A transformer is an electrical device that transfers AC (alternating current) power from one circuit to another using electromagnetic induction. Its main job is to change voltage levels (step up or step down) while keeping the same frequency—so electricity can be transmitted efficiently and used safely by different loads.

In power distribution systems, transformers are essential because the voltage that is best for long-distance transmission is not the same voltage that is safest and most practical for industrial plants, buildings, and equipment.