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:
Mar. 14, 1989
Filed:
Aug. 13, 1987
Akio Ito, Hitachi, JP;
Hidenori Sawa, Hitachi, JP;
Hiroshi Sugisaka, Takahagi, JP;
Shigeaki Hayashi, Suita, JP;
Hiroto Nakagawa, Osaka, JP;
Yasuteru Oono, Kobe, JP;
Eiji Haraguchi, Ibaraki, JP;
Hitachi Ltd., Tokyo, JP;
The Kansai Electric, Tokyo, JP;
Abstract
There is disclosed a protecting apparatus for a secondary excitation type variable speed AC generator/motor having a primary winding connected to an electric power system and a secondary winding each phase of which is AC excited by an independent power converter unit. The protecting apparatus is arranged to detect an electrical event which includes at least one of an overvoltage and overcurrent appearing at each phase of the secondary winding of the AC generator/motor, to decide whether the detected electrical event meets a predetermined condition and to close, when the electrical event detected in respect to any of phases of the secondary winding is decided as meeting the predetermined condition, a switch circuit connected in the corresponding phase of the secondary winding.