Stator voltage control methods - motor control , Electrical Engineering

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.

 

Posted Date: 4/3/2013 2:34:43 AM | Location : United States







Related Discussions:- Stator voltage control methods - motor control , Assignment Help, Ask Question on Stator voltage control methods - motor control , Get Answer, Expert's Help, Stator voltage control methods - motor control Discussions

Write discussion on Stator voltage control methods - motor control
Your posts are moderated
Related Questions
What are operations performed on data in 8085 The various operations performed are Store 8-bit data Perform arithmetic and logical operations Test for conditio

Illustrates about the power dissipation management in embedded system? Power Dissipation Management a. Clever real-time programming through Wait and Stop instructions b.

1 diagram basic layout of a simple transformer

i need to rewrite 24 pages of engineering research.

Fourier Deconstruction Find the Fourier series as far as the third harmonic, to represent the periodic function y, given by the values in the following table.

Explain FET amplifiers? Just like the BJT amplifiers, FET amplifiers are constructed in common-source (CS, analogous to CE), common-drain (CD, analogous to CC), and common-gate

State and explain three factors upon which the induced electromotive force depends

Q. What is Pinch - off voltage?  The reverse bias is relatively large near the source. As a result, the depletion region intrudes into the channel near the drain, and the effec

What are advantages of segmentation ? However because the segment register is 16 bit broad and the memory requires 20 bits for an address the 8086 appends 4 bits segment reg

Simplified operation: Figure: Simple circuit to show the labels of a bipolar transistor. The essential value of a transistor comes from its capability to make use