Transformers are essential in power systems because they enable efficient transmission and distribution of electricity over long distances. By stepping voltage up, they reduce current and I²R losses in lines, making high voltage transmission economical. Later they step voltage down to safe levels for distribution and end use. Without transformers, generation, transmission and utilization would all have to occur at similar voltage, which is impractical. They also allow interconnection of grids with different voltage levels, support voltage regulation and provide isolation for safety and fault control.