Values based on ieee std 43 2013.
Insulation resistance test standard for transformer.
The transformer neutral bushing is to be disconnected from earth during the test.
With a little record keeping and common sense however you can get a good picture of the insulation condition from values that are only relative.
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Adjust megger tester at 1000 v dc.
The transformer neutral bushing is to be disconnected from earth during the test.
Value at 60 seconds after application of the test voltage is referred to as the insulation resistance of the transformer at the test temperature.
The test is performed with a power factor test kit and the connections are the same as for the megger test the insulation resistance test.
Apply the test voltage and note the reading.
Insulation resistance decreases in temperature or moisture.
The megger insulation tester is a small portable instrument that gives you a direct reading of insulation resistance in ohms or megohms.
A rated line to line voltage for three phase ac machines line to ground voltage for single phase machines and rated direct voltage for dc machines or field windings.
Isolation required for the test.
Insulation resistance is the ratio of the applied voltage dc to the total leakage current.
Clean the terminals of the transformer.
B kv is the rated machine terminal to terminal voltage.
Steps of this test.
Value at 60 seconds after application of the test voltage is referred to as the insulation resistance of the transformer at the test temperature.
Insulation resistance test of transformer is divided into three parts.
This test can be repeated during the service life of the transformer and verified against the result obtained during manufacturing as a check to determine if the insulation is malfunctioning or decaying.
Apply the test voltage and note the reading.
