User's Manual

MG500-EU-EN v1.0 7/13
12
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TransformerTesting
Transformer tests are performed with the transformer completely disconnected from the line
andtheload.Notethatthecasegroundshouldnotberemoved.
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Thefive tests listed belowwill completely test a single‐phase transformer. Notethat at least 1
minuteshouldbeallowedbetweeneachtest.
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1. High
voltagewindingtolowvoltage
windingandground
2. Lowvoltagewindingtohighvoltage
windingandground
3. Highvoltagewindingtolowvoltage
winding(picturedatright)
4. Highvoltagewindingtoground
5. Lowvoltagewindingtoground
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NotesonMeasuringtheResistanceofaContactororCircuitbreaker
AContactororCircuitbreakermustprovidealowresistancepathtoelectricitywhenclosedbut
shouldprovideahighresistancewhenopen.Astheyage,theircharacteristicsmaydeteriorate
becauseofheavyuse,operationinadirtyenvironment,orotherfactors.
UnusualInsulationResistanceMeasurementApplications
o Specialpaintorvarnishmaybeusedasaninsulatorontransformersandotherelectrical
applications
o Insulatingblankets,suitsandglovescanalsobetested
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Connect the
GREEN lead here
Connect the
RED lead here