| 摘要 |
A thyristor arrangement is created having thyristor branches (10) forming a three-phase bridge. Each of the thyristor branches (10) has a series circuit of thyristors (11) to each of which a gate signal is applied which is generated by a circuit (25) which produces a signal that switches the gate into the operating position, a circuit (17) which produces the gate light signal, and a circuit (19) which produces an electrical gate signal. A branch overvoltage suppressor (12) is connected in parallel with each of the thyristor branches (10) so that the branch overvoltage suppressor (12) is discharged by a voltage surge which is supplied to the thyristor branch (10). The discharge is detected by a voltage dividing resistor (16) and a discharge detection light signal generating circuit (20), and a discharge detection light signal (S4) is supplied to a discharge detection light signal receiver circuit (22). The discharge detection light signal receiver circuit (22) responds to the discharge detection light signal (S4) and causes an invertor (23) and an AND gate (24) to block the gate signal described above. Accordingly, in such a situation, the thyristors (11) are not switched into the operating position, and an excessive switching loss is thus prevented. <IMAGE>
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