What's the difference between dry-type and oil-immersed transformers? How should I choose?

Dry-type transformers are required in complex buildings (basements, floors, rooftops, etc.) and crowded areas. Oil-immersed transformers are used in independent substations. Dry-type transformers are generally used for transformers within box-type substations. Oil-immersed transformers are generally used for temporary outdoor power supply. During construction, the choice between dry-type and oil-immersed transformers should be based on the available space. Oil-immersed transformers can be used for larger spaces, while dry-type transformers are preferred for more crowded areas.

Oil-immersed transformers are more suitable for areas with humid and hot climates. If dry-type transformers are used, they must be equipped with forced air cooling.

1. Appearance: Dry-type transformers have different packaging styles. The core and coils are visible in dry-type transformers, while only the outer casing is visible in oil-immersed transformers.

2. Different lead types: Dry-type transformers generally use silicone rubber bushings, while oil-immersed transformers mostly use porcelain bushings. 3. Differences in capacity and voltage: Dry-type transformers are generally used for power distribution, with capacities generally below 1600 kVA and voltages below 10 kV, though some are available up to 35 kV. Oil-type transformers, on the other hand, can cover a wide range of capacities and voltages, from small to large. China's currently under construction 1000 kV UHV test line exclusively utilizes oil-type transformers.

4. Differences in insulation and heat dissipation: Dry-type transformers are generally insulated with resin and cooled by natural air, with larger capacity transformers using fans. Oil-type transformers, on the other hand, rely on insulating oil for insulation, which circulates within the transformer to dissipate heat generated by the coils to the transformer's heat sink.

5. Applicable Locations: Dry-type transformers are mostly used in locations requiring fire and explosion protection, and are generally suitable for large and high-rise buildings. Oil-type transformers, however, are often used outdoors, where there is space for an emergency oil reservoir, as oil spills or leaks could cause fires in the event of an accident. Dry-type transformers are more suitable for indoor, environmentally friendly, and highly secure applications, while oil-immersed transformers are more suitable for outdoor, large-capacity, and long-term operation. When choosing the right transformer, consider power requirements, installation environment, budget, and ongoing maintenance capabilities to make the most appropriate decision.