DIGITAL TRANSMISSION LINE PROTECTION RELAY

摘要

PROBLEM TO BE SOLVED: To self-generate an accurate sampling signal using a deviation result that is obtained by a reference synchronizing signal and an internal clock signal in advance even if the reference synchronizing signal is interrupted. SOLUTION: A digital transmission line protection relay is provided with a deviation calculation means 55 for measuring the deviation between a reference synchronizing signal and an internal clock signal, a reference synchronizing signal monitoring means 57 for monitoring the presence or absence of the reference synchronizing signal, and a sampling signal generation means 54 with a function for generating a sampling signal according to the result of the deviation calculation means 55 and switching to an internal clock signal according to the result of the reference synchronizing signal monitoring result 57. The relay samples the amount of electricity of the transmission line of a power system by a sampling signal being outputted from the sampling signal generation means 54 for judging the presence or absence of the fault of a transmission line. The relay is provided with a deviation storage means 59 for storing a previous calculation value according to the deviation calculation means 55, and a deviation judgment means 58 for giving a deviation measurement result to the sampling signal generation means 54, when the reference synchronizing signal monitoring means 57 detects the interruption of the reference synchronizing signal.