Thermal Dynamics Corporation

Victor Equipment Company

Steve Norris

Christopher John Conway

Roger W Hewitt

Ken Isenor

Roger Hewitt

A plasma arc torch includes an electrode, a tip, a third element, and a secondary power circuit. The electrode is disposed within the plasma arc torch and adapted for electrical connection to a cathodic side of a power supply. The tip is positioned distally from the electrode and adapted for electrical connection to an anodic side of the power supply during piloting. A plasma chamber is formed between the electrode and the tip. The third element is disposed near a proximal end of the plasma chamber. The secondary power circuit is disposed proximate the plasma arc torch and in electrical communication with the third element. The secondary power circuit is configured to generate a high voltage pulse on the third element using input to secondary power circuit to initiate a first arc to start the plasma arc torch.

Plasma arc torch with secondary starting circuit and electrode

A contact plasma-arc torch having a parts-in-place safety reset circuit and method. The torch includes an electrode and a tip. A safety reset circuit monitors parameters associated with the electrical relationship between the electrode and the tip to determine whether the tip and/or electrode are properly installed. The circuit also monitors an electrical relationship associated with the workpiece to detect when current is flowing in the workpiece when such current is not expected. The torch power supply and associated circuitry includes a soft start capability whereby the full power output of the power supply is supplied to the electrode over time due to the soft start characteristic of a soft start circuit. If the safety reset circuit detects that the tip and/or electrode arc not properly installed, or that current is flowing in the workpiece when such current is not expected, the safety reset circuit resets the soft start circuit. When the soft start circuit is reset, the power applied to the electrode is returned to its initial starting value at or near zero volts. Thus, full power output is not applied to the electrode when the tip and/or electrode are not properly installed.

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New London, NH, United States of America

Steve Norris