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MEGGER WORKING PRINCIPLE Insulation resistance quality of an electrical system degrades with time, environment condition i.e. temperatu...
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3 POINT STARTER A “3-point starter” is extensively used to start a D.C shunt motor. It not only overcomes the difficulty of a plain resis... -
A diode is a two-terminal device, having two active electrodes, between which it allows the transfer of current in one direction only....
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SERVO MOTOR This is nothing but a simple electrical motor , controlled with the help of servomechanism. If the motor as controlled dev...
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REPULSION INDUCTION MOTOR construction; THIS motor is a combinati... -
PERMANENT MANGET DC MOTOR(PMDC) In a dc motor , an armature rotates inside a magnetic field. Basic working principle of DC motor is ...
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TYPES OF DC MOTOR The direct current motor or the DC motor has a lot of application in today’s field of engine...
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PMMC METER COIL INSTRUMENT Permanent Magnet Moving Coil Instrument The permanent magnet moving coil instrument or PMMC type instrum...
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 .......
*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....