Why ca you not use a transformer on a DC circuit?

Answer 1

Transformer can not be connected to DC supply because of the reason described as below:

In case of AC Supply to the transformer, Current flows through the primary winding when the primary winding is given V1 voltage. So the alternating flux is produced in the core. This flux links with the winding and the emf E1 is used in the winding, which lags V1 by 180 degree. So only magnetizing current is drawn from the supply ( at no load ), whose value is very less.

Now if the primary winding is connected to the DC supply, unidirectional flux is produced in the core, which does not induce emf in the primary winding. So the current is limited by the resistance of the winding only. Now the resistance of the winding is very less so it takes large current. So the fuse blows off as soon as the DC supply is given. If the thick fuse wire is used, the primary winding burns out.