Spurious triac firing pulse suppression in welding circuit - by having high ohmic resistor applying potential to triac anode

摘要

In a control circuit for resistance welding rigs, the control triac is connected to a solenoid valve for the supply of air through a standby switch. Closing of the standby switch often causes the triac to respond and fire even when no control voltag ehas been applied to it. This can be caused by a voltage surge, caused by the closure of the standby contact. To remedy this, a high-ohm resistor is connected in parallel to the series connection of standby contact and solenoid valve. This applies to the anode of the control triac a voltage which suffices to prevent its firing by a voltage surge, caused by closure of the standby contact.