How Does a Transformer Work?

What is a transformer?

Let’s start with the basics. A transformer is a device that adjusts the voltage of electricity that pumps through your appliances in your home. Why do we need to do adjust the voltage for appliances to work, you ask? Well, the power that is transported to the utility lines from the power plants produces high voltage as it travels to your home. These power lines of high voltage can produce anywhere from 155,000 to 765,000 volts of electricity! Household appliances can only handle so much voltage to be able to function; therefore, it’s essential that a transformer is placed on the utility poles to lower the voltage of electricity for certain appliances to work properly. Before the voltage is lowered by the transformer on your outside utility pole, it needs to be lowered by transformers in substations from 155,000 volts down to 7,200 volts. Then, the transformer from your utility line lowers the voltage once again between 220 and 240 volts so that your household appliances can function smoothly.


Some businesses can handle the amount of voltage that the substations create to power big machinery; however, when the voltage is too high for some machinery, it becomes necessary to install a transformer to lower the voltage for the specified equipment. Take a look at the video below of a recent transformer installation by KB Electric LLC for a commercial metal press machine:



How a Transformer Works

So now that you know a little about transformers and their importance for distributing electricity to your home, let’s take  a look at how they operate! Transformers do not generate electricity. Transformers simply increase or decrease electrical voltage by transferring one AC circuit to another using electromagnetic induction with two coils (single phase transformer). The first coil is called the primary winding coil, which is on the primary side that has the original electrical voltage that is needed to be adjusted. The second coil is called the secondary winding coil, which is on the secondary side that takes the transformed voltage (either increased or decreased from the original) and transfers it into the appliance, machinery, or other equipment.

Alternating currents of voltage go through the primary coil, and produces alternating magnetism in the core of the transformer. The magnetic field then passes through the secondary coil, producing alternating voltage in the secondary coil. The amount of voltage and the ability to increase or decrease volts for an appliance has to do with the ratio between the number of turns in the wire of each coil. If the secondary winding has more turns in its coil than the primary winding, the voltage will increase, meaning more voltage than what is originally coming into your business from the utility line. If the secondary winding has less turns in its coil than the primary winding, the voltage produced will be lower than what is coming from your utility line.

If the last part didn’t confuse you enough, that’s just the beginning!