Welding machine no-load automatic stop circuit

During the welding process, welders often have to do some preparation work, causing the welding machine to run without load and wasting a lot of
electric energy. In order to reduce this loss and make the welding machine have power when it is working and cut off the power when welding is stopped, a bidirectional thyristor is used as the power switch of the AC welding machine
. The bidirectional thyristor can conduct under positive and reverse voltages, and the gate can be triggered under positive and negative pulses, so it can be used as
the AC switch of the welding machine. The circuit features are simple, economical, easy to maintain, and reliable in operation.
    The picture shows the power-saving control circuit diagram of the electric welding machine. The main circuit is composed of the bidirectional thyristor VTH, the fuse FU, the welding machine transformer T, the switch
SB1, etc. The control circuit is composed of the gate G of the thyristor VTH through the current limiting resistor and the micro switch SB2. When you want the welding machine to work
, close the switch SB1 and the power is turned on, but VTH is not turned on. The operator holds the welding gun and closes the microswitch SB2 installed on the handle of the welding gun.
While positive and negative voltages are added to VTH, there are also forward and reverse AC trigger signals on the gate G, which turns on the main circuit. When the operator finishes welding
a weld, he needs to pause, relax his hands slightly, and the micro switch SB2 is turned off. When the AC voltage of the main circuit crosses zero, VTH is turned off, thus
cutting off the power supply and eliminating no-load loss.