JPS54150649A - Checking signal transmission line of carrier protective relay - Google Patents

Abstract

PURPOSE: To enable the checking of a signal transmission line withut wrong breaking when a meter transformer at a variable power supply end is defective.

CONSTITUTION: The checking is started by a checking signal control circuit 401 at the variable power supply end B to make a trip lock signal S1 into "1" to clock a circuit breaker 407 at the end B. After the time T1 of confirmation of the trip lock at the end B, a signal F1 (trip lock side's signal) is transmitted from the end B to a fixed power supply end A through the signal transmission line 402 for a time T2. A signal F2 (trip permission side's signal) is then transmitted from the end B to the other A through the transmission line for a time T3. The signal F1 is thereafter continuously transmitted from the end B to the other A through the transmission line. At the end A, checking signal reception control circuits 403, 404 are regulated on condition that the signals F1, F2 are received for prescribed times. The signal F2, the signal F1 and the signal F2 are then sequentially transmitted from the end A to the other B through the signal transmission line 402. If these signals F1, F2 are received at the end B for prescribed times, the signal transmission line is rgarded as normal.

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