Ring core transformers are a major type of electronic transformer, featuring high electrical efficiency, a solid iron core with no air gap, a stacking factor of up to 95% or more, minimal leakage flux, and low electromagnetic radiation. They have a small physical size, light weight, variable with the core, and very low iron loss with low core temperature rise. They are widely used in household appliances and other high-technical-requirement electronic devices, primarily serving as power transformers and isolation transformers. Ring core transformers are already available in a complete series overseas, widely applied in computers, medical equipment, telecommunications, instruments, and lighting.