A transformer is basically an electric device intended to transfer electric power from one electric circuit to another, without changing its frequency. Most widely used are the transformers for transmitting electric energy to houses from power stations, while others may be used in electronic appliances for the purpose of regulating voltage. Voltage needs to be regulated because the electrical appliances’ requirement is different from that of the electric current supplied. Hence regulators are fitted along with appliances to control the supply of current to avoid any short circuiting.
WORKING OF A TRANSFORMER
A transformer has a primary coil and secondary coil. The coils are wound over the opposite sides of a square shaped metallic sheet or construction of many thin laminated steel sheets, known as the transformer core, which provides a controlled path for magnetic flux generated through current transmission.
When an input voltage is applied to the primary winding, alternating current starts to flow in it. As the current flows, a changing magnetic field is set up in the transformer core. As this magnetic field cuts across the secondary winding, alternating voltage is produced in the secondary winding. The ratio between output voltage and input voltage is the same as the ratio of the number of turns between the two windings. If the output voltage is stepped up due to larger number of turns in secondary coil, it is considered to be a “step- up transformer”. If the secondary winding has fewer turns that primary winding, the output voltage is lower. This is a “step down transformer”.
The principle behind this working is Faraday’s law of electromagnetic induction, which says that whenever we apply alternating current to an electric coil, there will be an alternating flux surrounding that coil. This induces an electromagnetic flux in the second coil, whereby current flows in it.
TYPES OF TRANSFORMERS
Various types of transformers are used in electric power distribution, transmission and utilization. Some of them are-
- Auto transformer –
Transformers in which primary and secondary winding have a common circuit part. This leads to smaller size and increased voltage regulation.
- Distribution transformer, power transformer –
Distribution transformers distribute electric energy through transmission lines for consumption in houses. Power transformers transmit electric energy from generator to the distribution centers.
- Resonant transformers-
Transformers that use resonance to generate a higher secondary voltage.
- Audio transformer-
Transformers used in audio equipment.