Answer / electrockers

transformer is based on the principal of electromagnetic
induction.
when flux related to a coil changes with time it produces
voltage across da coil ..same funda used here ...when AC
current flows through da transformer coil it produces
varying magnetic field tat magnetic field interact with da
secondary coil of transformer and produces voltage
...whereas in case of DC there is no magnetic field produces
in coil ....

Answer / minal verma

In a transformer, when ac current flows then due to its
frequency an emf is induced in it due to electromagnetic
induction.
But when a DC current flows through the transformer, then
no emf is induced in it because there is no frequency in dc.
Thus dc current is not used in transformer.

Answer / a

dc current has no frequency

Answer / santosh jadhav

1) transformer works on the principle of Electromagnetic
Induction when Ac supply is fed to Xmer due to Alternating
nature it Induces EMF in the Secondary winding.
2) When Dc supply is fed to primary as frequency is 0 in DC
supply No Emf s induced in Secondary & total input power
loss takes place in Core only Core burnt out Finally.

Answer / sunny

transformer works on two principals
1 elctric current produces magnetic field
2 varying magnetic field induces voltage across the
terminals of wire..
so if there will be no change in current as in DC
no magnetic field will be produced and neither the current
will be induced in the seconday...transformer action will
not take place..

Answer / karthikeyan

That is true there is no Back EMF also. while if we inject
DC in a transformer. and if doing so the transformer will
act like a short circuit to DC. so that the coil will be burnt.

Answer / karthik & chandrashekar fr

because the ac supply has a frequency but dc supply has
there is no frequency.

Answer / kamaraj

Transformer is working based on the principals of
Electromagnetic induction when A/c supply applied in the
primary wdg which induces EMF in the Secondary wdg.

While applying DC supply in the primary wdg, it will burnt
if it is Step up transformer, because it acts as Series
motor and it takes high current. and there is no back EMF
induced in the Tr sec. wdg.

Answer / michael j.

In an a/c transformer, because of the alternating current
in the primary coil, a current is induced in the secondary
coil because the wires in the secondary cut acroos the
magnetic field lines of the primary coil.(magnetic
inductance). a d/c current on the other hand does not have
a collapsing magnetic field because its current is
constant. therefore, no collapsing magnetic field means no
induced current.

Answer / koppu chowdaiah

Transformer is working based on the electromagnetic induction. It is static device.If we apply dc voltage to the transformer the relative motion b/w the core & flux is zero.Hence no emf will be induced.And at the same time the reactance of the tr is zero.so it acts as short circuit hence high current will flow. hence the transformer primary wdg is burnt.but the secondary wdg is safe.

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