JPS5475051A - Phase comparison relay - Google Patents

Abstract

PURPOSE: To make a decision capable as an internal fault when caused a phase above an expected value, by means of transceiving a phase comparison signal so that a phase of current at both ends of the protected section may be in the same phase at the time of current conduction.

CONSTITUTION: At a side of end A and B, a current, flowing in a transmission line 10, is taken out by a current transformer 11A, 11B, being fed to a square wave conversion circuit 12A, 12B having a level settling function. And an output of the above is given to an on-delay timer circuit 12A-a, 12B-a. A signal from the above circuit is transmitted to a remote end receiver 14B, 14A through a transmitter 13A, 13B. And an intra-end square wave signal, outputted from 12A-a, 12B-a, is processed a compensation of transmission delay in a delay compensation circuit 15A, 15B, being transmitted to a NAND circuit 18A, 18B together with the received signal, with an output of the before said compared with a transmission signal of the intra-end in an AND circuit 19A, 19B. The above described AND circuits 20A, 20B will be a different AND circuit, when a difference is produced between the current phase in those above, each of the outputs will be fed to a time setting circuit 22A, 22B through an OR circuit 21A, 21B. For a measured value exceeding the expected value, a decision is made as an internal fault.

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