DC welding machine no-load automatic power-off circuit

Circuit working principle: This device consists of signal power supply, transistor amplification and control circuit
. The capacitors C and C3 in the line are connected in parallel with the main contact of the AC contactor JC and in series with
the primary coil of the rectifier transformer ZB. When the switch K is closed, the normally closed
contact J of the time relay is energized and closed, and the AC contactor JC is energized and closed, making the welding machine temporarily charged. After the time
relay SJ passes with a delay of about 10 s, its normally closed contact is disconnected, the contactor JC coil
loses power, and the welding machine is in a power-off state.