Answer / nithin shaju

Applying DC power to a transformer will not step up/down
the voltage,since the current reaches its peak within
milliseconds and remain constant.Therefore no induction
happens.So secondary voltage is induced only during the
current growing period (millisec).After that as long as
there is no fluctuation, sec voltage will be 0.
There is no
problem in connecting dc power suppply to a
transformer.Only winding resistance is taken into
account.But if the current is too high there is a chance of
burning the insulation.

Answer / uma

When the transformer is used with dc excitation, flux rises to the point where magnetic saturation occurs, causing a large increase in magnetizing current & overheating of the transformer. therefore they operate in ac.

Answer / venkat

we cannot apply DC power to transformer as it is an ac machine and on applying DC power the windings of the transformer gets short circuited due to unidirectional flow of electric charge

Answer / ahmed

We can apply dc supply to transformer, but here impedance
is only resistance in casof DC.large amount of current will
flow through the promary windings depending on the
magnitude of primary voltage applied.Secondary will not
induce any voltage.

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