This type of transformer adopts high-permedibility cool-rolling si-steel piece as iron core. It is processed with big fill factor and there is no spacing inside the mangnetic path. The HV and LV coil is continuously winded around the core with good concentricity and compact winding. The product is of low con-sumption and slight noise pollution by combining new generation of technolgy good performance and energy saving. It is widely used in power distribution system.