:: Home Page            
 Advertise your Business Here     
Browse  |   Placement Papers  |   Company  |   Code Snippets  |   Certifications  |   Visa Questions
Post Question  |   Post Answer  |   My Panel  |   Search  |   Articles  |   Topics  |   ERRORS new
   Refer this Site  Refer This Site to Your Friends  Site Map  Bookmark this Site  Set it as your HomePage  Contact Us     Login  |  Sign Up                      
Categories >> Engineering >> Electrical Engineering


 Civil Engineering interview questions  Civil Engineering Interview Questions (3078)
 Mechanical Engineering interview questions  Mechanical Engineering Interview Questions (3289)
 Electrical Engineering interview questions  Electrical Engineering Interview Questions (13331)
 Electronics Communications interview questions  Electronics Communications Interview Questions (2363)
 Chemical Engineering interview questions  Chemical Engineering Interview Questions (416)
 Aeronautical Engineering interview questions  Aeronautical Engineering Interview Questions (77)
 Bio Engineering interview questions  Bio Engineering Interview Questions (17)
 Metallurgy interview questions  Metallurgy Interview Questions (79)
 Industrial Engineering interview questions  Industrial Engineering Interview Questions (163)
 Instrumentation interview questions  Instrumentation Interview Questions (2381)
 Automobile Engineering interview questions  Automobile Engineering Interview Questions (106)
 Mechatronics Engineering interview questions  Mechatronics Engineering Interview Questions (38)
 Marine Engineering interview questions  Marine Engineering Interview Questions (43)
 Power Plant Engineering interview questions  Power Plant Engineering Interview Questions (77)
 Engineering AllOther interview questions  Engineering AllOther Interview Questions (1196)
 Question Submitted By :: Electrical-Engineering
I also faced this Question!!     Answer Posted By  
# 1
VFD variable frequency drive..
VFD is useful in energy saving because it reduces the
motor speed as demand decreases.When the speed is reduced
the power consumption Will also reduce because ,
Power = (speed)3 {cube of speed}
For example if the speed is reduced to 80% of the maximum
value the power consumed will be reduced by 50%
Power consumed = (0.8)3 = 0.512 = 51.2%
Is This Answer Correct ?    99 Yes 8 No
# 2
VFD drive controll speed of motor by varing its freq.
But at varing freq. it have to maintain V/F ratio
constant.So for reducing speed it have to reduce freq.but
its also maintain V/F ratio constant.So automatically its
voltage is reduced.
So powre is depends on V, I & PF. So its save energy..
Is This Answer Correct ?    28 Yes 3 No
Manoj Patel
# 3
Practically VFD helps to save enery in Variable torque
loads only like Fan , pump. With affinity laws Power
proportinal to cube of speed, so if speed is reduced you
will get energy saving by using this law.

For constant torque application , if your process speed is
not full RPM but less than that say 30 Hz , then energy
saving will be there by using VFD, as you are not required
to run the motor at full speed.
Is This Answer Correct ?    13 Yes 2 No
# 4
have anybody checked the input and out current of drive if
yes then he knows that ipput current of drive is less than
that of out put current that is because of power factor
Is This Answer Correct ?    13 Yes 6 No
# 5
The real saving is observed when the VFD is used on input reference of temperature, pressure, differential pressure etc.,and this is more significant in case of Fans and Pumps, specially when we calculate the energy consumption over a certain period of time where different temperature and seasons are involved. 
Is This Answer Correct ?    6 Yes 0 No
# 6
vfd is help to reduce the power consumption and saving the life time is motor and other related pats of the pump.basically vfd is control the motor speed and its give command to the motor as a demand 
Is This Answer Correct ?    7 Yes 2 No
Tilak Guruge
# 7
Drive function is power convert,one way to onother way(by
phase convertor)So improve the power factor,
Is This Answer Correct ?    24 Yes 38 No
Itc Ltd, Snacks ,haridwar
# 8
vfd drive works almost t unity pf. so this mainly it saves
energy. if u connect motor directly it works on .8 of pf.
but vfd mainly used for better speed and torque control not
for power saving purpose
Is This Answer Correct ?    8 Yes 22 No

Other Electrical Engineering Interview Questions
  Question Asked @ Answers
derive the e.m.f equation of transformer   2
How to check the efficiency of the generator , air compressors. CIL 1
Why 5kv megger used to megger 6.6kv motor or 33kv transformer why not 500v?   1
what is the ohmic value of transformers   1
It is a three inch fan and i want it to rotate to other direction .I've tried cutting the wire and reconnecting them inverse like black to white and white to black ,but it won't start rotating when i plug it in that way.And then it works again when i rejoin the wire to the way it is. I don't know what causing the problem.Is there anyone familiar with these small mortor?Any suggestion would be appreciated.Thanks!!   1
What voltage is used in Directional earth fault relay? and why? L&T 4
how many transformer TATA 7
what is induction relay   1
We store the d.c supply...then why can't we store A.c supply???   2
How can we get a Neutral from a three phase suply? If we meet all three phases at a point to take neutral then why dont thay get sparked?   1
what is S.T?specify the range?   2
why we use the fuse in only one wire? althrough in ac current the current flows in both directions. why the neutral wire can be taken half the magnitude of phase wire while same current returns from neutral wire?   2
For more Electrical Engineering Interview Questions Click Here 

Copyright Policy  |  Terms of Service  |  Articles  |  Site Map  |  RSS Site Map  |  Contact Us
Copyright 2013  All Rights Reserved.   ::