JPS648821A - Differential relay - Google Patents

Abstract

PURPOSE:To enable sampling synchronization to be established between two points separated from each other, by regulating a sampling time at one end at least according to a phase difference between a confronted terminal and a self end. CONSTITUTION:By the oscillator 30 of a terminal SS2, a parallel/serial converter circuit 13 is controlled, and synchronized with a sampling timing, the current data of the terminal SS2 is transmitted to a terminal SS1. Signal transmitted from the terminal SS2 is demodulated by a serial/parallel converter circuit 4, and the input as the current data to a phase difference detecting element 5 is provided. By the phase difference detecting element 5, arithmetic is performed on a phase difference between self end current converted by an AD converter 2, and a received remote terminal data, and the output is directed to a delay time controlling element 7. By the delay time controlling element 7, the current values of the self end and the remote end are checked, and it is discriminated whether the power flow of a scale for performing arithmetic on the phase difference between both the ends at high precision is flowing, or not, and when there is sufficient power flow, then the delay time setting value of a variable delay element 8 is changed, and the sampling timing is controlled.