ALLInterview.com :: 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                      
Google
   
 
Categories >> Engineering >> Electrical Engineering
 
 


 

 
 Civil Engineering interview questions  Civil Engineering Interview Questions (3157)
 Mechanical Engineering interview questions  Mechanical Engineering Interview Questions (3309)
 Electrical Engineering interview questions  Electrical Engineering Interview Questions (13489)
 Electronics Communications interview questions  Electronics Communications Interview Questions (2396)
 Chemical Engineering interview questions  Chemical Engineering Interview Questions (424)
 Aeronautical Engineering interview questions  Aeronautical Engineering Interview Questions (77)
 Bio Engineering interview questions  Bio Engineering Interview Questions (17)
 Metallurgy interview questions  Metallurgy Interview Questions (80)
 Industrial Engineering interview questions  Industrial Engineering Interview Questions (166)
 Instrumentation interview questions  Instrumentation Interview Questions (2409)
 Automobile Engineering interview questions  Automobile Engineering Interview Questions (109)
 Mechatronics Engineering interview questions  Mechatronics Engineering Interview Questions (38)
 Marine Engineering interview questions  Marine Engineering Interview Questions (45)
 Power Plant Engineering interview questions  Power Plant Engineering Interview Questions (82)
 Engineering AllOther interview questions  Engineering AllOther Interview Questions (1211)
Question
what is the difference between induction and synchronous 
motor?explain in simple words?why 3 phase motor is given 
preference over single phase motor.
 Question Submitted By :: Electrical-Engineering
I also faced this Question!!     Answer Posted By  
 
Answer
# 1
Following are the differences between an induction and
synchronous motor:
1. An induction motor is singly excited motor (i.e.)power
supply is fed only to the stator. On the otherhand, a
synchronous motor is doubly excited (ie) stator must be
supplied from an ac source while the rotor is supplied from
a dc source.
2. An induction motor can only run at speed less than the
synchronous speed. While a synchronous motor can run only
at synchronous speed.
3. A 3phase induction motor is self starting while the
synchronous motor is not self starting (i.e.)it has to be
driven by another motor upto or near synchronous speed
before being pulled-up by the synchronously rotating flux
(magnetic locking).
4. In an induction motor Stator has field windings and the
rotor is the armature. In a Synchronous Motor, the field
winding is the Rotor while armature is the Stator

The relationship between frequency and speed is given by

f=pn/120 ; where f = frequency, n = speed,
p = no. of poles

For a 4 pole motor supplied from 3 phase 50Hz power supply,
the speed would be 1500rpm. This speed is called
synchronous speed. This means that the speed of induction
motor will always be less than 1500rpm whereas the
synchronous motor can run only at 1500rpm.

3phase machines are used for high power applications
usually of about 1kW whereas 1phase motors are used for
fractional horse power applications.

3phase induction motors are self starting whereas 1phase
motors are not self starting but can be made self starting
by temporarily started as 2phase motor having two windings
using capacitors for one phase.
 
Is This Answer Correct ?    41 Yes 1 No
M S Kumar
 
Answer
# 2
The main diffrence betwwen synchronous Moter & Induction
motor is.(On Designing Basis)..In the inductoin motor field
winding is on Stator & armature winding is on Rotor While
in Synchronous Motor the Field winding is on on Rotor &
Armature winding is on Stator
 
Is This Answer Correct ?    42 Yes 13 No
Tarkeshwar Mall
 
 
 
Answer
# 3
the induction motor run at lower than synchorous
speedsynchorous synchorous speed.
 
Is This Answer Correct ?    37 Yes 14 No
Amirtha
 
Answer
# 4
Synchronous motor : doubly excited (DC to the rotor , AC to the stator), not self starting , high PF (used as capacitor bank) , unity or leading PF , high efficiency (low inrush current) , Shorter operational life compared to the induction motor (brushes).

Induction motor : singly excited (AC to the stator), self starting , low PF , lagging PF , low efficiency (high inrush current) , longer operational life compared to the Synchronous motor (no brushes).
 
Is This Answer Correct ?    11 Yes 0 No
Mohammed Subhi Assaf
 
Answer
# 5
Synchronous motor working as a leading power factor and
induction motor working lagging power factor. synchronous
motor used for power factor improving.
 
Is This Answer Correct ?    12 Yes 2 No
Mukesh Kumar
 
Answer
# 6
the diffrence is comes at their speeds.
IM runs at iess than synchronus speed
sm runs at synch speed
 
Is This Answer Correct ?    13 Yes 4 No
Upendra
 
Answer
# 7
IM is a self start motor while synchronous motor is not
self start.
 
Is This Answer Correct ?    9 Yes 1 No
Shanawaz
 
Answer
# 8
induction motor has self starting torque. synchronous motor
has no self-starting torque therefor some external means be
used to start it.
 
Is This Answer Correct ?    7 Yes 1 No
Sharvan Kumar Saini
 
Answer
# 9
main difference is that why IM doesnt run at synchronous speed?
coz of the slip.
ns= 120F/P
slip=(ns-1)/ns at synchronous speed

at standstill condition slip (%)will be 1
so as the slip increases speed of the motor decreases.

slip in the case of IM at standstill condition is 1. so
obiviously IM wont run at synchronous speed.
 
Is This Answer Correct ?    6 Yes 1 No
Hrishikesh
 
Answer
# 10
synchronous motor is also for power factor
improvement.while induction motor not
 
Is This Answer Correct ?    5 Yes 0 No
Suraj
 

 
 
 
Other Electrical Engineering Interview Questions
 
  Question Asked @ Answers
 
THE 40 MW OF POWER FOR 220 V III PHASE POWER CONNECTION REQUIRES HOW MANY KVA POWEER REQUIREMENTS Chartered-Accountant 7
How to find the length of a Xlpe cable required to transmit 3mva load at 22kv.   1
what is the technical term when and alternator's prime mover fails. DVC 2
I NEED RRB CHENNAI (JE ELECTRICAL) QUESTION PAPER FOR LAST 5 YEAR AND I NEED RRB (JE ELECTRICAL) SYLLABUS.PLEASE SEND MY E-MAIL joo28_eee@yahoo.co.in Hindustan-Unilever-Limited 10
how we masure a cuurrent?   5
why the transmission side of the generating transformer is always star??   4
sometimes, eventhough the HV side of the transformer is opened there is a voltage in LV side .How is it possible?   4
SAY CORRECT DEFINITION... WHAT IS EDDY CURRENT LOSS? WHAT IS HYSTERESIS LOSS?   4
one cable insulation resistance 200 mega ohm. how find 250 meter cable resistance. NTPC 2
how can findout cable fault Location only useing MEGGER   3
which is more dangerous A.c or D.C?   25
what is the difference between earthed cables and unearthed cables Bhel 2
 
For more Electrical Engineering Interview Questions Click Here 
 
 
 
 
 


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

ALLInterview.com   ::  KalAajKal.com