We have talked before about the method of measuring the insulation resistance and absorption ratio of the winding, and the method of measuring the DC resistance of the winding; Senli Motor Xiaobian today will briefly explain to you the DC voltage resistance test of three-phase asynchronous motor stator windings, and the method of leakage current measurement and related precautions.
We need to dismantle it firstThree-phase asynchronous motorThe neutral point is connected to make the spacing of each phase output line meet the requirements of experimental voltage.
The DC voltage withstand test must be carried out in separate phases, and the test voltage is the rated voltage of the stator winding3Times when testing by each stage0.5Multiple rated voltages rise in stages and stay at each stage1minHere to do a good job of recording its leakage current, leakage current should not increase with time.
The leakage current should be recorded step by step, and the difference between phases of the leakage current should not be greater than the minimum value under the specified voltage100%When the maximum leakage current is20There should be no obvious difference between phases when the temperature is below microampere.
If the leakage current is out-of-phase during the test, the microammeter swings greatly, and the leakage current rises sharply with the rising voltage pool, accompanied by discharge sound, we should stop the operation test to find out the reason. Distinguish whether there is a problem between the test loop and the winding under test. If the winding is inter-problem, the discharge part should be checked The insulation is faulty.
Three-phase asynchronous motor manufacturersRemind that when the casing is not connected to the shielding line or the shielding line is in poor contact with the casing, the shielding effect is not good, and the shielding line should be connected and made in good contact; The test should be carried out when the power supply voltage is stable, so as not to cause leakage current fluctuation; The ripple coefficient of DC generator used should meet the requirements; Finally, this type of project is a high pressure test, the test should comply with the relevant regulations, pay attention to the safety of the person and the tested equipment.
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