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

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