When many people think of transformers, they see those high voltage units feeding power to homes and business or large enclosed areas with strange buzzing noises. However, there are many electrical transformers working hard behind the scenes inside panels and electrical equipment. How do these things work? Let’s take a closer look and see.
Magnetic Energy and Inductance
When you pass electricity through a wire, it produces an electromagnetic field. If you coil the wire, the magnetic field intensifies. On the other hand, when a magnetic field creates an electric current, this is inductance.
Transformer Theory
Imagine two coils of wire and both coils share an iron core. The primary coil receives AC electricity from a power source, and this creates magnetic energy which causes current to flow through the secondary coil of wire. This is important because electrical transformers have the power to change voltage.
Suppose the primary coil receives 120 volts AC and the wire wraps around the coil 100 times (100 ampere-turns). The secondary coil has 50 ampere-turns of wire. Current enters the primary side of the transformer at 120 volts and leaves the secondary side at 60 volts. Voltage change is in direct proportion to the ampere-turn differences between the coils.
Step Up and Step Down
When the primary coil has more wire than the secondary coil, you have a step-down transformer. Reverse the situation, and you get a step-up transformer. Power going to your house enters a transformer at about 14,000 volts and steps down to 120 volts per conductor. This is an example of a step-down transformer.
Step-up electrical transformers raise the voltage. Fluorescent lighting needs high voltages to ignite the gas inside of fluorescent tubes. They use step-up electrical transformers called ballasts. Many products today use transformers to change voltages, including microwave ovens and computers.
