Variable Auto Transformer will be having round Toroidal Core made from CRGO Lamination duly annealed to reduce the iron Losses and for the good regulation as voltage drop on load is low due to low resistance of conductor & low leakage flux of toroidal core. Toroidal core will provide stepless, beakless, smooth continuous control linearly proportional to angular rotation. Toroidal core is having high efficiency as no load and full load losses are very low and negligible wave from and power factor distortion due to simple transformer action and excellent short time overload capacity. As Toroidal core is having no sharp edge the breakage of insulation and copper wire can be prevented. the toroidal is wound from metal tape wound on to a mandrel under closely controlled tension, then annealed and treated to develop fully the required magnetic characteristic. It has low electrical resistively, no hysteresis loss, a completely linear B-H Curve and an infinitely high saturation points. this permits the easiest direction of magnetization to be utilized.