GIS Testing 2

[SamHans05]

HI everyone good day. Just want to ask regarding the HV test for the GIS having 230kV. My Contractor is telling me that during the HV test they want to take out the Surge arrester and VT. For me, VT is fine that they should not include when there is an HV test but im still confused why they dont like to include the Surge arrester during this test? Is there any very good reason or some standard that Surge arrester is not included in the HV testing?

Hoping for kind reply. Thanks

 

[ScottyUK]

As the test voltage approaches the breakdown voltage of the arrestor the leakage current through the arrestor will increase to the point where it will distort the test results and possibly mask genuine a problem.

 

[Neilie01]

Hi...

IEC 62271-203 2nd Edition the reference for GIS above 52kV.
Quote: Some parts may be disconnected for the test, either because of their high charging current or because of their effect on voltage limitation, such as:
High voltage cables and o/h line;
Power transformers and occasionally voltage transformers;
Surge arresters and protective spark gaps.

From our site procedures:

Surge arresters are also not part of the test and therefore they are not installed or the
particular links have to be removed;
Voltage transformer (VT): secondary windings are open, one side grounded.
Otherwise dangerous high voltages can lead into personal injury or damages the
secondary installations.
VT: Potentially installed ferro resonance circuits are disconnected;
Current transformer (CT): secondary windings are short-circuited. Otherwise
high currents can result considerable damages of the current transformers.

 

[SamHans05]

Thanks for all your reply. Appreciated.