In an electrical power system, the transformer’s main purpose is to change voltage levels efficiently while transferring power between circuits. At generation, transformers step up voltage for transmission to reduce current and line losses. Along the network they step down voltage at substations for regional and local distribution. Near consumers they further reduce voltage to safe, usable levels for homes and industry. They also provide isolation between systems, support reactive power control with tap changers, and enable flexible interconnection of grids with different voltage classes.