settings distance protection and OC protection

[buskos]

We have two realay protection in HV lines Distance protection and overcurrent protection. The time settings of backup overcurrent protection for earth fualt is 1 sec. During single phase short circuit the trip issue by main distance protection and ARC start in progres. The dead time ARC is 1sec. Some time because one phase is triped during dead time is appear high level values of IE>. This value pickup overcurrent protection and issue the trip also for 1 sec. How we can solve the problem to change the time of OC protection or to increase settings IE>. Please I want your comment and experience.

 

[davidbeach]

If you are single pole tripping you have to disable all ground/earth protection that might be affected by the pole open condition during the time that you have an open pole. 1 sec backup protection time sounds rather long; with two sets of distance relays why are you doing overcurrent backup any way?

 

[slavag]

Yep. David is right.
In case of single phase AR you must block directional E/F protection or chanage time to longer.
David, in our systems, directional ground fault relay with time 1-1.2sec too, but we don't use simple overcurrent relay for back up distance.
Best Regards.
Slava