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. 12, 2002
Filed:
Jan. 21, 2000
Mark A. Ulrich, New London, WI (US);
Jeffery J. Gadamus, Hortonville, WI (US);
Illinois Tool Works Inc., Glenview, IL (US);
Abstract
A method and apparatus for supply welding, plasma cutting, and/or induction heating power having a ground fault interrupt (GFI) protection circuit is disclosed. The primary winding of a monitoring transformer in the GFI protection circuit is connected between the high frequency floating output of the power supply and ground. One end of the secondary of the monitoring transformer is connected to a voltage source. The other end of the secondary is connected to an impedance. The other end of the impedance is connected back to the voltage source to form a voltage divider across the voltage source. Changes in the impedance between the floating output of the power supply and ground are sensed by the GFI protection circuit and converted into a voltage. This voltage is filtered, rectified, and calibrated into a dc sense signal. The sense signal is compared to a threshold signal. In the event the sense signal exceeds the threshold signal, an interrupt signal is sent to the power supply and the power supply shuts down.