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. 10, 1982
Filed:
Mar. 26, 1980
Yasuhiro Kurosawa, Hino, JP;
Tetsuo Matsushima, Fuchu, JP;
Tokyo Shibaura Denki Kabushiki Kaisha, Kawasaki, JP;
Abstract
A digital type distance relay system comprises a sampling and hold circuit for sampling and holding the current in and voltage on a power transmission system, an A/D converter for receiving the outputs of the sampling and hold circuit through a multiplexer and converting the received analog quantities into corresponding digital quantities I and V, and a digital computer. The digital computer includes a data memory for memorizing the current I and voltage V and also a digital voltage V.sub.p having a predetermined relation to the voltage V, a setting memory for memorizing a setting value Z.sub.0 for setting a range of protection of the power transmission system, a ROM for memorizing a program for executing an arithmetic operation according to the formula .vertline.I.multidot.Z.sub.0 +K.sub.1 V.sub.p .vertline.-.vertline.I.multidot.Z.sub.0 -V-K.sub.2 V.sub.p .vertline..gtoreq.K.sub.0 as well as the constants K.sub.1 and K.sub.2 and minimum sensitivity value K.sub.0, and a CPU. The CPU executes the program dealing with the afore-mentioned arithmetic operation formula and produces a command signal for taking an action of protecting the power transmission system if the arithmetic operation formula is satisfied while producing a command signal for taking no protective action if the formula is not satisfied. The protective action can be provided even in case when the voltage V in the arithmetic operation formula is zero in level.