:: 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 (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 (1207)
why the motor running in delta connection ? it can be in star?
 Question Submitted By :: Electrical-Engineering
I also faced this Question!!     Answer Posted By  
# 1
all the above is not seems to be correct.. the real thing
is in star IL=Ip so we are going for star at the time of
starting. after the machine attains rated speed we are
changing into delta becuase the machine cannot develop
rated TORQUE of the motor in star but it can develop in
delta since in delta VL=VP. that's why its changed to delta
instead of running in star. V is directly proportional to
flux is inturn proportional to torque.
Is This Answer Correct ?    63 Yes 5 No
# 2
Because the voltage in star connection is Vph=VL/square
root of three.
But in delta connection Vph=VL.
So in star connection is only for starting a motor.
But to run a motor through a delta winding. Becaus then
only full voltage given to motor and it will run in full
Is This Answer Correct ?    48 Yes 24 No
Silamparasan P.
# 3
When a delta motor is connected in star, the voltage across
the windings is reduced by the square root of three
resulting in reduced flux in the iron, this will reduce the
magnetizing current, and will also reduce the torque
capacity of the motor
Is This Answer Correct ?    21 Yes 3 No
Madhav Agrwal
# 4
The type of connection in which the motor is running
continiously depends upon its design and the type of
application it is used...

there are motors designed for continious star opearation...

But the basic thing is star is preferred for starting and
delta is preferred for runnnig owing to design as well as
economic feasibilities...
Is This Answer Correct ?    14 Yes 5 No
# 5
Simple 3 phase motors can be connected in either STAR or
In star the maximum power is reduced but the starting
current is lower than for Delta
In Delta the motor gives maximum power but the starting
current is often too high and the overload trips out.
To overcome this a star/delta starter is fitted
All 6 wires from the motor windings are connected to the
starter and the starter functions are as follows :-

When start button is pressed the motor is automatically
connected in star and the start current is acceptable. At
the same time a timer is initiated and after a
predetermined time the starter automatically changes from
star connection to delta. The motor now runs in Delta until
switched off.

This is a fully automatic starter, many years ago manual
changeover star/delta starters were more common.
Is This Answer Correct ?    13 Yes 5 No
# 6
Motor can be connected in delta as well as star.

In delta connection the maximum power that motor can give
is motor rating.ex 15 kw motor 15kw power.

In star connection the maximum power motor can give is
(motor KW * 1/3). Now the motor is derated.

Also note that if your motor 50% only loaded then the motor
winding can be connected in star instead of delta. This
will give you power saving. Also take care that always load
on motor is less than 50% or else motor winding will get
burnt. For more clarification mail me on
Is This Answer Correct ?    2 Yes 0 No
Shaji Samuel
# 7
Motor running with star or delta depends upon the design,the same is given in the name plate.The reason for most of the motors are in delta is to limit the starting current by turn ON in star connection & than converting to delta connection to get the rated speed & torque. Where as it is not possible if the motor design is star. But now we get more of star connection design motor which are VFD & soft starter application. 
Is This Answer Correct ?    2 Yes 0 No
# 8
Its a matter of torque which is low in star because of reduced voltage at
winding and at designed load star connected motor get stopped due to
insufficient torque. More you have to see motor characteristic at diff.
Is This Answer Correct ?    0 Yes 0 No
Samir Vyas
# 9
motor running in delta it can be in star beacuse star
connected motor has taken voltage root three times and
current high that the cost is high threrfore motor runngin
in delta but in industres star motor connection also
working its motor rating low kw.
Is This Answer Correct ?    4 Yes 8 No
# 10
speed is depends on frequency and no. of poles. 
Is This Answer Correct ?    26 Yes 31 No

Other Electrical Engineering Interview Questions
  Question Asked @ Answers
What is primary distribution and secondary distribution of ac power?   3
what is the basic principle of the alternator ????   2
Input power is 380 - 450 V but with 45 - 55 Hz frequency - desired output is 415 V and 50hz with 1% variation permissible. CVT / Servo dont stabilize the Frequency - what is best solution?? IOCL 7
Is it necessary to seperate the DG earth grid with Electricity Board earth grid for protecting the DG set. if yes why? BARC 2
Is ground earthing required for neutral conductor of a prime mover ie DG set?   1
what will happen if the bus PT fuses are accidently removed from the circuit in 6.6kV feeder?   1
when a airgap of the induction motor gets larger does it draw more current ??? does it power factor gets lower?   3
How to model "to find the cube root of the given number" in Matlab Simulink ?   1
We have 2 11kv/433v transformers for 2saperate acb for mv panels and 1 bus coupler acb. Suppose Iíll close bus coupler what will happen or it will be share the load. Please suggestion and any modification required.   1
What is the purpose of Vector Group in transformer? ThyssenKrupp 1
please explain power factor in simple words.....   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.   ::