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. 26, 1996
Filed:
Jun. 07, 1995
Osamu Koyanagi, Hitachi, JP;
Kunio Hirasawa, Hitachi, JP;
Masanori Tsukushi, Hitachi, JP;
Yukio Kurosawa, Hitachi, JP;
Tadashi Sato, Mito, JP;
Youichi Ohshita, Katsuta, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A switching mechanism for use e.g. in a circuit breaker of an underground electric substation has a movable rod which causes opening and closing of an electrical contact and a hydraulic operating system. The hydraulic operating system uses a hydraulic fluid which has a high flammability temperature or is incombustible. Thus, even if such fluid leaks from the hydraulic operating system, the risk of fire or explosion is minimized. The hydraulic operating system may have a sealed tank for the fluid, preferably with a variable volume expansion chamber. In a further development, the hydraulic operating system and possibly parts of the movable rod, is enclosed in a casing which is sealed and is filled with a gas which does not support combustion therein. Thus, the risk of fire or explosion is further reduced. The casing may have a variable volume expansion chamber.