SU995225A1 - Device for testing conducting state of thyristors - Google Patents

Description

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The invention relates to converter technology and can be used in protection and signaling devices of valve converters.

Devices for protecting a thyristor converter are known, which contain current sensors, positive and negative polarity threshold elements, a one-shot and element 1.

The disadvantage of these devices is their low reliability.

Closest to the present invention is a device for protection of a three-phase bridge converter against the passage of control pulses, which in each control channel contains a current transformer, the output of which is connected to the inputs of two indicators of positive and negative polarity, two one-vibrator and two And elements, whose outputs are connected to output terminals 2.

The disadvantages of the known device are low reliability and accuracy.

The purpose of the invention is to improve the accuracy and reliability of the device for monitoring the conductive state of the valves.

The goal is achieved by the fact that in the device in each control channel, the outputs of the indicators of positive and negative polarity are connected respectively to the first inputs of the first and second 5 elements AND, the second input of the first element AND connected through the first one-vibrator to the output of the second element AND, and the second input the second element And is connected through the second one-shot to the output of the first element I.

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FIG. 1 shows a functional diagram of the proposed device; in fig. 2 diagrams of stresses, which show his work.

The device for monitoring the conductive state of the valves 1-6 (Fig. 1) contains 15 in each control channel a current transformer 7 with a load resistor 8, indicators of positive 9 and negative 10 polarities of signals, one-shot 11 and 12, elements And 13 and 14 and output terminals.

The device works as follows 20

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When there is a positive voltage at the output winding of the current transformer 7, the signal "1," appears at the output of the indicator 9, and at a negative voltage, the signal "1 appears at the output of the current transformer 7" 1 appears at the indicator output 10. Indicators 9 and 10, in addition to the useful signals, reverse current transformer spikes occurring in the frequency of falling to zero phase currents are also recorded. At the moment of the end of the negative phase current, the one-shot 11 is triggered by the back edge of the pulse from the output of the element And 14. The channels of the device for monitoring the conductive state of other thyristors work similarly.

The use of the invention provides, without deepening the sensitivity of the indicators, reducing false alarms and increasing the accuracy of the device for monitoring the thyristor conducting state, since the delay of the device by the time of a single vibrator can occur only in the rare case of an instantaneous polarity change of the phase current of the converter, i.e. turning on the thyristor 4 at the time of closing the thyristor 1.

Claims (2)

1. USSR author's certificate number 323928, cl. H 02 M 1/08, 1970. 2. USSR author's certificate number 687523, cl. H 02 M 1/18, 1977.  f  four fu