January 22, 2022

Not every appliance, computer, water heater, television, refrigerator, or light requires the same amount of electricity, or voltage, to run. This is where an electrical transformer comes in.

What Is an Electrical Transformer?

An electrical transformer is a device that takes very high voltages of electricity and reduces it to a suitable voltage for powering your home. When electricity runs through power lines, it can be upward of 300,000-750,000 volts, which is way too high for home appliances and devices. 

Most of the appliances/devices in your home will operate at around 110-250 volts, so a transformer takes the higher voltage electricity and reduces it so that your appliances don’t explode due to excess electrical voltage.

There’s a good reason why lower voltages of electricity aren’t just sent down the wire, to begin with. When electricity runs through the wire, the electrons bounce around and lose energy. The higher voltage of electricity you use, the less energy is wasted. So, we run higher voltage electricity through the lines to conserve energy and then have transformers to lower the voltage going into your home.

How Do Transformers Work?

The next question is, how do transformers actually work? First, you need to understand what they are made of. They have three main pieces: the core and two sets of wire coils. The coils are also called primary and secondary windings.

With that knowledge in mind, the transformers use Faraday’s electromagnetic induction law. A transformer has two circuits that are connected via a common magnetic flux. The transformer generally has a primary and secondary winding. The windings share a laminated magnetic core, and a mutual induction takes place between the circuits that transfer the electricity from one place to another.

In other words, an alternating current (AC) is applied to the primary winding, which creates a magnetic field. The core then keeps the magnetic field between the primary and secondary coils. When the magnetic field gets to the secondary coils, it makes the electrons move, which creates an electric current.

Types of Transformers

There are several kinds of transformers depending on what your electrical needs are. Here is a breakdown.

Based on Design

The two types of transformers based on design are:

  1. Core type transformer
  2. Shell type transformer

Based on Supply

The two types of transformers based on supply are:

  1. Single-phase Transformer
  2. Three-phase transformer

Based on Purpose

The two types of transformers based on purpose are:

  1. Step up transformer
  2. Step down transformer

Based on Use

The three types of transformers based on design are:

  1. Power transformer
  2. Distribution transformer
  3. Instrumental transformer, which breaks down into:
    1. Current transformer
    2. Potential transformer

Based on Cooling

The three types of transformers based on design are:

  1. Self-Cooled Oil-Filled transformers
  2. Water-Cooled Oil-Filled transformers
  3. Air-Cooled (Air Blast) Transformers

Characteristics of a Transformer

There are many different types of transformers, but they all have certain common features. 

  • They are all based on electromagnetic induction laws.
  • The frequency of output and input power is the same.
  • Excluding autotransformers, there are no electrical connections in the coils. All the power transfers through magnetic flux.
  • Unlike other electrical devices, a transformer doesn’t require moving parts, so you don’t get any friction or windage losses. 
  • Generally, most transformers will deliver between 94% and 96% energy when at full load. Some transformers can even deliver up to 98%.
  • Very warm to the touch. You should never touch an electrical wire or a transformer.


Transformers are devices that take high voltage electricity and reduce it to levels that are suitable for our homes. There are many types of transformers, but they all share a lot of similar characteristics. By nature of transferring energy, transformers and electrical wires get pretty warm, so you want to avoid touching them.

At Astley, we are the experts you need. Contact us today for more information.