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:
Jun. 16, 1987
Filed:
Jun. 11, 1986
Michael Peppel, Uttenreuth, DE;
Theodor Salzmann, Erlangen, DE;
Siemens Aktiengesellschaft, Munich, DE;
Abstract
For recognizing the blocked state of a thyristor which can be switched off (GTO thyristor), especially also if it is alloyed through or the driver addressing the thyristor is defective, a state signal indicating the actual advent of the blocked state is generated after the occurrence of a turn-off signal, if the derivative in time of the gate current has exceeded a positive upper limit, which indicates that the thyristor has been turned off successfully. The maxima of the derivative in time of the gate current are almost independent of the actual anode-cathode current to be extinguished. The derivitive in time of the gate current is advantageously determined via a coupling inductance. Preferably, the method and apparatus are used with a mutual adaptive turn-on interlock of GTO thyristors in converter equipment and can be urged to release protective measures in time if permanent conduction (short circuiting) of a thyristor occurs.