Ring-type transformers are a major type of electronic transformers, featuring high electrical efficiency, a solid core with no air gap, a stacking factor of up to 95% or more, minimal leakage flux, low electromagnetic radiation, compact size, light weight, variable with the core, very low iron loss, and 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-type transformers have a complete series available internationally and are extensively used in computers, medical equipment, telecommunications, instruments, and lighting.