Importance

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Abstract

An electronic circuit for a plasma arc torch that initiates the transfer of a pilot arc into an operating arc before operating current is sensed in a workpiece. The electronic circuit includes a power circuit output inductor, and a pilot circuit having a disconnect in series with the pilot electrode of the plasma torch. An oscillator is coupled to the disconnect to periodically open-circuit the pilot circuit before current is detected in the workpiece by a current sensor. The periodic cessation of current caused by the disconnect causes the output inductor to create a voltage spike that assists in the transfer by attempting to establish the operating arc between the electrode and the workpiece. Optionally, a pilot inductor in the pilot circuit provides transitory power to sustain the pilot arc during the time the pilot current source is ceased, should arc transfer not occur. If transfer occurs, the pilot circuit is kept open-circuited, else the pilot circuit is closed until current is sensed in the workpiece indicative of arc transfer or the oscillator again open-circuits the pilot regulator disconnect.

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First Claim