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:
Apr. 11, 1978
Filed:
Dec. 02, 1976
Karl-Friedrich Leowald, Weiher near Erlangen, DT;
Jakob Schenk, Erlangen, DT;
Siemens Aktiengesellschaft, Munich, DT;
Abstract
A protection circuit for protecting the thyristors of a series circuit of several thyristors, each of which has a corresponding firing circuit to which its anode-cathode voltage is applied. The protection circuit comprises: a plurality of first monitoring means, each of which first monitoring means is associated with and at the potential of a different one of said thyristors, and each of which monitoring means generates a first switching signal when either the current carried by its associated thyristor becomes zero or the voltage across its respective thyristor falls below a predetermined negative value; a plurality of first potential-separating transmission means, each of which first transmission means transmits a different one of said first switching signals; an evaluating means; a plurality of second, potential separating transmission means; a plurality of second monitoring means, each of which second monitoring means is associated with and at the potential of a different one of said thyristors, and each of which second monitoring means generates a second switching signal when the voltage across its associated thyristor exceeds a predetermined positive value; and a plurality of logic circuit means each of which is adapted to feed a signal to the firing circuit associated with a different one of said thyristors when the second switching signal generated by the second monitoring means associated with that one thyristor appears during the timing signal transmitted by the second transmission means associated with that one thyristor.