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:
May. 01, 1990
Filed:
Nov. 23, 1988
Allan T Johns, Swindon, GB;
National Research Development Corporation, London, GB;
Abstract
Discriminating circuits are coupled to receive signals from a protected transmission circuit. Each discriminating circuit also receives from a direction detector signals indicating whether any fault which occurs is forward of, or reverse of, a predetermined point. The discriminating circuit is arranged to produce an output signal to trip a circuit breaker of the protected circuit only if a fault occurs within the protected circuit. In this respect, the discriminating circuit only outputs a trip signal if it receives within the same time period both a signal from the direction detector indicating that the fault is appropriately located, and high frequency signals from the protected circuit. The system thus utilizes the high frequency noise invariably generated when faults arise in transmission circuits. The system for protecting transmission circuits has the advantage that it provides good discrimination of faults without requiring communication links between discriminating circuits at each end of a protected circuit, as has previously been necessary.