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. 26, 2015
Filed:
Dec. 31, 2009
Bin Su, Beijing, CN;
Youyi LI, Beijing, CN;
Torbjorn Einarsson, Vastmanland, SE;
ABB Technology Ltd., Zurich, CH;
Abstract
The invention provides a method and apparatus for detecting communication channel delay asymmetry between transmission line protection devices. The method comprises: calculating, repeatedly, clock disparity between clocks of the protection devices and communication delays at different paths of the communication channel; comparing the latest calculated clock disparity and communication delays with previously calculated clock disparities and communication delays, respectively; determining a channel switching has happened if a change of the calculated clock disparity exceeds a first threshold, or a change of the calculated communication delays for any path exceeds a second threshold; and determining the channel delays as asymmetrical if a difference between the calculated communication delays of the different paths after the channel switching exceeds a third threshold.