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:
Oct. 05, 1976
Filed:
Dec. 06, 1974
Masami Okamura, Musashino, JA;
Yoshihumi Oura, Yokohama, JA;
Yoshihiro Sano, Katsuta, JA;
Junichi Makino, Hitachi, JA;
Yoshiteru Miki, Hitachi, JA;
Hitachi, Ltd., BOTH OF, JA;
The Tokyo Electric Power Co., Inc., BOTH OF, JA;
Abstract
Protection of an electric power system is attained under control of a digital computer. Voltage and current of the electric power system to be protected are subjected to sampling at a predetermined sampling frequency and are applied to the computer after being converted into digital signals. The computer computes the product of these two digital signal inputs. The signal thus obtained is added to a preceding signal representing the product of voltage and current taken at time before a predetermined period of time so that unnecessary frequency components included in these signals can be removed. Then, the level of the resultant signal (which is free from the unnecessary frequency components) is compared with the level of a reference signal. When the former is greater than the latter, there is a fault in the electric power system, and necessary protective measures are taken to protect the electric power system.