Experience sharing: self powered relays - simulated over current phase & earth fault testing

While self-powered relays technology is known and in use over few decades in secondary distribution network, there is very limited understanding & published literature pertaining to high accuracy production & on-site testing of protection functions offered by these devices. There are often disagreements between utility & OEM when high precision, sensitive over current phase or earth fault scenario needs to be tested under simulated conditions due to misleading extensions of aux. powered relay testing approach. This paper, after detailing non-linear load presented by the self-powered relay, tabulates test results on ABB Self powered relay designs. Later, with supportive data analytics provides understanding of constraints influencing the simulated testing performance of over current phase and earth fault protection of self-powered relays.