DC voltage/current heating/gelling/curing of resin encapsulated distribution transformer coils

An internal heating method for drying, gelling and final curing of epoxy resin insulation systems used for encapsulating dry type cast distribution transformer coils is disclosed. The internal method uses a Direct-Current (DC) power source to control and supply DC current to resistively heat the transformer coil encapsulated with a liquid resin under vacuum in a mold. DC current is applied to a given coil based on its conductor cross-sectional area and its epoxy resin quantity to achieve a specified temperature for drying, gelling and final curing. The temperature, controlled by DC resistive heating is maintained for a given period for each step.