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. 08, 2012
Filed:
May. 08, 2009
John Foster Farrow, Plymouth, MI (US);
John Foster Farrow, Plymouth, MI (US);
Welding Technology Corporation, Farmington Hills, MI (US);
Abstract
The invention comprises a set of methods to detect the resistance of a connection to safety ground and to detect the presence of voltage hazardous to people in systems where an unknown amount of current intermittently flows in the safety ground circuit. Samples of voltage between two points in the safety ground circuit are taken repeatedly. When the voltage caused by the unknown currents in the safety ground circuit is below a preset threshold, a known current is applied and another voltage sample is taken to detect the electrical resistance of the safety ground circuit. If an excessive resistance or voltage is detected, one or more outputs are activated or deactivated to indicate the problem and remove power from the system. The invention requires no current sensor for its operation.