Molded coil structure

DETAILED DESCRIPTION What is claimed is: 1.
A molded coil structure comprising a coil formed by winding a conductor, a sheet of electrical insulator material respectively wrapped in layers around an inner and an outer periphery of said coil, said layers of insulating material being impregnated with a resin, end-enclosing resin layers covering only end faces of said coil not covered with said layers of insulating material, and a gas charged in an internal space of said coil and sealed therein such that a pressure of the gas is maintained substantially at an atmospheric pressure and the gas uniformly fills the internal space of the coil.
2.
A molded coil structure as claimed in claim 1, wherein said insulating material is a fibrous material having the resin impregnated therein, said layers of insulating material are respectively wrapped around the inner and outer peripheries of said coil so as to extend a short distance beyond the end faces of said coil, and said end-enclosing resin layers are disposed in spaces defined between said layers of insulating material and th respective end faces of said coil.
3.
A molded coil structure as claimed in claim 1 or 2, wherein said end-enclosing resin layers are provided by setting a resin in putty form by heat.
4.
A molded coil structure as claimed in one of claims 1 or 2, wherein said end-enclosing resin layers include gas passage means for communicating the internal space of said coil with the atmosphere so as to maintain the pressure of said gas at atmospheric pressure.
5.
A molded coil structure as claimed in claim 4, wherein said gas passage means is a pipe of a heat-resistive material.




Description:
This invention relates to a molded coil structure in a resin-molded transformer.
A resin-molded transformer employing a thermosetting resin for the electrical insulation of its coils has various merits including ease of maintenance and inspection, high reliability of insulation and incombustibility, and, therefore, there is an ever-increasing demand for such a transformer