Drying and oil impregnation of power transformer insulation

The processing procedure described above has already resulted in several important benefits of interest to both the manufacturers and the users of power transformers: 1. Insulation structures which formerly would have been impossible or impractical to properly dry and impregnate can now be easily processed in a relatively short time. This allows the. transformer designed to use design practices on high rating units which would not have been permissible formerly. It also extends upward the maximum ratings which can be built. 2. The electrical, magnetic and mechanical parts of transformers of all ratings can be designed and built to much closer tolerances because of the consistently thorough drying and dimensional stabilization of the insulation obtained by this process. For example, the magnetic core can now be designed to have a closer fit with the coils, thus reducing the amount of wasted space without applying damaging physical stresses to co re material during assembly. 3. Because of the more dependable electrical properties of the insulation resulting from the more rigorous drying, the required insulation clearances can be more accurately calculated with more assurance that the transformer will stand up on test and in service. 4. The transformer will never be any drier in service than at the time the core-coil assembly is put together and assembled onto the tank, so that the coils will not loosen up in service. Movement of the coil conductors and leads under short-circuit conditions should be effectively prevented for the entire life of the transformer. 5. The time required to manufacture a power transformer has been reduced by from a day to a week or more because of the shortened processing time. This is of assistance both to the manufacturer and the customer, making it easier to meet short delivery dates.