In power transmission, transformers enable efficient long distance transfer of energy by stepping voltages up and down. At generating stations, step up transformers increase voltage to transmission levels, reducing current and line losses. Along transmission routes and at receiving ends, step down transformers reduce voltage to levels suitable for sub transmission and distribution networks. They also facilitate interconnection of systems with different voltage tiers, support voltage regulation via tap changers and help control short circuit levels. Without transformers, high voltage transmission and modern interconnected grids would not be practical.