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Outer Sheath MV cable DC test

Outer Sheath MV cable DC test

Outer Sheath MV cable DC test

(OP)
Hello!

I'm performing DC test to verify the outer sheath integrity on a MV 36kV cable after laying, according to IEC 60840 & IEC 60229 standards. I'm using a BAUR testing equipment. According to the manufacter, the test equipment negative (-) terminal should be connected in the outer sheath and the positive (+) terminal in the earth (ground). Both cable ends should de disconnected from earth. My question is, if I connect the positive terminal (+) in the sheath and the negative terminal (-) in the earth the test will not work?

Thanks in advanced.

RE: Outer Sheath MV cable DC test

(OP)
I've been thinking about my own question. Perhaps if I connect the negative terminal (-) of the DC source in the earth and the positive terminal (+) in the cable sheath, and because the electrons flow from the (-) to (+), i'm not be able to detect a defect in the insulation of the cable. Am I correct?

Thanks ;)

RE: Outer Sheath MV cable DC test

For your own safety, please engage the services of someone experienced and competent in cable testing. It is very easy to receive a nasty and potentially fatal electric shock if you don't know what you are doing, which is inferred by the basic nature of your question.
Regards
Marmite

RE: Outer Sheath MV cable DC test

(OP)
Thank you for your wise advice.
Regards

RE: Outer Sheath MV cable DC test

Yeo, should work, look for high Mohm values.

RE: Outer Sheath MV cable DC test

In dielectric testing insulation that is in an air environment we use a positive ground reference. Most DC test sets output a negative DC voltage at the HV test lead, so you really don't have a choice. What is important in cable sheath HV testing is the ampacity of the test set, a simple insulation resistance tester (Megger) is not really suitable for a cable sheath test. The BAUR Shirla is a good example of this type of set.

The only time I used a Negative output test voltage (200 kVdc) was in an oil filled two bushing reactor filter equipment, that was subject to shipping damage. It passed.

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