Abstract: Disclosed is a system that provides protection for a high voltage transmission line. The system employs improved polarizing and operating signals for both a phase selector relay and a distance measuring relay. The improved polarizing and operating signals provide an accurate out-of-phase relationship during the presence of normal conditions existing on a high voltage transmission line and an in-phase relationship during the presence of fault or abnormal conditions existing on the high voltage transmission line. The accurate phase relationships are utilized by phase comparator circuits of each of the phase selector and distance measuring relays to obtain desired operating characteristics for each relay. In another embodiment, the desired operating characteristics of the phase selector and distance measuring relays are obtained by an amplitude comparator circuit.