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. 17, 1988
Filed:
Sep. 17, 1987
Applicant:
Inventor:
John T Hampson, Chester, GB;
Assignee:
The Electricity Council, London, GB;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H02H / ;
U.S. Cl.
CPC ...
361 36 ; 361 65 ; 361 76 ; 361 80 ; 361 83 ; 361 85 ; 364483 ;
Abstract
It is desirable to provide remote digital protection of distribution transformers. This specification discloses a protection system able to measure and compare increases in both negative and positive phase reference currents on a distribution cable feeding a transformer and to trigger a circuit breaker to isolate the cable only if the negative sequence current increase exceeds a predetermined proportion of any simultaneous positive sequence current increase. Consequently, engergizing with a 12.5% unbalance current has been found possible without false tripping.