Answer Posted / e venkat reddy

if u apply DC voltage to transformer,
reactive load whose formula is
Xl=2*phi*f*L
In pure dc the frequency is zero so inductive reactance is
zero and the resistance of transformer is very small ie .2
to .4 ohms. if u apply 230v DC then the current will be
230/.4= 575 amps so that it is going to burn winding of the
transformer. so we use transformer only for AC voltage.

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