Insulation Resistance Test Transformer

Insulation resistance decreases in temperature or moisture.

Insulation resistance test transformer.

Leakage current should be as small as possible therby ir value should be as high as possible r v i. 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. 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. Values based on ieee std 43 2013.

Bushing power factor and capacitance. Turns ratio test 8. Megger insulation resistance test device. Insulation resistance is the ratio of the applied voltage dc to the total leakage current.

Pf 5 0 for dry type distribution transformers chl insulation pf tip up for dry type insulation should be 1 0 note. 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. The megger insulation tester is a small portable instrument that gives you a direct reading of insulation resistance in ohms or megohms. 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.

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. 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. September 5 7 2018 1. Figure 1 test connections for insulation resistance of a single phase transformer.

How significant is insulation resistance testing. The insulation resistance test is of value for future comparison and also for determining if the transformer is to be subjected to the applied voltage test the winding insulation resistance test is a dc high voltage test used to determine the dryness of winding insulation system the test measures the insulation resistance from individual windings to. And aging deteriorates its performance. B kv is the rated machine terminal to terminal voltage.