Transformer

The main advantage of alternating currents over direct currents is that, the alternating currents can be easily transferable from low voltage to high or high voltage to low. Alternating voltages can be raised or lowered as per requirements in the different stages of electrical network as generation, transmission, distribution and utilization. This is possible with a static device called Transformer. The Transformer works on the principle of mutual induction. It transfers an electric energy from one circuit to other when there is no electrical connection between the two circuits.

The principle of mutual induction states that when two coils are inductively coupled and if current in one coil is changed uniformly then an e.m.f. gets induced in the other coil. This e.m.f. can drive a current, when a closed path is provided to it. The Transformer works on the same principle. In its elementary form, it consists of two inductive coils which are electrically separated but linked through a common magnetic circuit. The two coils have high mutual inductance.

One of the two coils is connected to a source of alternating voltage. This coil in which electrical energy is fed with the help of source is called primary winding (P). The other winding is connected to load. The electrical energy transformed to this winding is drawn out to the load. This winding is called secondary
Core winding (S).  The primary winding has (N) number of turns while the secondary winding has N₂ number of turns. When primary winding is excited by an alternating voltage, it circulates an alternating current. This current produces an alternating flux (ø) which completes its path through common magnetic core, thus an alternating, flux links with the secondary winding. As the flux is alternating, according to Faraday's law of an electromagnetic induction, mutually induced e.m.f. gets developed in the secondary winding. If now load is connected to the secondary winding, this em.f. drives a current through it. Thus though there is no electrical contact between the two windings, an electrical energy gets transferred from primary to the secondary.

Questionnaire:

• What is Transformer? How it works.