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:
Dec. 01, 1998
Filed:
Jul. 28, 1997
Joseph A Daniel, Mentor, OH (US);
The Lincoln Electric Company, Cleveland, OH (US);
Abstract
An arc retract circuit for use in a plasma arc system with a torch having an electrode and a nozzle, a power supply for providing a D.C. current, a power circuit for connecting the power supply across said electrode and a workpiece to be cut, a power switch for connecting the nozzle to the power supply when in a closed condition defining a pilot arc mode of operation and for disconnecting the nozzle from the workpiece when in an open condition defining a cut mode of operation, an amplifier for regulating said power supply to a first set current when in the pilot arc mode and a second set current when in the cut mode, and an arc retract circuit for shifting the power switch from the open condition to the closed condition, which arc retract circuit includes a current sensing circuit for creating a first signal representing the actual current applied by the power supply to the power circuit, structure for creating a second signal representative of a current level below the second set current, and switch operations structure for closing the power switch when the first signal is substantially equal to the second signal.