What is a Transformer?
A transformer is an electrical device that changes (transforms) the voltage of an alternating current (AC) supply. Transformers are everywhere in modern life — from the charger for your phone to the massive metal boxes on electricity pylons that distribute power across entire cities.
An electrical device that uses electromagnetic induction to increase or decrease the voltage of an alternating current (AC) supply.
Transformers are essential because electricity generated at power stations needs to be transmitted over long distances, and then stepped down to safe voltages before it enters your home. Without transformers, the entire modern electricity grid would simply not function.
Think of voltage like water pressure in a pipe. A transformer is like a pump system that can either boost the pressure (step up) or reduce it (step down) depending on what you need at different points in the system.
Structure of a Transformer
A transformer has three key components:
- Primary coil — a coil of insulated wire connected to the input (source) voltage
- Secondary coil — a coil of insulated wire connected to the output (load)
- Iron core — a soft iron core that links both coils magnetically
The two coils are electrically isolated from each other — they are NOT directly connected by wires. Energy is transferred between them entirely through the magnetic field in the iron core.
The input coil of a transformer, connected to the AC supply voltage.
The output coil of a transformer, from which the transformed voltage is taken.
The soft iron centre of a transformer that channels the changing magnetic flux from the primary coil to the secondary coil.
The iron core is made of soft iron (not steel) because soft iron magnetises and demagnetises easily and quickly, allowing it to respond to the rapidly changing alternating current. The core is also usually laminated (made of thin layers insulated from each other) to reduce energy losses from eddy currents.
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