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:
Oct. 05, 1999
Filed:
Jun. 16, 1998
Armando Guzman-Casillas, Pullman, WA (US);
Luther S Anderson, Pullman, WA (US);
Schweitzer Engineering Laboratories, Inc., Pullman, WA (US);
Abstract
The residual phase currents for each selected winding of a transformer are first determined and then summed to provide a value designated I.sub.X. The neutral current for the transformer is also determined, with the neutral current being designated I.sub.Y. A directional element calculates a torque value T according to the following formula: T=R.sub.e (I.sub.X .multidot.I.sub.Y *). This torque value will be negative for an external (reverse) fault, and positive for an internal (forward) fault. The quantity of the torque is compared against threshold values before a forward or reverse fault for the transformer is declared.