Abstract: A device for monitoring thyristors of a high-voltage valve comprises thyristor voltage detectors coupled via light guides to a buffer storage unit through a selector. Also provided are an OR gate assembly, an adder, a memory unit, and a comparison unit, which are placed in series and coupled to a control unit. The OR gate assembly is connected to the buffer storage unit which is also coupled to the control unit. A second input of the comparison unit is connected to a second output of the adder, while its output is connected to an indicator signalling the quantity of disabled thyristors and to a unit protecting the high-voltage valve against breakdown. The selector is also connected to an indicator signalling the numbers of disabled thyristors.

Abstract: The proposed method consists in that a narrow control pulse is applied to the thyristors of the arrangement at the beginning of the conduction interval of the arrangement. The positive voltage across the monitored thyristors is measured and a monitor signal is formed at the point in time when the voltage reaches a preset level. Using the received monitor signals, one can count the number of the thyristors whose positive voltage exceeds a preset level. At the point in time when the number of the monitor signals reaches a preset value, additional narrow control pulses are applied to the thyristors.The proposed control system comprises devices for measuring the positive voltage across the monitored thyristors and an adder connected to the devices. The adder and a reference signal source are coupled to a comparison circuit which, like a sync pulse source, is connected to an AND gate. The AND gate and the sync pulse source are connected to an OR gate which couples an amplifier-former connected to the arrangement.