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:
Dec. 06, 1983
Filed:
Jun. 16, 1981
Applicant:
Inventor:
Bernt Bergdahl, Ludvika, SE;
Assignee:
ASEA Aktiebolag, Vater.ang.s, SE;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G08B / ; H03H / ;
U.S. Cl.
CPC ...
340653 ; 333 / ; 361113 ;
Abstract
An electric filter, for example an harmonic filter in an HVDC convertor, has, in addition to the main filter, a low power model filter having the same frequency characteristic as the main filter. The model filter is supplied with a voltage which is a scaled-down version of the voltage appearing across the main filter. The currents in the main and model filters are sensed at corresponding places in the filters and compared. If a deviation occurs between the sensed currents in the main and model filters, an indicating signal is generated which indicates a deterioration in the performance of the main filter.