Frequency

The rate at which alternating current makes a complete cycle of reversals is termed frequency. Electrical power in Australia is delivered as 50 cycles per second, or to use its proper term 50 hertz (Hz). This means there are 100 reversals of current flow directions per second.

An oscilloscope representation of a 50Hz wave compared with a 60Hz wave

The mains frequency input to an AC welding machine and other electrical equipment in Australia is 50 Hz. In North America, 60 Hz is used. This was also the frequency of the welding current when transformer welders were used. Inverter welders are controlled by a microprocessor allowing the welding frequency to be changed.

 

Frequency has major effect on welding arc performance. As frequencies go up, the arc gets more stable, narrows, and becomes stiffer and more directional. The figure below shows 50 and 60 Hz sinusoidal current waves.

 

Reference: Miller – TIG Welding Handbook

Scroll to Top