Transformers require:

Transformers are designed to be robust and reliable, which contributes to their relatively low maintenance requirements compared to other types of electric machinery. The design and materials used in transformer construction, such as high-quality insulation and sturdy components, help minimize wear and the likelihood of failure.

In many cases, transformers can operate effectively for many years without needing significant maintenance, provided they are installed and operated under suitable conditions. Regular maintenance schedules are usually minimal, often involving periodic inspections rather than ongoing intensive maintenance. This characteristic helps to reduce operational costs and allows for more efficient management of resources.

Regular inspections are advisable but do not need to be as frequent as monthly or even every three years for typical operation, as suggested by the other choices. This further emphasizes how transformers, when well-designed and properly utilized, require less frequent and intensive maintenance protocols, making them distinct from many other pieces of electric machinery that may require more regular upkeep.