must be increased by 1.7.
Vp-dc = 1.7 x Vp-ac
DC is used to reduce the KVA requirements and allow light high voltage supply of the test equipment. For large machines the circuit has a high capacitive current component, demanding more current and proportionally more kVA during the test.
To verify the insulation condition of a machine an evaluation could be done by measurement of the insulation resistance ( IR ) and the polarization index ( PI ), these taken with a Megohms meter ( Megger). These are not destructive tests.
RE: AC or DC for Hipot Testing
Mike
RE: AC or DC for Hipot Testing
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David Baird
mrbaird@hotmail.com
Sr Controls Engineer
EET degree.
Journeyman Electrician.
RE: AC or DC for Hipot Testing
RE: AC or DC for Hipot Testing
RE: AC or DC for Hipot Testing
Mike
RE: AC or DC for Hipot Testing
RE: AC or DC for Hipot Testing