Illinois Tool Works Inc.

Joe Schneider

Tim A Matus

Rick Hutchison

A plasma arc cutting power supply, and method of providing plasma cutting power, is disclosed. It includes a source of power having, preferably an engine or transformer based power source, that provides a main power output and an auxiliary power output. A two-state configuration circuit is in electrical communication with the auxiliary power output. The auxiliary power output receives voltage of a first magnitude with a non-floating ground when the configuration circuit is in its first state. The auxiliary power output receives voltage of a second magnitude, preferably different than the first magnitude, with a floating ground, when the configuration circuit is in its second state. When a plasma cutting circuit is connected to the auxiliary power output the configuration circuit is set in its second state. The plasma cutting circuit includes at least one chopper. A safety circuit that disables the plasma output includes a GFI or optical isolator.

Plasma cutter for auxiliary power output of a power source

A power supply with an input protection circuit is disclosed. The protection circuit includes a thermistor that heats up if the power supply is mistakenly connected to an excessive input voltage. When the thermistor gets hot, its resistance increases, and isolates the down stream portion of the power supply from the input voltage. A relay in parallel with the thermistor is closed, thus shorting the thermistor, after a preset time if the input voltage had a proper magnitude.

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Menasha, WI, United States of America

Joe Schneider