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:
Feb. 07, 1984
Filed:
Feb. 24, 1982
Applicant:
Inventors:
Tadao Kawai, Hitachi, JP;
Tomoharu Nakamura, Hitachi, JP;
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H02H / ;
U.S. Cl.
CPC ...
361 42 ; 361 49 ;
Abstract
A ground detecting device for detecting a ground fault in a DC circuit, through which a DC power produced by converting a poly-phase AC power by an AC-DC converter is transmitted and which is connected at an earth point to the earth, is arranged to detect an earth current flowing through the earth point and extract a DC component, if any, from the detected earth current and to judge whether a ground fault has occurred or not by comparing the level of the DC component with a predetermined reference level.