Hi Potting Motor Cables

[rockman7892]

When Hi-Potting new motor cables (5kV cables)what is the general rule for acceptance criteria. I know the leakage current depends on a number of factors including cable length, but is there a general rule of thumb for acceptance values on new cable?

The voltage is being applied in 1 min incriments until a maximum test voltage of 25kV DC is reached and held for 15min.

Is it necessarily the leakage values that are important, or is it the graph of the leakage current vs voltage for step incriments (should be linear) and leakage current vs time for the fianl voltage (should be steady) that is important?

 

[Zogzog]

You are right, it is all about the shape of the plot, not so much the values. Hipot is basically a go-no -go test which is why it isnt that good of a test, better off with a Tan Delta test, that way you have some meaningful test results.

 

[rockman7892]

Zogzog

When you say a go-no-go test are you referring to the Hi-Pot tripping if something is wrong, or the shape of the curve determining the go-no-go scenario?

 

[Zogzog]

Both, if you see current increasing you should stop the test before the unit trips