Extech Instruments MG500 Manuel d'utilisateur télécharger pdf (Page 12)

MG500-EU-EN v1.0 7/13

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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

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Extech Instruments MG500 Manuel d'utilisateur Page 12