Differences and advantages and disadvantages between dry-type transformers and oil immersed transformers

The difference between dry-type transformers and Oil Immersed Transformers

Of course, they are all Power Transformers with iron cores for magnetic circuits and windings for circuits. The biggest difference is between "oil type" and "dry type". That is to say, the cooling medium of the two is different. The former uses transformer oil (of course, there are other oils such as β oil) as the cooling and insulation medium, while the latter uses air or other gases such as SF6 as the cooling medium. Oil Transformer refers to placing the body composed of iron core and winding in an oil tank filled with transformer oil. Dry transformation often involves encapsulating the iron core and winding with epoxy resin casting. There is also a commonly used non encapsulated method, where the winding is coated with special insulation paper and then dipped in specialized insulation paint to prevent moisture from affecting the winding or iron core.

In terms of production and usage, the current voltage level of dry transformers is only up to 35kV, and the capacity is relatively small compared to oil transformers, about 2500kVA. Additionally, the manufacturing process of dry transformers is more complex and costly compared to oil transformers of the same voltage level and capacity. So currently, in terms of usage, there is still an increase in oil. However, due to its environmental friendliness, flame retardancy, impact resistance, and other advantages, it is often used in high demand indoor power distribution plants such as hotels, office buildings, high-rise buildings, and so on. If you are just a transformer user, understanding these should be enough.

"Each has its own advantages and disadvantages. Oil transformers have low cost and easy maintenance, but they are flammable and explosive. Due to its good fire resistance, dry-type transformers can be installed in the load center area to reduce voltage and energy losses. But dry transformation has high prices, large volume, poor moisture and dust resistance, and high noise.  

Oil transformation gradually exits, using dry transformation. Dry transformation can be disassembled for transportation, cleaned, easy to maintain, and does not require a machine base for installation. There is no oil leakage pool The advantages are relatively easy to distinguish from the appearance;  

The biggest difference between oil immersed transformers and dry-type transformers is the presence of "oil". As oil is a liquid with fluidity, oil immersed transformers must have an outer shell, which contains transformer oil inside. The transformer coils are immersed in the oil and cannot be seen from the outside; Dry type transformers do not require oil, so there is no need for a casing and the coils of the transformer can be directly seen; Another characteristic is that oil immersed transformers have oil pillows on top, which store transformer oil inside. However, modern oil immersed transformers also have transformers produced without oil pillows;  

For the convenience of heat dissipation, that is, for the flow and heat dissipation of internal insulation oil, oil immersed transformers are designed with radiators on the outside, just like heat sinks. However, dry-type transformers do not have this radiator, and heat dissipation relies on the fan under the transformer coil, which is somewhat similar to the indoor unit of a household air conditioner;  

Oil immersed transformers are generally installed in separate transformer rooms or outdoors due to fire prevention requirements, while dry-type transformers are definitely installed indoors. Generally, they are installed in low-voltage distribution rooms and installed side by side with low-voltage distribution cabinets.