Integral mold for a transformer having a non-linear core
View Patent ↗A three-phase non-linear dry-type transformer has integral molds formed of a glass fiber-reinforced polymeric material. The low voltage coil is comprised of an inner low voltage mold formed around each of the at least three core legs, a low voltage conductor winding wound upon the inner low voltage mold and an outer low voltage mold formed around the low voltage winding. The high voltage coil is comprised of an inner high voltage mold disposed around the outer low voltage mold, a high voltage conductor winding wound upon the inner high voltage mold, and an outer high voltage mold formed around the high voltage conductor winding. An annular space between the inner and outer high voltage molds and the inner and outer low voltage molds is filled by an insulating polymeric material during a casting process. The molds are bonded to the coil windings by the insulating polymeric material and remain during the operation of the non-linear transformer as integral components of the non-linear transformer.
1. A three-phase non-linear transformer, comprising:
a ferromagnetic core having at least three core legs arranged in a non-linear configuration;
coil assemblies mounted to said at least three core legs, respectively, each of said coil assemblies comprising:
a generally cylindrical inner low voltage mold disposed around each of said at least three core legs, respectively;
a low voltage winding wound on said inner low voltage mold;
an outer low voltage mold disposed around said low voltage winding;
a dielectric polymeric material encapsulating said low voltage winding; and
a high voltage winding wound around said outer low voltage mold; said outer low voltage mold positioned so that an annular space exists between said inner and outer low voltage molds, said annular space filled by said dielectric polymeric material, said inner and outer low voltage molds remaining in place during the operation of said non-linear transformer.
2. The non-linear transformer of claim 1 further comprising an outer high voltage mold formed around an outer surface of said high voltage winding, said inner high voltage mold and said outer high voltage mold separated by an annular space.
3. The non-linear transformer of claim 2 further comprising a casing encapsulating said high voltage winding, said casing comprising a dielectric polymeric material, said dielectric polymeric material filing said annular space between said inner high voltage mold and said outer high voltage mold.
4. The non-linear transformer of claim 1 wherein said least three core legs are arranged in a triangular configuration.
5. The non-linear transformer of claim 2 wherein said inner and outer high and low voltage molds are formed of a sheet of non-conductive material.
6. The non-linear transformer of claim 5 wherein said non-conductive material is a glass fiber-reinforced polyester resin.
7. The non-linear transformer of claim 2 wherein at least one of said inner and outer high and low voltage molds is formed of two segments.
8. The non-linear transformer of claim 3 wherein said outer high voltage mold comprises first and second longitudinal ends each having a an edge surface from which a flange extends, said first and second longitudinal ends having a gap extending therebetween.
9. The non-linear transformer of claim 8 wherein said gap between said first and second longitudinal ends houses at least one tap and is filled of a dielectric polymeric material except for a top surface of said at least one tap.
10. The non-linear transformer of claim 9 wherein said dielectric polymeric material is an epoxy resin.
11. The non-linear transformer of claim 2 wherein the annular space between said high and low voltage molds is end-filled with a polymeric material.