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:
Dec. 24, 1985
Filed:
Oct. 31, 1984
Isabelle Heller, Sevres, FR;
Paul Loewenstein, Mountain View, CA (US);
Enertec, Montrouge, FR;
Abstract
A directional relay for providing indication of the direction of a fault on an electric power transfer network has an adder (9), a subtractor (10) and filters (11) which receive signals from voltage and current transformers (6,7) and derive signals related to fault-induced forward and backward transient waves on the network. To ensure reliable operation even when the relay is close to a low impedance element such as a generator (2), the forward wave related signal is delayed in a delay unit (12) by an amount equal to the propagation time of the wave along the section protected by the relay, before the difference between its square and that of the backward wave related signal are integrated (16) to derive the fault direction signal. If the protected section has a low distributed capacitance, the voltage and current signals can instead be combined by a differentiator (22) and adder (23) and filtered (11B) to produce a signal related to the forward transient wave appearing at a point X along the protected section. The integrator (16) receives the product of this signal and the filtered current signal.