Answer / shiva

the transformer Works on variable flux(A.c. flux, rms value
is const) if we give dc input the flux generated is
stationary and cannot devolp the induced emf in primary(E1)
&secondary(E2)...so there is no opposition of current flow
in primary & Secondary(since E1,E2=0).....there fore high
currennt passes through windings ...so that wdg may damage
to such high currents...

Another way of explination
transformer core material works on some const magnetic flux
density..in some range... but if give dc in put its
frequency is zero. So
B=V/F ===)B=v/0 ===)B~~ infinate value...requred such
material is not possible practically

Answer / anurag sankar sengupta

transformer mainly works on the principle of varying flux and minimum reluctance path.
now when we connect the source to a dc supply the magnetic flux linking the core become stable to a value. so the transformer will gain some amount of heat and be burned if the voltage becomes hi gher than the normal.

Answer / jaheerabbas

in transformer primary and secondary windings are behaves
like inductor in initial stage (t=0)sec, inductor impedance
formula is 2*pi*F*L, so F=0 means DC then no inductor
effect,no inductor effect then no Flux,no EMF nothing....so
only we are not using DC signal in transformer

Answer / pradyumna chandra panda

In transformer there is verry small resistance in primary winding it stand with ac supply because itself an inductive load ( leg the current). but there is no possible of legging current in dc supplly if we give it in transformer the primary winding will be burn out due to small resistance of primary winding and no emf will induced in secondary winding due to failure of mutual induction.where flux linkage is not possible.

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