Insulation Resistance Test Transformer

Insulation resistance is the ratio of the applied voltage dc to the total leakage current.

Insulation resistance test transformer.

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. Megger insulation resistance test device. 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. Isolation required for the test.

Turns ratio test 8. Overall power factor and capacitance 2. Pf 5 0 for dry type distribution transformers chl insulation pf tip up for dry type insulation should be 1 0 note. September 5 7 2018 1.

Values based on ieee std 43 2013. Figure 1 test connections for insulation resistance of a single phase transformer. How significant is insulation resistance testing. If the corrected field test values are one half or more of the factory insulation readings or 1000 mω whichever is less the transformer insulation system is considered safe for a hi pot test.

B kv is the rated machine terminal to terminal voltage. 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. Since 80 of electrical maintenance and testing involves evaluating insulation integrity the answer is very important electrical insulation starts to age as soon as it s made. Ansi neta mts 2015 table 100 11 insulation resistance test values rotating machinery for one minute at 40 c.

Leakage current should be as small as possible therby ir value should be as high as possible r v i. And aging deteriorates its performance. The megger insulation tester is a small portable instrument that gives you a direct reading of insulation resistance in ohms or megohms. Insulation resistance decreases in temperature or moisture.