DEFECT MONITORING SYSTEM FOR OPTICAL INDIRECT FIRING TYPE THYRISTOR VALVE

摘要

PURPOSE:To enable to discriminate the content of a defect in a valve by trans mitting a light signal to a ground potential side controller when a normal or self-firing pulse is supplied to a thyristor, and further providing a difference in the pulse width of both. CONSTITUTION:Light emitting diodes 7 are provided between the coupling point of a self-firing circuit 3 and a normal firing circuit 2 and a gate terminal of a thyristor element 1, and a light signal is generated from the diode 7 when there is any of outputs of the circuits 3, 2. The output pulse width of the circuit 2 is longer than the output pulse width of the circuit 3. The light signal of the diode 7 is transmitted to a ground potential side controller 5 to distinguish the normal firing pulse from the self-firing pulse.