Oil-immersed transformers are used in independent substations. Dry-type transformers are generally used for transformers within box-type transformers. Oil-type transformers are generally used for temporary outdoor power supply. During construction, the choice between dry-type and oil-type transformers is determined by the available space. Oil-type transformers can be used for larger spaces, while dry-type transformers are preferred for more confined spaces. Oil-type 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. Different packaging: Dry-type transformers allow the core and coils to be directly visible, while oil-type transformers only allow the outer casing to be visible.
2. Different lead types: Dry-type transformers generally use silicone rubber bushings, while oil-type transformers generally use porcelain bushings. 3. Different Capacities and Voltages: 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. The 1000 kV UHV test line currently under construction in my country exclusively uses oil-type transformers.
4. Different 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 may spray or leak in the event of an accident, potentially causing a fire. 6. Different load-bearing capacities: Dry-type transformers generally operate at rated capacity, while oil-type transformers have better overload capacity.
7. Different costs: For transformers of the same capacity, dry-type transformers are significantly more expensive than oil-type transformers. Dry-type transformer model numbers generally begin with SC, representing epoxy resin encapsulated type, SCR non-epoxy resin encapsulated solid insulation type, and SG open type. Dry-type transformers mostly use silicone rubber bushings, while oil-type transformers mostly use porcelain bushings.