What is the oil type used in distribution transformers?

The oil type used in distribution transformers is typically mineral oil. Mineral oil serves as an insulating and cooling medium, effectively dissipating heat generated during operation. It has excellent dielectric properties, which are crucial for maintaining electrical insulation and preventing breakdown. Additionally, some distribution transformers may use synthetic or biodegradable oils as alternatives, but mineral oil remains the most common choice due to its availability and cost-effectiveness.