#Dry-type Transformer# Oil-immersed transformers and dry-type transformers are common equipment in the power industry. They differ significantly in terms of construction, performance, and application. In the power system, both oil-immersed transformers and dry-type transformers are indispensable devices, but they have distinct differences in various aspects. These differences determine their applicability and advantages in different scenarios.
Cooling medium and insulation method: Completely different design concepts
Oil-immersed transformers use insulating oil as the core medium for both cooling and insulation. Common insulating oils include mineral oil and silicone oil. The iron core and windings are completely immersed in a sealed oil tank, and there are heat dissipation fins or cooling pipes on the outside of the tank. Insulating oil not only has excellent insulation properties but also efficiently transfers the heat generated by the transformer's operation, achieving heat dissipation through natural convection or forced circulation of the oil. However, this design also has certain risks; insulating oil has the problems of leakage and aging, and regular maintenance and monitoring are required.
Dry-type transformers, on the other hand, adopt a completely different design. They use air or gas (such as SF₆) for cooling and rely on solid insulating materials for insulation. Common solid insulating materials include epoxy resin and impregnated paper. The iron core and windings are directly exposed to the air, or are sealed by pouring epoxy resin or other materials. This design avoids the potential risks brought by liquid media, has better moisture-proof and fire-resistant properties, and is relatively easier to maintain.
Performance and Maintenance: Each Has Its Own Advantages
In terms of heat dissipation and overload capacity, oil-immersed transformers excel in large-capacity and high-voltage transmission scenarios, such as outdoor substations, power plants, and 110kV and above high-voltage transmission systems. They also have strong short-term overload capacity. However, this also means that regular checks on oil levels, monitoring of oil quality, and timely replacement of aged insulating oil are required, resulting in relatively high maintenance costs and workload.
The air cooling efficiency of dry-type transformers is relatively low, so their capacity is usually small and they are commonly found in power distribution scenarios of 10kV and below. To improve the cooling effect, dry-type transformers often need to be combined with fans for forced cooling. At the same time, the overload capacity of dry-type transformers is limited, and a precise temperature control system is required to monitor the temperature in real time. When the temperature is too high, an over-temperature alarm will be triggered and the fan will be started, etc. However, the greatest advantage of dry-type transformers is their simple maintenance, usually only requiring regular cleaning of dust. They are particularly suitable for places that are difficult to maintain frequently, such as high-rise buildings and underground power distribution rooms. In addition, the noise generated by dry-type transformers during operation is also relatively low, and it has less impact on the environment.
Application Scenario: Precise Selection Based on Requirements
Due to their different characteristics, oil-immersed transformers and dry-type transformers are suitable for different scenarios. Oil-immersed transformers are more suitable for outdoor open-air environments, can withstand various complex climatic conditions and environmental changes, and require dedicated transformer rooms, oil storage tanks, and complete fire-fighting facilities. Therefore, in outdoor substations, power plants, industrial large motor scenarios, oil-immersed transformers have been widely applied.
Dry-type transformers are mainly used in indoor power distribution scenarios, such as high-rise buildings, commercial centers, data centers, etc. In these densely populated areas, the fire prevention, environmental protection, and low-noise features of dry-type transformers make them the preferred choice. Moreover, in places with extremely high requirements for safety and environment, such as subways, airports, hospitals, and schools, dry-type transformers also play an important role due to their outstanding performance advantages.
