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:
Nov. 28, 1989
Filed:
May. 26, 1987
Michael Hausler, Weilheim, DE;
Asea Brown Boveri AG, Baden, CH;
Abstract
With electric valves (7) having several series-connected thyristore (T1 . . . Tn; T1' . . . Tn'), individual thyristors may become defective, so that they do not withstand the blocking voltage applied to them. For the simplified checking of such defects, a process is specified which does not require any individual monitoring on the spot, i.e. for high potential. For this purpose, in the blocked state of the valve (7), all thyristors of one current direction, apart from at least one thyristor being tested, are triggered within a predeterminable triggering interval. If a valve current (i.sub.R) then flows, an indicating and registering device (A1 . . . An) indicates in which thyristor stage the defect has occurred. This status check is preceded by a preliminary test in which it is checked whether all thyristor triggering channels are in order. All thyristors are triggered in this test. If no valve current (i.sub.R) occurs, a triggering channel fault signal (S.sub.U0) is generated.