Current Transformer

[vtand]

Hello I'm new to this board. My question is:
1)Is there any PM(Preventive maint) to be carried out on current transformers?
2)Why CT explode? Possible reasons?
Appreaciate your inputs. Thanks

 

[RRaghunath]

If you are talking of CTs with oil impregnated paper insulated windings, periodic testing of tan delta will tell you the health of the insulation.

Conducting the knee point voltage test for PS class CTs, occassionally, is another one.

When it comes to the question, why CTs explode, I think the most likely cause is open circuiting of CT secondary wiring. This can give rise to high voltage spikes across the CT secondary winding.

I have also seen failure of CTs (24kV class) with solid insulation and a shield (as part of insulation coordination). The suspected cause was loose wiring in connection shield - to - the primary conductor.

 

[vtand]

Rraghunath, Thank you very much for your quick response,

 

[buzzp]

In addition to the other comments, burden tests are often performed but would not have anything to do with exploding (unless the burden was so high to be an open circuit as rrag suggests). I have never heard of a typical CT exploding. The new techology ones (sorry cant recall the terminology), I have heard of exploding, the optical CTs.

To be honest, I don't know how an open circuit on the CT leads could cause a CT to explode either. Sure the insulation breaks down and causes a short somewhere in the CT but this should not cause a CT to come apart.