What are the main differences between dry type and oil type transformers?

Oil type transformers use liquid insulation for higher dielectric strength and effective cooling, making them common for outdoor HV and high MVA ratings. They require oil testing, leak management, containment, and fire risk controls. Dry type transformers use air and solid insulation, reducing spill risk and often preferred indoors where environmental containment is difficult. Dry types can be larger at high ratings and may have different noise and thermal behavior. Selection depends on location, rating, fire and environmental codes, maintenance capability, and life cycle cost.