1.) Cast Resin Dry Type Transformer (CRT): This type of transformer is employed in locations that are prone to high levels of moisture. It is as a result of its epoxy resin-encapsulated main and secondary windings. Its encapsulation aids in guarding against moisture intrusion that could harm the winding material. Its cast resin encapsulation provides total protection, allowing the transformer to operate without interruption at a location that is very susceptible to moisture. This transformer is not hygroscopic as a result. With insulation class F, this type of transformer is offered in ratings ranging from 100 KVA to 5000 KVA (90oC Temp. Rise).
2.) A vacuum pressure impregnated transformer (VPI) is one that uses the least amount of combustible material possible to insulate its windings. This transformer's windings are constructed from foil or strip in a continuous layer. The winding, however, is formed of discs that are connected in series or parallel depending on the voltage level's power rating for higher voltages. Class H polyester resin is used to create void-free impregnation, which serves as the winding's insulation. In a vacuum-sealed box, the primary and secondary windings with the core are safely lashed. High Moisture Ingress Protection ensures that moisture never affects it.