Oil vs Dry: Oil-Immersed vs Dry-Type Transformers – Which One Should Power Your Electricity Needs?

• Oil-Immersed Transformer: An oil-immersed transformer usually has an outer shell filled with transformer oil, with the coils submerged in the oil, making them invisible from the outside.

• Dry-Type Transformer: A dry-type transformer does not use oil; the core and coils are directly visible and typically do not require an external casing.

• Oil-Immersed Transformer: Due to the use of flammable transformer oil, there is a certain fire risk involved. Regular maintenance and inspections are necessary to ensure safety.

• Dry-Type Transformer: Dry-type transformers use air or other gases as insulation mediums, reducing the likelihood of fires and enhancing safety. They are well-suited for densely populated areas such as inside integrated buildings.

• Oil-Immersed Transformer: Suitable for high-capacity requirements, commonly used in independent substations and outdoor temporary power situations. For instance, China's ongoing 1000KV UHV test line uses oil-immersed transformers.

• Dry-Type Transformer: Ideal for medium and small capacity needs, often found in basements, within floors, or on rooftops where space is limited. Box-type substations predominantly use dry-type transformers.

• Oil-Immersed Transformer: Relatively lower initial cost with simple maintenance but may involve higher long-term maintenance expenses.

• Dry-Type Transformer: Although the initial purchase cost is higher, their maintenance-free and long-life characteristics result in lower overall operating costs.

• Oil-Immersed Transformer: Cooled through transformer oil, providing good heat dissipation but requiring regular oil quality checks.

• Dry-Type Transformer: Utilizes natural air cooling or forced air cooling for heat dissipation, offering simple maintenance and being environmentally friendly.

• Oil-Immersed Transformer: Suitable for both dry and humid environments, though special attention must be paid to moisture protection in high humidity conditions.

• Dry-Type Transformer: Excellent moisture resistance, capable of operating under 100% humidity, and can be put back into operation without pre-drying after being out of service.