How does a Transformer Work

What is a Transformer
A transformer is an electrical device, used to increase or decrease the AC voltage. Some transformers, called the isolation transformers, do not change the magnitude of voltage and their output is the same as that of the input. These transformers provide isolation and ensure that the voltage does not fluctuate. A transformer transfers electricity from one part of the circuit to another. Transformers have a primary winding and a secondary winding of wires around a core. The core of transformers is made of materials like air, soft-iron and steel. The transformer transfers electricity from primary winding to the secondary winding. There are two types of transformers viz. step-up and step-down. The step-up transformer gives a higher voltage at secondary winding as compared to the primary winding. In case of the step-down transformer, the voltage at the secondary winding is less than that at the primary winding. Let us now understand exactly how does a transformer work.

How does a Transformer Work
The working of a transformer is based on the relationship between magnetism and electricity. In a step-up transformer, the secondary winding has more number of turns (the number of the times the wire makes a complete turn on the core) as compared to the primary winding. On the other hand, the secondary side of a step-down transformer has less number of turns as compared to that of the primary winding. The turns ratio of the transformer refers to the ratio of the number of windings on the primary side, to the number of windings on the secondary. The turns ratio decides whether the transformer increases (step-up) or decreases (step-down) the input voltage.

The primary coil and the secondary coil are inductively coupled to each other. An alternating voltage of the particular frequency is applied to the primary coil and an alternating voltage of same frequency is induced in the secondary coil. Usually, an iron core is used because iron core provides high permeability to the magnetic flux. The magnetic flux is the amount of magnetic field passing through a given area. Permeability is a property of iron that allows the magnetic flux to flow through the core. Higher the permeability, less is the resistance offered to the magnetic flux that is flowing through the core. In case of iron core, most of the magnetic flux is restricted only to the core. Due to this restricted magnetic flux, there is a higher degree of coupling between the primary and the secondary coil.

All the transformers do not have only one coil at the output. A single primary winding and a single voltage source can be used to obtain voltages of different values at the output. This is done by using separate windings for the secondary, according to the required output voltage. This ability of the transformers, makes it very easy to provide the required voltage demand by utilizing a single source.

In modern day power systems, the transformers are adjunct devices. The transformers are also used for electricity distribution over long distances. The electricity transmitted from the power generation stations is of very high voltage so that it can travel long distances. Transformers are used to step-down the voltage and supply this stepped down voltage to the sub-stations. The sub-stations again step down the voltage to 7200V and sent it to a transformer, fitted in your neighborhood. These transformers in turn step-down the voltage to the required 220-240V and 110-120V, which is then sent over a three wire system to the electric meter in your house. The two wire system supplies the required electricity and the third wire is grounded. Transformers are essential devices used in the power systems. Thus, we have seen how does a transformer work.