In a dry type transformer, the operational temperature is primarily determined by which factor?

The operational temperature of a dry type transformer is primarily determined by the insulation type used in its construction. Insulation materials have specific temperature ratings that dictate how much heat they can withstand without degrading. This is crucial because the lifespan and reliability of the transformer heavily depend on the insulation's ability to handle the operational temperatures generated during normal use.

Different insulation materials have different thermal properties. For instance, some insulations can operate effectively up to higher temperatures without losing their insulating qualities, while others may degrade at lower temperatures, leading to potential failure. Therefore, the type of insulation directly influences the maximum temperature that the transformer can safely operate under.

While transformer design, cooling method, and load capacity are also important factors in thermal management, they generally serve to support or enhance the performance associated with the insulation type. Thus, insulation is the critical factor that directly sets the operational temperature limits in a dry type transformer.