Which type of transformer is generally used for outdoor applications due to its robustness?

The oil-filled transformer is typically used for outdoor applications due to its robust construction and the inherent advantages of the insulating oil used within it. This type of transformer is designed to withstand extreme environmental conditions, including harsh weather, while ensuring reliable operation. The oil not only serves as an insulator but also dissipates heat effectively, helping to maintain optimal operating temperatures even under heavy loads.

Furthermore, oil-filled transformers are commonly sealed and can be placed in outdoor enclosures or even submerged in water, allowing for flexibility in their deployment. Their design typically incorporates features that protect them from moisture and other environmental factors that could affect performance.

In contrast, other types of transformers, such as dry type transformers, are more suited for indoor use where environmental exposure is controlled. Planar and toroidal transformers, while efficient for specific applications, do not have the same level of ruggedness or suitability for outdoor deployment. Thus, when considering robustness and outdoor application, the oil-filled transformer stands out as the ideal choice.