Insulation Level of a Current Transfromer

[CuriousElectron]

Greetings,
If a donut type CT is installed over an insulated 13.2kV bus bar, can this CT have insulation level of 0.6kV? I'm trying to understand how do I correlate the insulation level rating of the CT to the insulation rating of the hand wrapped insulation on the bus bar.
Are there any standards that govern this?

Thank you,
EE

 

[RRaghunath]

No.
The CT should be insulated to 13.2kV if it is to be mounted on 13.2kV busbar.
Further, the CT shall have shield which is connected to the busbar to bridge the air space between the CT inner ring and the busbar. This is to avoid voltage grading / partial discharge issues between air and epoxy insulation.
The insulation wrapped around the busbars is not fully rated if I understand right.

 

[CuriousElectron]

I believe the insulation is rated for 13.2kV voltage level.
Regards,
EE

 

[RRaghunath]

EE
"I believe the insulation is rated for 13.2kV voltage level."
If it were to be true, the busbars would not require support insulators. Don't you have them in your switchgear??
You may also check the technical / O&M manual that came with the switchgear or speak to the OEM.

 

[cranky108]

0.6kV rated CT's can be used over insulated cable, as long as the cable has the shield pulled back.

The only reason we use support insulators, is because they have a nice shape and formed ties to hold the cable.
Some older gear have a steel bracket for holding the cables, but the new stuff have support insulators.

0.6kV is the 600 V that the CT can create when it is open circuited.

Notice that I said insulated cables, and not bear conductors.