33kV cable problem

What type of protection you have? What relay operates when it trips?

Did you meggar between each of the core of the cables and between each core and earthing (grounding)?

The meggar value you indicated is low but it is not that bad.

- MS

what are the things connected your VCB out put side,[i think pt,ct,and transformer]

isolate one by one and megger the cable and find out the value,otherwise disconnect the vcb out going cable anther end and check the cable,if cable is ok and then check other connected things, finely transformer bushings and transformer winding.

anand ck

Some more inputs are required.

1) After you close your side ,utility side vcb trips-OK did you try to close utility VCB-what is happening?

2) The utility VCB trips under what fault-UV/OV/OC/EF can you inform us?

3) Is your VCB connected to a transformer ,if so what is the rating of the trasformer and what are settings of protective relays

4) does trippings take place repeatedly or now only ?

A Hipot megohmeter with a full wave bridge will give you an approximate location. An Underground Cable Fault Locater used by power companies progressively burns out the fault using high amperage. This is then followed with a high voltage capacitor discharge. The result of all this expensive hardware is something like the report from a pistol shot. Use a stethascope to find the exact location.

Batteries not included.

You also need to check if there is any synchronisation or out of phase issue. A simple phase rotation check is often forgotten.

If you are trying to parrallel 2 transformers or feed one transformer from another you need to study the circuitry to ensure you have not created the problem by the way it is set up eg an earth point at one end that is seen as a fault by the relay at the source end.

I also agree that checking your protection scheme is a good idea as there may be a fundamental error in how it is set up.

If it is a cable problem the OMNICRON & BAUER have instruments that can detect the cable fault & give an estimate of where the fault is along the cable length. However, my experience is that if it is a newer installation then start looking at the cable terminations & connections first, human error is often a source of problems.

i think your cable is ok you shold check all wiring dig of your vcb