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:
Feb. 05, 1991
Filed:
Sep. 12, 1986
Applicant:
Inventor:
Francis Y Hung, Kanata, CA;
Assignee:
Northern Telecom Limited, Montreal, CA;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H02H / ;
U.S. Cl.
CPC ...
361 57 ; 361111 ; 361119 ; 379399 ; 379412 ;
Abstract
A protection arrangement for a two-wire line, such as a telephone subscriber line, includes a transformer having two primary windings and a secondary winding. The primary windings are connected in series with the wires of the line with phases such that common mode (longitudinal) currents on the line induce a current in the secondary winding, whereas loop currents do not. The induced current in the secondary winding is amplified and used to trigger a protection device, such as a triac or SCR and diode bridge arrangement, to short circuit the line for the duration of any excessive current thereon.