Several manufacturers have developed power supplies for hot wire GTAW welding. Some use sine wave AC for heating the wire, some use square wave and even DC. The Arc Machines, Inc. Hot Wire Power Supply Model 501 has controls for (heating) current and (hot wire) voltage. The standard mode of operation for the Model 501 is Constant AC Voltage (0 - 10 Volts), but Constant Current mode (Max output 250 Amps) is also available. The Model 501 implements advanced technology. AC current is used to minimize magnetic interference (arc blow). The AC current of the Model 501 is very close to a true sine wave. To control the hot wire power the voltage is sensed where the power cable is attached to the guide tube. By measuring the voltage at the guide tube, the effects of cable length (voltage drop) are controlled.
The accuracy of true RMS provided by these measurements make it possible to duplicate production conditions from one set-up to the next with excellent repeatability of process.