| 摘要 |
A protective circuit for a plurality of series connected thyristors where each thyristor has in parallel with it a resistance, capacitance type snubber circuit and a metal oxide varistor. The arrangement of the series connected thyristors, snubber circuits and their metal oxide varistors has in parallel with it a main metal oxide varistor. The main varistor is responsive to external transient surges so as to conduct large currents. The outer varistors are selected to have values so as to conduct a much smaller or minimal current relative to the current conducted by the main varistor. In a preferred arrangement, a tuning inductor is in series with the thyristors, snubber circuits and parallel arranged varistors. Also, the main varistor is arranged in parallel with the series connection of thyristor, snubber, varistor combination and inductor, and in series with a bank of capacitors.
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