Answer / sirisha

if dc supply is given to transformer there will be no
change in the flux with time.so there is no emf induced in
the primary and secondary windings.and hence tranformer
action will not take place.

Answer / jaya bharath reddy

generally, transformer o/p is come by mutual induction i.e,
flux produced in primary coil causes the flow of current in
secondary coil. mainly, flux is produced by time varying
fields i.e, ac signal since the ac signal is time variant
but dc signal is time invariant signal it is constant all
the values of time . so, flux is not produced in the
primary coil consequently no flow of current in secondary
coil.

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ALL THE BEST!!!!!!!

Answer / sagaya prabhu

Transformer is mutual induction device , No induction
Effect is acted in D.C Supply . & if you give a D.C supply
to transformer windings the windings will be burn out ,
because of static EMF is produced by D.C Supply.

Answer / jinen dand

Transformer works on Mutual Induction principle. Mutual
induction principle works only on Ac suppy.
So dc power cannot be used in transformer.
If dc power is supplied to transformer following things
will happen
1. if winding resistance is low then according to ohm law
high current will flow through winding which will cause
high temp rise if supply sustains then winding may get
damage.
2. If winding resistance is high compare to applied voltage
then only contant flux around winding will be there.


It is very good question..........

Answer / zahid ali

the basic principle of transformer operation is mutual
induction & there is no mutual induction in DC

Answer / syed shareef

the nessacity to produce emf there must be change in flux.
in ac the sine wave changes with the time so resulting flux
also have time change due this emf produce.
but in dc there is no change in flux or there is no change
in time with wave so it unable to produce emf with it self
if any other means you are going to rotate or too fro
motion then you can produce emf
the law is used is fredays law of electromagnetisum

Answer / rajesh babu

we cant use dc power in a transformer.there are two main
reasons supporting above statement
1)there will be no action of transformer(as it works on
principle of mutual induction)
2)winding of the transformer acts as inductor&it acts as
short circuit for DC
inductive reactance XL=2*PI*F*L
DC HAS ZERO FREQUENCY so XL=0,HENCE IT ACTS AS SHORT CIRCUIT
Deu to this winding of the transformer may burns out.

Answer / malghani

ac power suply cause indused emf and flux due to magnatic
induction.but in dc case there is no cut off magnatic line
and no flux perodused.so we use AC power supply.

Answer / ilaya

dc power can't used in transformer. because dc power is
unidirectional.basicaly emf induced in two way,
1).condctor is stationary and flux is rotating.
2).flux is stationary and condctor is rotating.
so dc supply give to transformer,it produce stationary
magnatic field and also conductor is stationary.so no emf
induced in secondary.if dc supply maintain to the
transformer heat is produced(transformer windings are low
resistance).finaly windings are burn.so transformer is not
working in dc power.
(incase ac supply flux is rotating(rotating magnatic field)
and conductor is stationary.so emf is produce in secondary
winding)

Answer / subba lakshmi

DC current should not be given to TFR bcoz in it frequency
is zero due to which the reactance which is given by
2*pi*f*l will be zero hence the entire voltage applied is
opposed only by the resistance fo the wire which is nearly
zero hence current produced will be high as v=I*R hence due
to which there are chances of melting wire.

at the time of starting back emf of a motor is zero.so how can it will start to run??

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