27 July 2017

Resistance welding using Triac - Diac circuit

  • The power circuit for the resistance welding using TriacDiac is shown in the figure A. 
  • The current passes through transformer primary winding when Triac is turned on. As soon as the alternating supply is on, the charging of capacitor is done through path AC supply – R – C. 
  • When the voltage across capacitor becomes equal to diac break over voltage, the diac turns on. 
  • Now the gate of the Triac gets pulse and resulting Triac turns on. The current starts to flow through primary winding of the transformer.
  • The control of current is done by variable resistor R. The firing angle of the Triac increases when the setting of variable resistor is made at higher value. 
  • The current passes through transformer primary winding decreases as the firing angle of the Triac increases. 
  • The transient voltage generated due to switching on the Triac and this voltage may damage the transformer primary winding. 
  • The thyride resistor is connected across transformer primary winding in order to suppress transient voltage. 
  • The resistor of the thyride resistor decreases as the voltage increases and this will protect the transformer primary.

resistance welding using triac and diac

You may also like :