Calculation for Earth fault relay

[Jason_tcs]

Dear friends,May I know how to calculate the Earth fault relay/ Earth leakage relay? When we going to use them? Thank you.Regards,
Jason

 

[anorlunda]

Welcome to PF.

I suggest the textbook "The art and science of protective relaying ". You can read it online free at

http://www.gegridsolutions.com/multilin/notes/artsci/

 

[berkeman]

Dear friends,May I know how to calculate the Earth fault relay/ Earth leakage relay? When we going to use them? Thank you.Regards,
Jason

Welcome to the PF.

In addition to anorlunda's reference, you can read through the Wikipedia page about smaller-scale Earth Fault protection devices:

https://en.wikipedia.org/wiki/Residual-current_device