OVERCURRENT RELAY HAVING DIRECTIONAL CHARACTERISTIC

摘要

PROBLEM TO BE SOLVED: To provide an overcurrent relay having directional characteristics for removing a transmission-line accident and an in-plant accident at a high speed even in usage at a receiving point for a power plant.;SOLUTION: The overcurrent relay 10 having directional characteristics for a short-circuit accident includes an accident-direction decision part 20 obtaining phases to the line voltages V_rs, V_st and V_tr of phase currents I_r, I_s and I_t in an R phase, an S phase and a T phase for a transmission line and line currents I_rs, I_st and I_tr respectively and deciding the direction of the short-circuit accident on the basis of the obtained phases. The overcurrent relay having directional characteristics for the short-circuit further includes a relay arithmetic processor 14 generating a trip signal S_T when any of the line currents I_rs, I_st and I_tr or all current values of the phase currents I_r, I_s and I_t are not less than a power transmission direction or power reception direction current setting valve or more when the direction of the short-circuit accident is decided by the accident-direction decision part 20.;COPYRIGHT: (C)2010,JPO&INPIT