The line distance protection relay is dedicated transmission overhead line and cable protection, control and automation IED.
The protection relays provide a variety of versatile protection functions along with the main line distance protection (21) such as teleprotection schemes (POTT, PUTT etc.), current protection (50/51, 50/51N, 67/67N, 46/46BC), voltage protection (27, 59, 47), frequency protection (81U/81O/81R), power protection (32/37), power swing/out of step detection (68/78), switch on to fault protection (SOTF), breaker failure protection (50BF). The scope of functions is supplemented with the automatic reclosing function (79) with synchro-check/synchro-switch feature (25). Voltage transformer supervision and dead line detection function are implemented in the configuration. Because of the implemented control, measuring and monitoring function, the IED can also be used as a bay control unit.