Answer / guest

The answer to this question depends upon the type of
motor.The excitation means supply needed to establish the
working flux.

AC motors

3 phase Synchronous Motor
Cannot be started without excitation.Because the magnetic
locking(which is necessry for continous rotation) between
rotating stator field(created due to balanced 3 phase
supply to stator) and rotating rotor field(rotor is being
rotated intially by external means) is not possible without
excitating the field.
3 phase Induction Motor
There is no concept of excitation in this motor.Motor runs
on the principle of induction,So only 3 phase stator
current and rotror bars shorted at end is needed.There is
no need of excitation on rotor bars.
1 phase Induction Motor
There is no concept of excitation in this motor.Only supply
is needed to Stator winding(don't confuse this with
excitation.This is different from excitation).So motor will
run with supply connected to stator.However the stator
winding is splitted into two parts for providing phase angle
(which is necessary for rotation) bewween current flowing
through main and auxiliary windings.

DC motors

AC supply is given to stator winding which is converted
into DC by means of commutator.Field winding, which is
connected in series in case of series motor,
in parallel in case of shunt motor or
in combination in case of compound motor.
In all the three cases excitation is needed to run the
motor.

conclusions:

1)some AC motors(Induction motors: 3 phase and 1 phase) can
started without field where as some AC motor(3 phase
synchronous motor) cann't be started without field.
2)DC motors cann't be started without excitation.


Author:arbelectbit@yahoo.com

Answer / niranjan

no we cant start any motor without excitation... because the
word excitation implies the field creation, which is must to
produce a torque in motor.. if we take any motor directly or
indirectly exitation is produced first and then only motor
starts running, even in i/m also first excitation(rotating
flux) is created then only motor starts rotating

Answer / karthik

No,in dc it short circuits the armature,no back emf is
created.In ac in alternator high magnitising curent flows
in stator.

Answer / sandeep

u can start a induction motor without field excitation...

Answer / manikanta..{munna} geethanjali

the word excitation means to build a conducter into an
elecromagnet. there fore the other subtitute is 2 use a
permanent magnets.

Answer / singhashish35

yes

i wanna know that star point in transformer becomes as a neutral on secondary side now tell me that how is that possible?because if joit the all three winding ends with each other it can b short circuited.dut it doesn't.WHY?pls Answer me in brief.thanks alot

1 Answers  

What is the output of below program? #include <stdio.h> int main() { int p,q; for(p=1,q=1;p<7;p++) { printf("%d%d__",p,q); } return 0; } Answers- 1. 17__27__37__47__57__67__ 2. 11__21__31__41__51__61__ 3. __11__21__31__41__51__61__ 4. Compilation error

1 Answers  

what is cogging in motors?

1 Answers  

WHAT IS MEANT BY BTU OF AIR CONDITIONERS.

2 Answers  

1.Difference between vcb and Acb and partes. 2.Difference between STS and ATS.

2 Answers  

define excitaton voltage and excitation current?

2 Answers   Allied Group,

they conducted technica for 1 hour..i also managed..they selected 5 boys and only one girl,myself got wait listed.whether they would call or not

2 Answers   MAHINDRA,

In the diesel generator wihch type of power we can get it ? Like AC / DC

2 Answers   Aditya Birla, Indian Steel, PTPS,

what is necessity of using isolation transformer?

4 Answers   NTPC,

no of rotrs poles in salient pole synchronous machine

3 Answers  

in short circuit. test of a transformer 5 to 10% ofvrated voltage is used why??? if we use rated voltafe then what will be?

1 Answers  

Why space heater is required for each verical bus bar chamber? if one space heater is adequate or not for anti condensation?

0 Answers