Transformer and its working principle

In this post we will discuss Definition of Transformer and its working principle A transformer is a static device, it means it has no rotating parts like the other electrical machines such as synchronous machines and induction machines. A transformer transfers electrical energy from one circuit to the other without any direct contact between the two circuits. The two circuits are interlinked with a common magnetic circuit (magnetic core). A transformer transfers the energy from one circuit to another without any change in the frequency.

Transformers basically works on the principle of Faraday’s Law of Electromagnetic Induction, which states that “when a conductor is placed in the changing(varying) magnetic field then emf will induced which is known as induced emf and if the circuit is closed then current will flow in it which is known as induced current”

In the above circuit, the first winding is known as primary winding and the second one is known as secondary winding. An alternating voltage source is connected with the primary winding which will produce a varying magnetic field when a current i flows through it. Now when we bring the secondary winding near to the primary, the changing magnetic field will link to it and according to the Faraday’s Laws of electromagnetic induction an emf E will induced in the secondary side as shown in the fig. above.

As we can see that the magnetic field lines generated due to the primary coil are not able to link completely with the secondary coil, so the losses are more. Thus we need a magnetic medium to link both the coils in a effective way. A magnetic core is placed as shown in fig. below. This magnetic core is made up of thin sheets called laminations of high grade steel silicon steel . the laminations reduce eddy current losses and silicon steel reduces hysteresis loss.

Let T₁ and T₂ be the number of turns in the coils 1 and 2 respectively. when a source of alternating voltage V is applied to coil 1, an alternating current I₀ flows in it. This alternating current produces an alternating flux ɸ_M  in the magnetic circuit. The mean path of this flux is shown in fig. by dotted line. The alternating flux links the turns T₁ of coil 1 and induces in them an alternating voltage E₁ by self-induction. The flux linking with the coil 2 will induces an alternating voltage E₂ by mutual induction.

The coil which is connected with the supply source is known as primary coil or winding and the side which is connected with the load is known as the secondary coil or winding.

Types of transformers

Step up transformer- a transformer in which the output(secondary) voltage is greater than its input (primary) voltage is called a step-up transformer.

Step down transformer- – a transformer in which the output (secondary) voltage is less than its input (primary) voltage is called a step-down transformer.

 A same transformer can be used as a step up or step-down transformer depending on the way it is connected to the circuit. If the primary winding has less no. of turns (low voltage side) as compared with the secondary then it will be a step-up transformer.

If the no. of turns in the primary coil are more (high voltage) as compared to the secondary side then it will be a step-down transformer.

It means the number of turns of the coil will decide the voltage level of the winding in both sides.

A transformer which receives one voltage and delivers the same voltage is known as the one to one transformers  T₁ = T₂ and E₁ = E₂. Such a transformer is used to isolate the two circuit.

As I have made a full playlist on Transformer on my youtube channel, so you can visit. Here I am providing the video for Transformer and its working principle.

Watch the video here for better understanding.

There are some other categories of transformers which are classified according to their uses such a power transformer, distribution transformer, auto transformer etc. we will discuss them in the further sessions.

We will discuss about an ideal transformer and emf equations of transformers in the upcoming post. kindly do support and give your valuable feedback. you can also visit our you tube channel for easy explanation of this video and chapter.