Schematic diagram of AC welding machine The working principle of AC welding machine
The AC welding machine is a special kind of step-down transformer. According to the characteristics of the arc welding process, there is a fairly high arc ignition voltage at no-load, which is 55-80 V. During normal welding, the arc voltage drop is 30-40 V, the secondary current varies widely, generally 100-500 A, and the welding current can be adjusted. The following figure shows the principle diagram of the AC welding machine:
The transformer secondary winding N2 is connected in series with the iron core winding N3 (reactor), and the iron core has a section It is active, and its position can be adjusted by the handle to change the size of the air gap in the magnetic circuit. Under the condition that the size of I2 remains unchanged, the magnitude of the voltage drop of the winding N3 will also change. The smaller the air gap, the greater the voltage drop. Therefore, adjusting the position of the movable iron core through the crank handle also adjusts the degree to which U2 decreases with the increase of I2. When the adjustment handle is turned clockwise, the welding current increases; when it is turned counterclockwise, the welding current decreases. In addition, the primary winding of the welding transformer has a middle tap, and U1 and U2 are added to different taps, so that different open-circuit voltages can be obtained.
