Answer / mrinal

Mainly transformer has high inductance and low resistance.
in case of DC supply inductance will not act only
resistance will act in the circuit. So high current will
flow through primary side of the transformer. for this
reason coil and insulation will burn out.

Answer / kuruvilla chacko

the induced emf will not develop due to time invariant
field.thus the winding will draw more magnetising current and
thus ultimately burn out.but a dc vlt can be aplied to the hv
winding for a short period due to better insulation props.but
ultimately it burns off

Answer / sunil

mathematical reason is that net impeadance of a system is
formed of
Z = sq.rt(X.sq + R.sq)
here X = 2*pi*f*l since
f = 0 in DC,
X also becomes 0.
hence Z also =R

which is very small in this case. When volatge applied will
be like short circuit hence the winding will burn.

Answer / sunil panchal

A transformer's primary winding presents two forms of opposition to current flow. The first is resistance, which is dependent upon the length, cross-sectional area, and resistivity of the wound conductor. The second is reactance, which depends upon the inductance of the winding and the frequency of the supply. Resistance opposes both AC and DC currents, while reactance opposes only AC current. In the case of a transformer's windings, the resistance is relatively low while the reactance is very high. When an AC voltage is applied, the reactance is sufficiently high to limit the value of AC current flowing through the winding. However, the resistance is so low that a large current would flow if an equivalent DC voltage was applied instead. This current would likely overheat the winding's insulation, resulting in its breakdown, causing a short circuit(s) which could severely damage the transformer.

Answer / naresh

we know that in case of a transformer ,the emf induced in
the secondary is proportional to the alternating flux
flowing in the primary of the transformer.
so alternating flux is produced by supplying alternating
voltage to the primary of the transformer.

if in case a dc voltage is applied ,the flux flowing
through the primary of the transformer remains constant.
therefore emf induced in the secondary is zero.

therefore no emf is induced in the coil.

Answer / techie

There will a momentary spike in seconday and then the only
current drawn from source would depend on iron losses in
the trafo

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