A power transformer is used to transfer electrical power between circuits at different voltage levels while maintaining the same frequency. In power systems it steps up generator voltage to transmission levels, steps down transmission voltage at substations, and interconnects grids with different voltage classes. In industrial plants it feeds large motors and process loads at appropriate voltages. Power transformers also provide galvanic isolation, help manage losses by optimizing voltage levels, and support voltage control through tap changers, making them fundamental components of modern electricity networks.