Morteza2
Electrical
- Apr 19, 2012
- 11
Dear all,
We have an application where we are installing low voltage CTs on a medium voltage system.
The CTs will be installed on insulated cables on the secondary of a transformer, that is operating at 5kV.
As you are aware, it is fine to use LV CTs on MV systems as long as the system has proper insulation and the CTs are not close to any exposed terminals.
Here’s the precaution that the manufacturer recommends:
“Where a low voltage window type CT is intended for use in a higher voltage application, it is the purchaser’s responsibility to ensure the operating conditions are met and the necessary precautions are taken. This is usually verified by performing insulation tests at an appropriate level of system voltage with the low voltage current transformers installed. “
I wanted to seek your opinion on what you think would be an appropriate ‘insulation test’ for this configuration.
Would a megger test on the secondary of the transformer with test voltage defined as per NETA requirements be adequate? Or perhaps a DC or AC hipot test? My concern with the AC hipot test is that it would be damaging to the transformer, as I recall based on a conversation I had once with a transformer manufacturer.
Would appreciate your input.
Thank you
We have an application where we are installing low voltage CTs on a medium voltage system.
The CTs will be installed on insulated cables on the secondary of a transformer, that is operating at 5kV.
As you are aware, it is fine to use LV CTs on MV systems as long as the system has proper insulation and the CTs are not close to any exposed terminals.
Here’s the precaution that the manufacturer recommends:
“Where a low voltage window type CT is intended for use in a higher voltage application, it is the purchaser’s responsibility to ensure the operating conditions are met and the necessary precautions are taken. This is usually verified by performing insulation tests at an appropriate level of system voltage with the low voltage current transformers installed. “
I wanted to seek your opinion on what you think would be an appropriate ‘insulation test’ for this configuration.
Would a megger test on the secondary of the transformer with test voltage defined as per NETA requirements be adequate? Or perhaps a DC or AC hipot test? My concern with the AC hipot test is that it would be damaging to the transformer, as I recall based on a conversation I had once with a transformer manufacturer.
Would appreciate your input.
Thank you