Method of making tubular coils with cooling and insulating channels

Claim 1

A method of making a hollow dry insulated multi-layer series-connected air-cooled coil, which is highly resistant to impulse voltages, the steps comprising: a. on a form, winding a predetermined number of alternate layers of thin sheet insulation capable of absorbing liquid resin and turns of a single conductor; b. supporting on the thus-wound layers, a plurality of elongated equi-circumferentially spaced duct forming cloth-wrapped molds each having a cross-section which is a section of a torus with the section having rounded ends; c. continuing winding alternate layers of said thin sheet insulation and additional turns of said conductor around the assembly of molds and underlying layers of insulation and conductor; d. repeating the foregoing steps until the desired number of layers and molds is complete; e. vacuum casting the completed assembly with a high dielectric constant high quality resin to completely permeate the sheet insulation and cloth wrapping; f. curing said resin to form a unitary laminate with said cloth and insulation; and g. removing said form and molds, the radial dimension of said ducts defining the radial air spacing between layers of the coil and being about ten to twenty times the solid insulation spacing between adjacent conductors in the same layer and the solid insulation between the coils and the adjacent duct which latter dimension is held to between 0.5 and 1.0 mm.

Claim 2

A method of making a hollow dry insulated multi-layer series-connected air-cooled coil, which is highly resistant to impulse voltages, the steps comprising: a. on a form, winding a predetermined number of alternate layers of thin sheet insulation capable of absorbing liquid resin and turns of a single conductor; b. supporting on the thus-wound layers, a plurality of elongated equi-circumferentially spaced duct forming cloth-wrapped molds each having a cross-section which is a section of a torus with the section having rounded ends; c. continuing winding alternate layers of said thin sheet insulation and additional turns of said conductor around the assembly of molds and underlying layers of insulation and conductor; d. repeating the foregoing steps until the desired number of layers and molds is complete; e. vacuum casting the completed assembly with a high dielectric constant high quality resin to completely permeate the sheet insulation and cloth wrapping; f. curing said resin to form a unitary laminate with said cloth and insulation; and g. removing said form and molds, the radial dimension of said ducts defining the radial air spacing between layers of the coil and being about ten to twenty times the solid insulation spacing between adjacent conductors in the same layer and the solid insulation between the coils and the adjacent duct which latter dimension is held to between 0.5 and 1.0 mm.

Claim 3

A method of making a hollow dry insulated multi-layer series-connected air-cooled coil, which is highly resistant to impulse voltages, the steps comprising: a. on a form, winding a predetermined number of alternate layers of thin sheet insulation capable of absorbing liquid resin and turns of a single conductor; b. supporting on the thus-wound layers, a plurality of elongated equi-circumferentially spaced duct forming cloth-wrapped molds each having a cross-section which is a section of a torus with the section having rounded ends; c. continuing winding alternate layers of thin sheet insulation and additional turns of said conductor around the assembly of molds and underlying layers of insulation and conductor; d. repeating the foregoing steps until the desired number of layers and molds is complete; e. vacuum casting the completed assembly with a high dielectric constant high quality resin to completely permeate the sheet insulation and cloth wrapping; f. curing said resin to form a unitary laminate with said cloth and insulation; and g. removing said form and molds, the radial dimension of said ducts defining the radial air spacing between layers of the coil of a few millimeters and the solid insulation between the coils and the adjacent duct is between 0.5 and 1.0 mm.

Claim 4

A method of making a hollow dry insulated multi-layer series-connected air-cooled coil, which is highly resistant to impulse voltages, the steps comprising: a. on a form, winding a predetermined number of alternate layers of thin sheet insulation capable of absorbing liquid resin and turns of a single conductor; b. supporting on the thus-wound layers, a plurality of elongated equi-circumferentially spaced duct forming cloth-wrapped molds each having a cross-section which is a section of a torus with the section having rounded ends; c. continuing winding alternate layers of thin sheet insulation and additional turns of said conductor around the assembly of molds and underlying layers of insulation and conductor; d. repeating the foregoing steps until the desired number of layers and molds is complete; e. vacuum casting the completed assembly with a high dielectric constant high quality resin to completely permeate the sheet insulation and cloth wrapping; f. curing said resin to form a unitary laminate with said cloth and insulation; and g. removing said form and molds, the radial dimension of said ducts defining the radial air spacing between layers of the coil of a few millimeters and the solid insulation between the coils and the adjacent duct is between 0.5 and 1.0 mm.