R-type transformer is developed on the basis of the advantages of C-type and ring-type transformers. It has the characteristics of small volume, light weight, small leakage magnetic flux, low loss, low temperature rise, simple structure, low noise, commonly used horizontal structure, thin shape, suitable for high-density installation, circular winding, reduced average turn length, low copper loss and low copper consumption. It is widely used in C machine tools, office automation equipment, computers, television cameras and audio equipment.