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. 30, 1997
Filed:
Oct. 20, 1995
Applicant:
Inventors:
Jeffrey B Roberts, Moscow, ID (US);
Daqing Hou, Pullman, WA (US);
Assignee:
Schweitzer Engineering Laboratories, Inc., Pullman, WA (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H02H / ;
U.S. Cl.
CPC ...
361 89 ; 361 80 ;
Abstract
The voltage and current conditions on a power transmission line are monitored to determine the coincidence of a low voltage condition and a lack of a high current condition. The coincidence of those two conditions is indicative of a CCVT transient, and the tripping action from zone 1 distance elements is delayed for a period of 1.375 cycles. The tripping delay is supervised by a fault impedance determination, which, if a threshold is exceeded, the remaining portion of the time delay is eliminated, so that a trip is allowed if the time delay period has not expired.