A power transformer is an electrical device used to transfer electrical energy between two or more circuits through electromagnetic induction. It adjusts voltage levels to ensure efficient power distribution in electrical grids, allowing electricity to travel long distances without significant loss. Power transformers are essential in substations, where they step up voltage for transmission or step down voltage for distribution to homes and businesses. They are designed to handle high voltage and current levels, ensuring safety and reliability in the electricity supply system. Proper maintenance of power transformers is crucial for the stability of the power grid.