Turn-off arrangement for a direct current switching device which is rendered non-conducting by the application of a reverse voltage

Claim 1

A TURN-OFF ARRANGEMENT FOR A DIRECT CURRENT SWITCHING DEVICE WHICH IS INCORPORATED IN A SUPPLY PATH FROM A SUPPLY SOURCE TO A LOAD TERMINAL, THE SWITCHING DEVICE BEING OF A KIND WHICH IS RENDERED CONDUCTING ON APPLICATION OF A SWITCHING SIGNAL TO SAID DEVICE, AND IS RENDERED NON-CONDUCTING BY THE APPLICATION OF A REVERSE VOLTAGE, SAID ARRANGEMENT COMPRISING A UNILATERALLY CONDUCTIVE CURRENT PATH, A STORAGE CAPACITOR IN SAID PATH FOR STORING SAID REVERSE VOLTAGE, A SECOND SWITCHING DEVICE FOR APPLYING SAID STORED REVERSE VOLTAGE TO SAID SWITCHING DEVICE IN SAID SUPPLY PATH, AN INDUCTANCE IN ANOTHER SUPPLY PATH FROM SAID SUPPLY SOURCE TO SAID LOAD TERMINAL AND IN PARALLEL WITH SAID UNILATERALLY CONDUCTIVE CURRENT PATH, AND A THIRD SWITCHING DEVICE FOR CONNECTING SAID INDUCTANCE IN A PATH ACROSS AND SUPPLY SOURCE, SUCH THAT SAID STORAGE CAPACITOR IS CHARGEABLE BY CURRENT FROM SAID INDUCTANCE WHICH CONTINUES TO FLOW IN SAID INDUCTANCE ON SWITCHING OFF OF SAID THRID SWITCHING DEVICE.