Ring-core transformers are a major type of electronic transformers, featuring high electrical efficiency, a solid iron core without air gaps, and a stacking factor of up to 95% or more. They have minimal leakage flux and electromagnetic radiation, with a small physical size and light weight. Their design varies with the core, resulting in very low iron losses and low core temperature rise. They are widely used in household appliances and other high-tech electronic devices with stringent technical requirements, primarily serving as power transformers and isolation transformers. Ring-core transformers have a complete range available internationally and are extensively used in computers, medical equipment, telecommunications, instruments, and lighting.