Direct Energy (AC – Alternating Current) Welders
The AC Welder derives its name from the fact that its output is generally a sine wave of the same frequency as the power line. It extracts energy from the power line as the weld is being made. For this reason, the power line must be well regulated and capable of providing the necessary energy. Some AC welders (including all Miyachi Unitek AC welders) include a line voltage compensation feature to automatically adjust for power line fluctuations. In its simplest form, the AC welder consists of a welding transformer that steps down the line voltage (normally between 480 to 100 volts) to the welding voltage
(typically 2 to 20 volts). The welding current that flows through the secondary of the transformer, and its connected load, is very high, ranging from 10 to more than 100,000 amps. The welding current is allowed to flow for very short periods of time, typically .001 - 2 seconds. AC welders can operate at rates up to 5-6 welds per second. AC Welding Systems are generally composed of the three elements. The Welding Transformer, the Welding Control, and the Mechanical System.
For more information regarding how to choose the right power supply for your application, read our blog: 'AC, DC, CD or HF: Which Spot Welding Power Supply Should I Use?'
And for more information about the resistance welding process read our Fundamentals of Resistance Welding.