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STARTING OF SLIP RING MOTORS

         STARTING OF SLIP RING MOTORS

*At starting the handle of resistance is  set in the OFF position so that maximum resistance is placed in each phase of the rotor circuit . this reduces the starting current and the same time starting torque is increased.
*As the motor pick up speed ,the handle of resistance is gradually moved in clockwise  direction and cuts out the external resistance in each phase of the rotor circuit .when the motor attains normal speed ,the change-over switch is in the ON position and the whole external resistance is cut out from the rotor circuit .......

ELECTRONIC AC TO DC CONVERTERS

                           TYPE OF POWER ELECTRONIC

  • DIODE RECTIFIER

  • AC TO DC CONVERTERS

  • DC TO DC CONVERTERS

    DC TO AC CONVERTERS

  • AC TO AC CONVERTERS

  •                                   DIODE RECTIFIER

              A diode rectifier circuit converts ac input voltage into a fixed dc voltage.The input voltage may be single phase or three phase.Diode rectifiers find wide use in electric traction,battery,electroplating,electromechanical processing,power supplies,welding and uninterruptibles power supply(ups) systems 

    AC TO DC CONVERTERS

     

                       

                These converter constant ac voltage to variable dc output voltage.These rectifiers  use line voltage for their commutation,as such these are also called line-communited  or   naturally-commutated ac to dc converters.

             Phase -controlled converters may be fed from 1-phase or 3-phase sources.These are used in dc drives,metallurgical and chemical industries,excitation system for synchronous machines ete.

    DC TO DC CONVERTERS 

     

            A dc chopper converts fixed dc input voltage to a controllable dc output voltage.The chopper circuit require forced or load,commutation to turn-off the thyristors.For lower power circuits,thyristors are replaced by power transistors.

               Classification of chopper circuit is dependent upon the type of commutation and also on the dirction of power flow.Chopper find wide applications in dc drives,subway cars,trolley trucks etc..

    DC TO AC CONVERTERS

     


                 It is called as inverters.An inverter converts dc voltage to ac variable voltage.The output may be variable voltage and variable frequency.These converters use line or load or forced commutation for turning-off the thyristors.

                  Inverters find wide use in induction motor and synchronous motor drives,induction heating,UPS,HVDC transmission etc...

                        AC TO AC CONVERTERS

     

    These convert fixed ac input volage into variable ac output.

    application:lighting control,speed control of fans etc....                  

     

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