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:
Jan. 24, 1989
Filed:
Dec. 18, 1986
Gunnar Nimmersjo, Vaster.ang.s, SE;
ASEA Aktiebolag, Vaster.ang.s, SE;
Abstract
High resistance ground faults on a transmission line of an electrical power transmission network are detected with the aid of a device comprising a travelling wave model of the line located in measuring stations (P, Q) at either end of the line, which permits the voltage distribution along the line, seen both from P and from Q, to be obtained. A voltage .DELTA.U.sub.Qp is formed as the difference between a votlage in station P, calculated in the travelling wave model in Q, and the corresponding voltage one period earlier. A voltage .DELTA.U.sub.Pp is formed as the difference between a voltage calculated in the travelling wave model at P and the corresponding voltage one period earlier. The corresponding voltage differences .DELTA.U.sub.Pq and .DELTA.U.sub.Qq are calculated for station Q. The voltage difference .DELTA.P is then formed as the difference between .DELTA.U.sub.Qp and .DELTA.U.sub.Pp, and the corresponding .DELTA.Q is formed as the difference between .DELTA.U.sub.Pq and .DELTA.U.sub.Qq. Fault detection is obtained when .DELTA.P>.epsilon..sub.p or when .DELTA.Q>.epsilon..sub.q, where .crclbar..sub.p is the accepted voltage difference at P and .epsilon..sub.q is the corresponding value at Q.