Core Ground Test

[pablo r. reyes]

I need a clear explanation about Core Ground Test on transformer. As I know, transformer core is insulated from the tank and other grounded parts. If an inadvertent ground occurs, a circulating current path is created that could damage the core. My question is, if we are avoiding inadvertent ground on transformer core, then why the transformer core is grounded by a single strap?

 

[rcwilson]

Re: Core Ground Test

A single point ground prevents the core from floating to some unknown voltage which could cause winding insulation problems. It also drains any static charges and provides a fault current path when a winding fails.

With only one connection, the core has all the benefits of keeping metal at ground or case potential wihtout the problems of circulating currents.