How do oil type transformers differ from dry-type transformers?

Oil type transformers use liquid insulation and cooling, allowing higher voltage ratings, compact design, and better heat dissipation. Dry-type transformers use solid insulation and air cooling, reducing fire and spill risks but limiting power density. Oil transformers dominate transmission and outdoor substations, while dry-type units are preferred indoors or where oil containment is restricted. The choice depends on voltage level, fire safety, environment, and cost.