The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 21, 1987
Filed:
Sep. 12, 1985
Siemens Aktiengesellschaft, Berlin and Munich, DE;
Abstract
This invention concerns a procedure to operate a turn-off thyristor which can be set to a current-conducting state or a current-blocking state as a function of a switch-on command or a switch-off command. To permit particularly reliable and optimal operation of the turn-off thyristor, the voltage between its gate terminal, G, and its cathode terminal, K, is detected and when it drops below a negative threshold current value U.sub.GKS, a status signal, Z, is generated which indicates the current-blocking state of the turn-off thyristor. A further embodiment detects the gate current of the turn-off thyristor and after the appearance of the switch-off command, the status signal is generated as the polarity changes in accordance with the time derivative of the gate current. An overload of the turn-off thyristor is best recognized by having simultaneous to the appearance of the switch-off command, a time function with a preset expiration time initiated, and having a malfunction notification signal, F, generated for protective ignition of the turn-off thyristor if the time function expires prior to the appearance of the status signal.