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:
Aug. 28, 1984
Filed:
Apr. 30, 1981
Applicant:
Inventor:
Noriyoshi Suga, Fuchu, JP;
Assignee:
Tokyo Shibaura Denki Kabushiki Kaisha, Kawasaki, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G01R / ;
U.S. Cl.
CPC ...
377 28 ; 377 39 ; 377 43 ; 324 / ; 324 / ;
Abstract
A digital frequency relay for use in protecting an electrical power transmission line in the event of frequency deviations indicative of a fault condition, including an input device for receiving AC electric signals, and an oscillator for generating a reference frequency, which are connected to respective first and second counters which respectively count the number of output pulses from the oscillator during the AC electric signal positive half-cycle, and during the AC electric signal negative half-cycle. The resultant output from the first and second counters is added and compared with a set value to produce a trip signal for the frequency relay.