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AssigneeHypertherm, Inc.
InventorsJeffrey L. Peterson, William V. Bailey
Estimating the term…
A high frequency, high voltage starting circuit for a plasma arc cutting torch is operated in pulses to restart the torch if an initial arc extinguishes before the arc transfers to the workpiece. The starting circuit includes a D.C. power supply with its negative output connected to an electrode of the torch. A positive output is connected to a nozzle, and at a higher positive voltage, to a workpiece. A surge injector circuit of a resistor and surge capacitor is connected in parallel with the power supply to supply current to the arc as soon as breakdown occurs. The duration of the interval between restart pulses is sufficient to allow the surge injector circuit to recharge to a value that will reliably restart the arc as the power supply ramps up to a steady state pilot arc current.
A method of reliably starting and maintaining an arc in a plasma arc torch where a high frequency, high-voltage (HFHV) signal initiates a breakdown in a plasma gas flowing between the electrode and the nozzle, and where a surge injection circuit includes a surge capacitor initially charged to a predetermined value and a DC power supply connected across the surge injection circuit, said surge injection circuit supplying current to maintain the arc as a pilot arc and then a transferred arc, comprising
Dependencies are inferred from the claim text.