Stator voltage control methods - motor control , Electrical Engineering

Assignment Help:

Stator Voltage Control Methods

By  controlling  the applied voltage  the speed  of an  induction motor  can be  controlled. Since  the output  torque of 3-? induction motor  is given by T sI/2 and current  is proportional  to voltage . therefore  as voltage  is reduced to reduce speed  for the  same current motor  develops  lower torque.

If  stator  copper  loss core  loss and friction and wind age  loss are  ignored then motor  efficiency  is given by

Η = Pm /Pg = (1-s)

This  equation shows that the  efficiency  falls  with decrease in speed. The speed  control  is essentially obtained by dissipating a portion of rotor  power in  rotor resistance. Thus  not only  the efficiency if low the power dissipation occurs  in rotor itself which may  overheat the rotor.  Variable voltage for  speed  control  is obtained  using  ac voltage  controllers as shown  in figure.

 By  changing the  conduction  period of the SCR  the magnitude  of stator  voltage  can be controlled from zero  to full supply voltage. Thus  we can obtain the speed variation.  But this  methods is suitable for small and medium  size induction motors because  supply  current contains harmonic components. The  another disadvantage of this method is that a heavy current  flows through  stator if speed is reduced therefore  there may be  undue heat  generation is  stator windings.

 


Related Discussions:- Stator voltage control methods - motor control

Difference between photography & holography, 1.       In ordinary photograp...

1.       In ordinary photography, each part contains information of the original object separately and in case some part of the object is destroyed then the information of that par

Need for modulation recognition - software defined radio, Need for Modulati...

Need for Modulation Recognition There are so many communication signals all available with different types of modulation and different frequencies. It is necessary to identify

Need of microphone in telephone hand set, Q. Need of Microphone in telephon...

Q. Need of Microphone in telephone hand set? Microphone: For all practical purposes, microphone is transmitter for telephone. The microphone converts acoustical signals in the

Purpose of control word written to control register in 8255, What is the pu...

What is the purpose of control word written to control register in 8255? The control words written to control register state an I/O function for every I.O port. The bit D7 of t

Show advantage of digital control system over analog system, Q. Show Advant...

Q. Show Advantage of digital control system over analog system? Sampled data and digital control offer several advantages over analog systems: • More compact and lightweight

Distribution transformers, Distribution Transformers 1. Augmentation/...

Distribution Transformers 1. Augmentation/Addition of Distribution Transformers Distribution transformers have to be augmented by installing additional transformers or in

Electric machinery fundamentals, Ask qu1. If the resistor Radj is adjusted ...

Ask qu1. If the resistor Radj is adjusted to 175O what is the rotational speed of the motor at no-load conditions? 2. Assuming no armature reaction, what is the speed of the motor

What is memory mapping, What is memory mapping? The assignment of memor...

What is memory mapping? The assignment of memory addresses to several registers in a memory chip is known as memory mapping.

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd