Background: The world's leading manufacturer of plasma arc cutting equipment needed a simple, inexpensive power supply for a new hand-held cutting torch for sheetmetal.

Project: The power supply needed to have an open circuit voltage of 230 volts DC and deliver 20 amps at 100 volts DC into the plasma arc. To reduce the cost, it was desired to eliminate the high voltage igniter. This was achieved by designing the power supply to be capable of operating into a short circuit. To ignite the arc, the torch electrodes are touched together, shorting the power supply. As the electrodes are separated by gas pressure, the arc ignites automatically. During the cutting operation the supply regulates the arc current within +/- 0.5 amps. In this project Product Resources successfully met the two principal goals of producing an industrial-grade, highly-reliable product at an extremely low unit cost.

Product Resources currently manufactures these power supplies on an ongoing basis. Over 6,000 units have been shipped worldwide. Product Resources has several times achieved an annual customer award for 100% on-time delivery. This award is presented to suppliers who achieve 100% on-time delivery performance for a whole year, based on a window of -3/+0 days.

Technologies: power MOSFET switching power supply, analog circuit design, sheetmetal work, CNC machining, urethane molding

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