Restricted Earthfault tripping

[wilton2015]

please can someone explain why the REF relay on meant to protect a 60MVA 132/33KV transformer will trip whenever a 33kv line feeding from the transformer trips on Earth fault.

 

[stevenal]

CT polarity or ratio problem.

 

[davidbeach]

What stevenal said.

 

[ScottyUK]

Reversed neutral CT.

 

[bacon4life]

Less likely, but it could be due to a blue box if you don't keep up with manufacturer notifications on firmware updates.

 

[wilton2015]

Thank you all i am going back to site to look at the polarity, will update u

 

[slavag]

CT connection/polarity problem
Usually neutral CT, as ScottyUK said.

of course possible setting mistake.