摘要 |
<p>The protection circuit has a transformer (10) with two separate identical primary windings (W1,W2) each in series with one of two thyristors (21,22) and an oppositely-poled diode (11,12) in a return supply path (Z1,Z2). The secondary winding (W3) of the transformer is connected to a full wave bridge rectifier (13). The dc output of the bridge is connected to the ends of the primary windings. The turns ratio of the windings (W1,W2,W3) is 1:1:2. The windings are tightly coupled. The advantage lies in not having to choose the turn-off voltages of the thyristors and diodes specially -- i.e. sufficient protection is provided without taking this measure.</p> |