Abstract: A dry type transformer has an iron core, high voltage windings embedded in cast resin, and low voltage windings resin encapsulated. The low voltage winding is constructed with flexible sheet conductors. Insulating material includes an apparatus to secure the windings in place during a vacuum and pressure resin impregnation process. The result is a coil that exhibits high short circuit protection due to the tightly bond conductors comparable to completely resin encased molded transformers at a substantially reduced cost.

Abstract: A dry type transformer has an iron core, high voltage windings embedded in cast resin, and low voltage windings resin encapsulated. The iron core is manufactured with stacked core steel. After the core is stacked, instead of using banding straps, a heat shrinkable material is wrapped around the core legs and is heated to enable the shrunken material to apply uniform compression over the core legs. This will facilitate coil loading, reduces audible core noise and reduce core losses. In place of shrink wrappable material, a film material with elastic properties could be used.

Abstract: A dry type transformer has an iron core, high voltage windings embedded in cast resin, and low voltage windings resin encapsulated. The low voltage winding is constructed with flexible sheet conductors. Insulating material includes a means to secure the windings in place during a vacuum and pressure resin impregnation process. A unique cylinder or mandril provides a flat surface for one of the low voltage external leads to rest on during the start of the coil winding process. Cooling duct sizes and locations in the windings are varied during winding. The result is a finished coil that maintains an essentially cylindrical shape.