What is the purpose of HV / leakage current test on stator?

What is the purpose of HV / leakage current test on stator?  
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1 Answer

Answer :

This is to find out weakness in the stator winding. If the ambient conditions are right, and the insulation is weak, the leakage current will increase non-linearly. 

The record of voltage versus leakage current provides the condition of the winding for present and future use and may permit prediction of breakdown voltage whether it is within or slightly above the test voltage. 

HV test voltage = 1.5 * rated voltage for AC

And DC voltage = (2E + 1 kV) 1.6

Where E – rated voltage.

1.6 – AC/DC conversion factor.

Application of HV voltage also depends on the age factor or condition of the machine.

Following are the findings of HV test.

a) Capacitance charging current.

b) Dielectric absorption current.

c) Surface leakage current.

d) Partial discharge current.

e) Volumetric discharge current.

In HV test starting leakage current should be more than switching off current in μ Amps. 

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