Effect of fault resistance on the performance of mho relays

Abstract EN

For distance protection to perform its function perfectly without errors, it should be characterized with ideal characteristics that is to operate within forward faults those are included by protection zone, and to exclude the outer faults.

In order to get an ideal tripping area for distance relays, all the factors and limitations imposed by power system on the measuring accuracy of distance relays must be identified.

This paper includes a study of the fault resistance effect on the performance of distance protection when using mho relays.

This study is done by steady state analysis of fault circuit to find the current & voltage at the relay location for different value of fault resistance for Line to ground faults and double line to ground faults.