Hi Pot Test of metalclad switchgear

[uts123]

Dear All,

I have seen during hi pot test of switchgear, PT takes out of circuit. So PT won't subjected to Hi potential test.
But in actual sevice condition, PT will be in circuit and exposed to hi voltage like other component during abnormal condition.

Please reply.

 

[Marmite]

Yes. So what's the question?
If the PT isn't rated for the test voltage you are using for the switchgear, then test it at a suitably reduced voltage that it is rated for.
Regards
Marmite

 

[uts123]

Thank you Marmime.

I got answer.

Hope same time of help in future.

UTS123

 

[Zogzog]

PT's are removed during hipot test becasue they would prevent you from being able to get to test voltage and mess up the test, not to prevent damage to the PT.

 

[RRaghunath]

PTs are transformers essentially and if PTs are in circuit during hipot, the frequency of the voltage applied has to be increased to ensure the flux magnitude (V/f) is till within design limits for the PT core.
This is often not convenient and hence PTs are tested separately.

 

[davidbeach]

More importantly, VTs are a deliberate impedance between phase and ground or between phase and phase. A hipot is a test to verify lack of connection between phase and ground or between phase and phase. With the VT in the circuit, there is a fixed maximum impedance to be measured and the VT will bleed off the hipot voltage as fast as it is applied.

 

[slavag]

What David saied!!!!