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. 14, 1980
Filed:
Aug. 28, 1978
John R Sherwood, Arlington, VA (US);
AMF Incorporated, White Plains, NY (US);
Abstract
A ground monitoring circuit for detecting the existence and proper connection of the ground wires in an electrical power cable of a type commonly used at a surface mining site. A complete conductive loop is established between the ground conductor, or conductors, and the ground check, or pilot, wire of the cable. A sensing signal at a frequency higher than the power frequency is coupled onto the ground monitoring loop. The voltage and current in the loop are separately sampled. Various comparisons of the voltage and current samples are made to detect any deviation in the resistance and/or reactance characteristics of the loop. Any deviation from desired conditions in the loop produce one or more output signals that change the condition of a trip relay. The trip relay initiates action that ultimately opens circuit breakers to remove power from the cable.