What is a Transformer, and How Does it Work?

Transformers, in the simplest form, are electromagnetic devices that are used to transform power. So, what does that mean? How does it achieve this?

First, let’s look at how they are made. Transformers consist of three main pieces: A core (typically ferromagnetic (iron)), and two individual sets of wire coils. The coils are referred to as the primary and secondary windings.

When applying AC current to the primary winding of the transformer, the coil creates a pulsing magnetic field. The core of the transformer works to direct the path of the magnetic field between the primary and secondary coils to prevent wasted energy. Once the magnetic field reaches the secondary coil, it forces the electrons within it to move, creating an electric current via electromotive force (EMF).

It was discovered that using a solid core was not ideal because a lot of energy was lost in the form of heat due to something called eddy current. To help with this, the cores are now made of laminated sheets of iron to help disperse the heat more evenly and prevent energy loss.

A transformer’s main function is to step-up or step-down the voltage from the primary to the secondary windings. This is done simply by adjusting the ratio of coils on one side to the other. If a transformer has 5 coils on the primary, and 10 on the secondary, it will be a 1:2 step-up transformer, meaning the voltage doubles from the primary to the secondary. Now on the flip side, if it has 10 coils on the primary, and 5 on the secondary, it would be a 2:1 step-down transformer, cutting the voltage in half.

Transformers are fairly simple devices once the base understanding is there. They are available in a variety of types including power, isolation, signal processing, current sensing, and more. Whatever the application, Digi-Key has got it covered. Click here for our wide variety of transformer inventory, including the individual pieces that make up a transformer so you can custom build one to exactly suit your application.

About this author

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Ashley Awalt is a Technical Content Developer that has been with Digi-Key Electronics since 2011. She earned her Associate of Applied Science degree in Electronics Technology & Automated Systems from Northland Community & Technical College through the Digi-Key scholarship program. Her current role is to assist in creating unique technical projects, documenting the process and ultimately participating in the production of video media coverage for the projects. In her spare time, Ashley likes to – oh, wait, is there such a thing as spare time when you’re a mom?

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