29 July 2017

Speed Control of Universal Motor

  • The speed control of universal motor is shown in the figure A. 
  • The single phase bridge rectifier converts alternating voltage into direct voltage.
  •  The zener diode provides constant voltage to RC circuit. 
  • The charging of capacitor is done through variable resistor R. 
  • When the voltage across capacitor becomes equal to diac break over voltage, the diac turns on. 
  • The gate terminal of SCR receives gate pulse and therefore it turns on. As soon as the SCR turns on, current passes through universal motor. 
  • The discharging of capacitor is done through diac and gate cathode circuit. The speed control of DC motor is done through variable resistor R. 
  • If the variable resistor R sets at higher value, the charging rate of capacitor decreases and firing angle increases. 
  • This will result in speed of universal motor decreases. There are others several method to control speed of universal motor.

speed control of universal motor

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