Thermal Dynamics Corporation

David M Morris

David A Tatham

James M Gregorich

A pilot arc circuit for a plasma torch establishes a pilot arc current in the channel between the torch electrode and torch tip at a first target level which is greater than a predetermined minimum current sufficient to maintain a stable pilot arc. After a period of time following pilot arc initiation, the pilot arc current is reduced to a second target level which is greater than or equal to the predetermined minimum current so that damage to the torch is reduced by minimizing wear on the parts. The pilot arc current is established and maintained as a function of a pilot arc reference signal. Pulsing the pilot arc current assists in main arc transfer and enhances pilot arc stability.

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Claremont, NH, United States of America

David M Morris