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. 21, 1981
Filed:
Mar. 23, 1978
Masaki Murashita, Hitachi, JP;
Seizo Nakano, Mito, JP;
Hiroshi Itoh, Hitachi, JP;
Shigeo Shiono, Hitachi, JP;
Takeshi Takahashi, Hitachiota, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
In an enclosed-type switching device having at least a pair of electric contacts, a method for checking the contacts without visual inspection wherein with the contacts closed, the resistance value between outer terminals connected to the contacts is measured and compared with a reference resistance value, so that the result of comparison is used to determine the degree of damage of the contacts. Also disclosed is an auxiliary apparatus for use with an enclosed-type switching device to facilitate application of the above-mentioned method, especially when the switching device is equipped with a plurality of parallel-connected sequentially closed or opened contact pairs. The auxiliary apparatus is arranged to interrupt the sequential operation of the contact pairs so that the resistance is measured during the interruption of the operation.