Transformer has made long-distance transmission of electric power a practical reality, as AC voltage can be “stepped up” and current “stepped down” for reduced wire resistance power losses along power lines connecting generating stations with loads. At either end (both the generator and at the loads), voltage levels are reduced by transformers for safer operation and less expensive equipment.

step-up transformer - is a type of transformer that increases voltage from primary to secondary (more secondary winding turns than primary winding turns). They convert voltages to higher volumes while reducing amperage and effects of resistance. This makes Step-Up Transformers ideal in long-distance power transmission use; by stepping up voltage and reducing amperage little energy is lost to resistance

step-down transformer - is a type of transformer designed to do just the opposite (more primary winding turns than secondary winding turns). This transformer converts high-voltage, low-current power into low-voltage, high-current power