Insulation Resistance Test Transformer

September 5 7 2018 1.

Insulation resistance test transformer.

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. The megger insulation tester is a small portable instrument that gives you a direct reading of insulation resistance in ohms or megohms. Values based on ieee std 43 2013. And aging deteriorates its performance.

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. How significant is insulation resistance testing. Megger insulation resistance test device. 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 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. Insulation resistance decreases in temperature or moisture. 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. Turns ratio test 8.

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. Pf 5 0 for dry type distribution transformers chl insulation pf tip up for dry type insulation should be 1 0 note. Overall power factor and capacitance 2. Figure 1 test connections for insulation resistance of a single phase transformer.

Ansi neta mts 2015 table 100 11 insulation resistance test values rotating machinery for one minute at 40 c. 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. Isolation required for the test. Bushing power factor and capacitance.