Abstract: Protective relay apparatus which performs a segregated phase current comparison of a three-phase protected line section, with a single relay at each end thereof for making the phase current comparison. The single relay includes a rectifier arrangement which provides a signal responsive to the largest phase current of a predetermined polarity, at any instant. In response to a fault detection, it successively phase compares the signals from its rectifier with the signals of the corresponding phases from the rectifier in the relay at the other line end.