Continuous Sensing of Partial Discharge on 11KV Cables, Connected in Ring Circuit

A quick Google search on "partial discharge monitoring" produces half a dozen likely suppliers of systems that do what you are asking. Why not try contacting some of them?

These guys make and sell the systems....

http://www.martec.co.za

Informative paper on methodology....

click here...

The ability to detect leakage is possible and some offerings for equipment to detect this are available with varying advantages and disadvantages for each type. You will have to get fairly involved with each technology and approach to make a decision as to which works best for your system.

I would like to address the idea of DC hipot for this type of cable however. We did a lot of it for customers when I was still working and the statistical data that we accumulated said that the customers who did it had more failures of cables than those that did not. While it is claimed to be non-destructive testing, it has a cumulative effect of lowering the life of the cable. We had a few customers who allowed us to use power factor testing of the cable insulation which was able to detect the leakage current and capacitance change in the cable and subject the cable to only a few percent above rated voltage AC rather than DC. We could see the approach of aging on the cable and predict when the cable needed replacement a few years before failure occurred. Customers that used power factor testing had far fewer emergency cable failures than those that used DC Hipot. I was personally convinced that DC hipot contributed to the failure of this type of cable even though the use of DC hipot is the industry standard for the the testing and cable industry.

i was also wondering why it makes sense to do DC hipot testing on cables normally used for AC? and why DC testing would contribute to accelerated failures?

In my opinion your cables are fabricated following IEC 60502-2.In Ch.20 Electrical tests after installation

no partial discharge is mentioned. Only

20.1 D.C. voltage test of the oversheath and

20.2 Insulation test.

However, there are some remarks:

NOTE 1 A d.c. test may endanger the insulation system under test. Other test methods are under consideration.

NOTE 2 For installations which have been in use, lower voltages and/or shorter durations may be used. Values should be negotiated, taking into account the age, environment, history of breakdowns and the purpose of carrying.

So why to carry a such dangerous test for cables still operating?.