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:
Jul. 04, 2000
Filed:
Oct. 08, 1998
Jeffrey B Roberts, Pullman, WA (US);
Tony J Lee, Pullman, WA (US);
David E Whitehead, Pullman, WA (US);
Schweitzer Engineering Laboratories, Inc., Pullman, WA (US);
Abstract
A DC monitoring system is provided in each protective relay in an electric power substation to detect DC grounds on the DC supply system. The DC monitoring system includes a first portion which indicates the presence of a DC ground. In a second portion of the system, the voltages at the contact inputs of the relay are recognized and compared against a standard voltage value range. An indication is provided when the recognized voltage is within said range. The combination of the indications from the first and second portions is useful in determining the location of DC grounds in the substation DC supply system.