Protective relaying system

摘要

A protective relaying system in which the electric stations at both ends of a district of a power system to be protected optically transmit and receive reciprocally the information of the electric stations. A first protective relay device responds to both the electrical quantities from the opposite side terminal and electrical quantities of its own side terminal, and a second protective relay device responds only to the electrical quantities of its own side terminal. The respective protective relay devices are controlled by virtue of error detection circuits and signal discontinuity detection circuits connected to the optical transmission line to thereby discriminating the mere failure in the optical transmission line from the concurrent failures in both the optical transmission line and the transmission line so as to rapidly eliminate the failures.