Transformer is a static electrical apparatus which converts electrical energy from higher voltage to lower voltage or vice versa without changing the supply frequency.
Distribution Transformer

Principle of Operation of Transformer

A transformer basically consists of two separate windings, called the primary winding and the secondary winding, magnetically coupled with each other through low reluctance magnetic circuit. On connecting the primary winding to an a.c. source as shown in figure below, an a.c. current I1 flows through the primary winding producing an a.c. magnetic flux in the air gap between the coil. A part of this magnetic flux links with the secondary winding inducing an a.c. voltage E2 across the secondary winding. Thus basically the voltage across the secondary winding is produced through the mechanism of mutual induction. If the output terminals of secondary are connected to a load impedance, current I2 flows in the secondary winding and the load impedance and thus electrical energy is transferred entirely from primary to the secondary through the magnetic coupling. To provide high magnetic flux linkage between the two windings, a low reluctance magnetic path is provided, typically using laminated steel core.