What are the key differences between dry transformers vs oil transformers?

Dry type transformers use air and solid insulation, while oil filled units use liquid insulation for dielectric strength and cooling. Oil designs usually achieve higher MVA, better thermal performance, and lower noise for outdoor HV service, but need containment, leak management, and oil testing. Dry types reduce spill risk and can be preferred indoors where fire codes and maintenance access matter. Cost depends on rating and installation, with oil units often more economical at higher power and voltage classes.