Transformer Core Ground to Tank Connection - Adding Resistor To Mitigate Circulating Currents

[rand1234]

Hello, hope everyone's day is going well!

I have a question regarding the transformer core ground to tank connection. I have heard situations where adding a resistor to the transformer core ground to tank connection mitigates circulating current issues for cores that have unintentional 2nd or multiple ground issues. Does anyone have any information or resources on how the resistor sizing (wattage and resistance) is done for situations like this?

 

[stevenal]

We went back to the transformer manufacturer. The transformer was not manufactured with an external core ground bushing, so the manufacturer provided the bushing in a man hole cover, and the proper resistor. Our transformer spec now includes core ground bushings.

We think the unintentional core ground is now fixed, and we may be removing the resistor.

As I recall, Doble had some information on this subject.