| 摘要 |
PROBLEM TO BE SOLVED: To provide a failure detecting circuit which is capable of ensuring normal operation of a breaker even if a semiconductor switching element for operating a high-speed mechanism is failed as well as surely detecting a malfunction of a semiconductor switching element or breaking of a trip coil or the like. SOLUTION: This failure detecting circuit is assembled and operated as follows: two thyristors 41, 42 are inserted in series between a magnetic repulsion coil 18 which drives a movable contact point 12 of a vacuum breaker 10 by electromagnetic force and an electric source; thyristors 20 are also inserted in series between a high speed trip coil 16 and its electric source; and then those thyristors are operated at the same time by an output signal of a thyristor driving circuit 27. Wherein, a thyristor failure detecting circuit for detecting failures of the thyristors is connected to the respective thyristors in parallel, and a coil breaking detecting circuit 47 for detecting disconnections of the coils is connected to the respective coils in parallel. The each failure detecting circuit has a photocoupler as a main component. COPYRIGHT: (C)2004,JPO
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