Abstract:
A method of manufacturing transformer windings embedded in casting resin is disclosed which utilizes an integrated winding mandrel for producing a non-standard oval shaped epoxy encapsulated low voltage coil for dry type distribution transformers. The method includes a process of winding a low voltage coil of alternate layers of copper conductor (24) and insulating tape (26), over a disposable mold formed by wrapping steel sheet material over inner mold support plates (14), the formed mold acting as both a winding mandrel and as an inner mold (20) for epoxy encapsulation. Both the inner and outer molds are made of low cost sheet metal utilizing a 'wrap and band' process. The complete winding and molding processes can all be conducted utilizing a conventional square mandrel shaft (12) on a standard coil winding machine (10).
Abstract:
A method of manufacturing a tranformer coil encapsulated in casting resin utilizing a disposable casting mold where the disposable mold acts both as a winding mandrel and as an inner mold shell (12) for resin encapsulation. The disposable casting mold may be oval shaped or circular shaped depending upon the desired shape of the coils to be encapsulated. The inner (12) and outer (24) mold shells are made from thin sheet metal and thus may be adjusted for the manufacture of a wide variety of sizes of oval shaped or circular shaped epoxy encapsulated coils. The inner mold (12) has flanges (12a) which may be secured mechanically. The ends of theinner mold support bars (18) are connected to spacer bars (20) bybolts. The outer mold (24) is of a one piece construction with an integrated dome and tap area (26). A pre-pregnated glass net (32) may be installed over the finished coil winding to provide anouter layer of glass net which may be applied radially.