Field testing of CT's in SF6 switchgear
Field testing of CT's in SF6 switchgear
(OP)
We received an enquiry for commissioning of 110 kV GIS. Unfortunately we have no experience in field testing of CT's in such switchgears. Would you suggest me which parameters are usually tested ?
According to me they should be Insulation resistance measuring of secondary windings and possibly Excitation curves. Insulation resistance from primary winding and Primary current injection tests seems not to be applicable for that case.
Of course we will ask the manufacturer, but for the moment some advice from experienced colleagues will be very helpful.
According to me they should be Insulation resistance measuring of secondary windings and possibly Excitation curves. Insulation resistance from primary winding and Primary current injection tests seems not to be applicable for that case.
Of course we will ask the manufacturer, but for the moment some advice from experienced colleagues will be very helpful.
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It may be like this in theory and practice, but in real life it is completely different.
The favourite sentence of my army sergeant






RE: Field testing of CT's in SF6 switchgear
RE: Field testing of CT's in SF6 switchgear
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For conventional CT's is OK, but for these in GIS probably there is no access to primary winding terminals, so how about polarity and ratio ?
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It may be like this in theory and practice, but in real life it is completely different.
The favourite sentence of my army sergeant
RE: Field testing of CT's in SF6 switchgear
RE: Field testing of CT's in SF6 switchgear
old field guy
RE: Field testing of CT's in SF6 switchgear
By the way, with 26-years commissioning of 6 to 400 kV substations on three continents can I join also the club of Old Field Guys
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It may be like this in theory and practice, but in real life it is completely different.
The favourite sentence of my army sergeant
RE: Field testing of CT's in SF6 switchgear
RE: Field testing of CT's in SF6 switchgear
Have a look at your earthing switches. Depending on configuration they can provide a means of getting current on and off the busbar for test purposes. I've used this method before.
Obviously you will need to keep a dead and earthed section of bar between you and anything live - that sometimes limits your options for choosing a switch.
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If we learn from our mistakes I'm getting a great education!
RE: Field testing of CT's in SF6 switchgear
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It may be like this in theory and practice, but in real life it is completely different.
The favourite sentence of my army sergeant
RE: Field testing of CT's in SF6 switchgear
I have done these and ended up string a lot of temporary test conductors between incoming line bushing and such. It's not easy.
The megger test is a point I missed. That needs to be done for sure.
old field guy
RE: Field testing of CT's in SF6 switchgear
73! from LZ5PL
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It may be like this in theory and practice, but in real life it is completely different.
The favourite sentence of my army sergeant
RE: Field testing of CT's in SF6 switchgear
Depending on the bus configuration, you can set up one end on the line side of the main CB and then test through to other breakers.
Using the voltage method would probably be easier, especially for HV gear, as the earth switch connections will be high up. Voltage method uses small leads, vs. current which would be much larger.
Careful planning (test all CT's per phase) can speed up the job.