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:
May. 31, 1988
Filed:
Jan. 22, 1987
Yasuo Nagai, Maebashi, JP;
Kazuhiko Kawai, Takasaki, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A detecting circuit for detecting electric abnormality of a pair of feeders is provided with resistors R.sub.A and R.sub.B converting the abnormality of the feeders into a change in voltage, transistors (Q.sub.8, Q.sub.9 and Q.sub.10) supplying or interrupting a current I.sub.B in response to presence or absence of an abnormal state, transistors (Q.sub.5, Q.sub.6 and Q.sub.17) drawing in or blocking a current I.sub.A in response to the abnormal state, a current subtraction element (I) conducting a subtraction of the currents I.sub.B and I.sub.A on an absolute value basis, a current addition element (II) conducting an addition of the currents I.sub.A and I.sub.B, a current addition element (III) adding the output currents of the current subtraction element (I) and current addition element (II), and a voltage comparator (6) subjecting the output current of the current addition element (III) to current-voltage conversion and comparing a voltage thus obtained with a reference voltage so as to obtain an abnormality detection signal, which is used to interrupt the feeding of electricity to the paired feeders when an abnormality is detected.