Transformers

Transformers are the devices that work on the principle of mutual induction and are responsible for the transformation of altering voltage from higher to lower or lower to higher values.The idea of a transformer was first discussed by Michael Faraday in 1831. The general use of transformers is to maintain a balance between the electricity of high voltage and low voltages.

TRANSFORMER- 

A transformer works on mutual induction and is responsible for transforming alternating voltage from one value to another. There are two types of transformers – The step-up transformer, which decreases the output current, and the step-down transformer, which increases the output current.

To put it simply, the transformer performs the function of controlling voltage and hence helps in the easy transmission of alternating current. Michael Faraday primarily pictured the transformer in 1831. 

PARTS OF TRANSFORMERS 

Core- this is the support to the transformer and is responsible for or providing a low reluctance path to the flow of magnetic flux. On this core, winding off of wire is done.

• The core is composed of soft iron for the sake of reduction of the losses
• The diameter of the core is proportional to the losses

The primary and the secondary coil- The coils are wrapped around the transformer’s core. These coils are made up of copper to minimise the losses since copper is highly conductive. There are two types of coils-

• Primary coil: Denoted by NP (number of turns essentials of the primary coil). It is here that the input is given. 
• Secondary coil: Denoted by NS (number of turns of the secondary coil). It is here that the output is received.  

It is important to note that the presence of insulation is crucial to separate the primary coil from the secondary coil; insulating oils, insulating tapes, insulating papers, or wood-based lamination is used for the same. 

WORKING OF TRANSFORMERS 

Transformer works on the principle of Faraday’s law of electromagnetic induction and mutual induction. The two coils that are the primary coil and the secondary coil, are separated by the laminating material and are found on the transformer’s core. 

When an alternating current, AC, is passed through the primary coil, the input coil creates a change in magnetic flux. As stated by Faraday’s law of electromagnetic induction, the change in magnetic flux induces an EMF, and an Is produced in the secondary output coil through the means of mutual induction. 

EP = – NP dΦ/dt

ES = -NS dΦ/dt

AC voltage obtained across secondary  VS = ES  NS

AC voltage obtained across primary  VP = EP NP

VS = (NS/ NP) VP

IS = (NP/NS) IP

Where VP  is the Primary Voltage

 VS  is the Secondary Voltage

IS  current through the secondary coil

IP  current through the primary coil

NP  is the Number of Primary coil

NS  is the Number of Secondary coil

EP  emf induced across the primary coil

EP  emf induced across the secondary coil

Φ  is the Flux Linkage

The above relations are based upon the following three assumptions-

• Primary current and resistance are small
• Tiny flux links both the primary and secondary coil
• The secondary current is small

In actual transformers, small energy losses occur due to the following aspects-

• Flux Leakage- some amount of flux is always leaked, as there is no complete transfer of flux from primary to secondary
• Resistance of the coils- because of resistance and heat dissipation, some energy is lost
• Eddy Currents- the alternating magnetic flux leads to the production of Eddy Currents in the iron core and causes heating. This loss can be minimised if laminated iron core is used
• Hysteresis- because of repeated reversion of alternating current and magnetic field, the core gets magnetised, leading to the expenditure of energy in the core in the form of heat. 

Transformers Types

Transformers can be divided into different types according to their functionality. 

Based on Voltage Levels

Depending upon voltage they are classified into two types:

● Step-up Transformer

● Step down Transformer

Based on the Medium of Core Used

In transformers, we will find different types of cores used.

● Air core Transformer

● Iron core Transformer

Based on Install Location

• Power Transformers

• Distribution Transformer

• Measurement Transformers

• Protection Transformers

Applications Of Transformer

1. Used for long distance electric transmission.
2. Used in electric devices like radio and TV receivers.
3. For voltage regulation transformers are used.

Conclusion

Most simply, the transformer can be described as a thing that steps up or steps down voltage. In a step-up transformer, the output voltage is increased, and the output voltage is decreased in a step-down transformer. The step-up transformer will reduce the output current, and the step-down transformer will increase the output current for keeping the input and the output power of the system equal.

The transformer is a voltage control device used widely in the distribution and transmission of alternating current power. Michael Faraday first discussed the idea of a transformer in 1831.