Transformer - Component of Power Distribution System
A transformer is an electrical device that transfers power from one circuit to another without modification in frequency. The reason of a transformer is to convert one AC voltage to another AC voltage. A transformer comprises two or more coupled conducting coils (windings) that are wound on common laminated core of a magnetic material like as iron or iron-nickel alloy. These are known as primary and secondary windings.
The alternating current in the primary winding creates an alternating magnetic field in the core just as it would in an electromagnet. The secondary winding is wrapped around the similar core. The changing magnetic flux (magnetic field per unit area per unit time) in the basic winding induces alternating current of the similar frequency in the secondary winding. The voltage in the secondary winding is controlled through the ratio of the number of turns in the two windings.
If the primary and secondary windings have the similar number of turns, the primary and secondary voltages will be the similar. For step-down transformers, the secondary winding has lesser number of turns than the primary. For instance, to step-down voltages from 240 V at the mains to 6 V, there requires to be 40 times more turns in the primary than in the secondary. Within case of step-up transformers, the number of turns in the secondary winding is more than those in the primary winding.
The transformer is one of the simplest of electrical devices, yet transformer designs and materials continue to be improved every day. For an ideal transformer, it is assumed that the whole magnetic flux linked along with the primary winding is also connected to the secondary winding. Therefore, in practice it is impossible to realize this condition. Although a large portion of the flux called mutual or common magnetic flux links with both the coils, a small portion called the leakage flux links only with the primary winding. This leakage flux is responsible to the inductive reactance of a transformer.