What are the different types of oil transformers?

Oil transformers are classified by application and cooling method. Common types include distribution transformers, power transformers, current and voltage transformers, and special purpose units. Cooling classes include ONAN, ONAF, OFAF, and OFWF. Design variants include conservator type, sealed type, and hermetically sealed transformers. Each type is optimized for voltage level, load profile, installation environment, and maintenance strategy.