Effect of transmission line loading on the performance characteristics of polyphase distance relay elements

The performance characteristics of a polyphase element for the detection of phase faults is examined. The results show the effect of transmission line loading and reach setting on the detection characteristics of forward faults. The polyphase element exhibits tendencies to under-reach for far-end as well as close-in faults with zero fault resistance, under some conditions. The results are presented in a manner that facilitates ready assessment of the expected performance of a polyphase element in a particular application.<>