What surrounds the windings in typical "pole-mounted" transformers?

In typical pole-mounted transformers, the windings are surrounded by oil. This oil serves several important functions. First, it acts as an insulating medium, preventing electrical breakdown and allowing safe operation at high voltages. Additionally, the oil helps to dissipate heat generated by the electrical components during operation, which is critical for maintaining efficiency and prolonging the life of the transformer. The oil also facilitates cooling by circulating through the transformer, transferring heat away from the windings and core.

This practice of using oil is essential, as it allows transformers to operate effectively in various environmental conditions, enhancing their durability and reliability in outdoor settings. Other materials like plastic or concrete are not typically used as surrounding mediums for pole-mounted transformers; plastic would not provide adequate insulation or cooling, and concrete is impractical for such applications. Thus, oil is the most suitable choice for these transformers.