Working Principle of a Simple Transformer

What is a Transformer?

A transformer is a stationary electrical device or machine. A transformer can not convert electrical energy into another energy, it only transforms electrical energy from one circuit to another circuit at one voltage level to another voltage level. That's why it's named Transformer. Obviously, Transformer work in AC cannot work in DC. The transformer does not change frequency and power. The transformer has no rotating part that's why it is called a stationary device or machine.

Construction of a Simple Transformer:

The transformer has two stationary electric circuits or winding or coils that are coupled magnetically. There is no electrical contact between them. The primary and secondary coil wound on a ferromagnetic material which is called a Core. The core transfer the changing magnetic flux from the primary winding or coil to the secondary winding or coil. Each winding or coil of the Transformer has no of turns as per the requirement voltage level.

Working Principle of Transformer:

The transformer works in the principle of mutual induction. The AC supply fed to one of the two coils which are called the primary winding and the other winding which is connected to the load is called secondary winding. So when the alternating current flows in the primary coils, a changing magnetic flux is generated which is linked with both the primary and secondary coil by the core. According to Faraday's laws of electromagnetic induction, an EMF is induced in the secondary winding. This induced EMF drives a current if a load is connected to the secondary winding. The magnitude of the output voltage can be controlled by the ratio of the no. of the primary coil and the secondary coil. Self-Inductance also has seen in the primary winding in a Transformer which limits the flow of current in the primary winding.

How Transformers Step Up and Step Down the Voltage?

The transformer which can step up the voltage is called Step Up Transformer. It has more turns in the secondary coil compared to the primary coil. When the AC current flows through the primary coil, the changing magnetic field induces a higher voltage in the secondary coil. This allows electricity to be supplied at a higher voltage than the input voltage.

On the other hand, the transformer which can step down the voltage is called Step Down Transformer. It has fewer turns in the secondary coil compared to the primary coil. When the AC current flows through the primary coil, the changing magnetic field induces a lower voltage in the secondary coil. This allows electricity to be supplied at a lower voltage than the input voltage.

So the basic principle behind this voltage change is the relationship between the number of turns in the coils and the induced voltage. More turns in the secondary coil result in a higher voltage, while fewer turns result in a lower voltage.

Why Transformer cannot work in DC?

If a DC supply is given to the transformer the produced flux remains constant it does not change so EMF will be not induced. As self-inductance does not appear in the primary winding a huge amount of current will flow through the primary coil(As the coils of the transformer have low resistance), so the winding gets damaged. For this reason, the transformer cannot work in DC.

How to use a DC supply with a Transformer?

If you want to step down or step down a DC supply using a transformer then you need to convert the DC supply into AC. This can be achieved using an electronic device called an inverter or by using a DC-AC converter. These devices convert the DC voltage into an AC voltage with the desired frequency. Once you have converted the DC supply into AC, you can use the transformer to step up or step down the voltage as needed. Connect the primary winding of the transformer to the output of the inverter or DC-AC converter. The secondary winding will then provide the stepped-up or stepped-down voltage. Now you need to convert the transformed AC voltage back to DC. A rectifier circuit, such as a bridge rectifier, converts the AC voltage into DC by eliminating the negative cycles of the AC waveform. This can be useful if you require a DC output after the voltage transformation.

Classification of Transformer:

1. Shell Type
2. Core Type
3. Berry Type

Based on Output Voltage:

1. Step-up Transformer
2. Step-down Transformer

Based on Application:

1. Power Transformer
2. Distribution Transformer

Based on the number of Phases:

1. Single Phase Transformer
2. Three Phase Transformer