Protection CT Grounding

[jliu1]

For protective relaying circuit such as transformer differential protection, there are two sets of bushing CT used, on the HV side and LV side. The question is where should the CT be grounded? At the transformer side which is in the transformer control panel or the relay side which could be 200 meters away? What about other protection circuit with only one CT? Thanks a lot in advance.

 

[jghrist]

ANSI/IEEE C57.13.3 recommends that the ground be at the relay panel. This provides maximum protection for personnel and equipment at the relay panel where they are most likely to be exposed to circuit overvoltages.

 

[warsi]

Dear.

For HV side and LV side bct it would be in the relay panel as IEEE standard