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:
Mar. 04, 1997
Filed:
Nov. 18, 1994
John D Sanderson, Portland, OR (US);
Radar Engineers, Portland, OR (US);
Abstract
When a fault in an energized power distribution cable flashes over, the surge draws charge from both sides of the line. The fault thus produces a pair of current surges that propagate from the fault in opposite directions along the line. These oppositely-directed current surges create pulsed electromagnetic fields of different directions which, in turn, induce voltages of different polarities in a receiving antenna positioned along the line. The polarity of the first such voltage pulse induced in the antenna indicates the direction from the antenna to the fault. In one embodiment, the line is repeatedly 'thumped,' causing flashovers to recur at the fault. By moving the antenna along the line until the polarity of the initial received pulse inverts, the precise location of the fault can be determined. In another embodiment, direction-indicating fault current indicators according to the present invention are permanently placed at numerous locations in an operating AC power distribution system, in anticipation of a fault. When a fault occurs, the polarity of the first received electromagnetic fault pulse at each device indicates the respective direction from the device to the fault.