Process for manufacturing a polymeric encapsulated transformer

• US 5,036,580 A
• Filed: 09/21/1990
• Issued: 08/06/1991
• Est. Priority Date: 03/14/1990
• Status: Expired due to Fees

• Current Assignee: Virginia Tech Foundation, Inc. (Virginia Polytechnic Institute and State University)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Sheer, M. Lana, Fox, Lloyd
• Primary Examiner(s): Hall, Carl E.
• Application Number:
  US07/586,172
• Time in Patent Office: 319 Days
• Field of Search: 29/605, 29/606, 29/609, 264/272.19, 264/272.13, 336/96
• US Class Current: 29/605
• CPC Class Codes: H01F 2027/328 Dry-type transformer with encapsulated foil winding, e.g. windings coaxially arranged on core legs with spacers for cooling and with three phases
• CPC Class Codes: H01F 41/005 Impregnating or encapsulating insulating of windings H01F41/12
• CPC Class Codes: Y10T 29/49071 by winding or coiling
• CPC Class Codes: Y10T 29/49073 by assembling coil and core
• CPC Class Codes: Y10T 29/49078 Laminated

Abstract

A process for manufacturing a polymeric encapsulated "E" core transformer, a polymeric encapsulated "C" core transformer, and a polymeric encapsulated toroidal shaped transformer, said process requiring considerably less time to complete than do conventional transformer manufacturing processes.

Claims

1. A process for manufacturing a polymeric encapsulated multi-phase transformer having an "E" shaped core consisting essentially of the steps of

(a) forming a stacked laminate structure from trapezoidal or rectangular shaped laminates, said laminates having cut edges, then sealing the cut edges of the stacked laminate structure with a non-conductive film to form a sealed stacked laminate structure, then inserting the sealed stacked laminate structure into a coil form to form a laminate stacked coil form,

(b) heat soaking the laminate stacked coil form at 300°

F. to 450°

F. to form a heat soaked laminate stacked coil form,

(c) encapsulating the inside of the heat soaked laminate stacked coil form with a thermally conductive material to form an encapsulated laminate stacked coil form,

(d) forming a low voltage encapsulated stacked coil form by winding low voltage wires on the encapsulated laminate stacked coil form,

(e) forming a high voltage-low voltage double wall coil bobbin assembly by

(1) inserting the low voltage encapsulated stacked coil form assembly into a molded double wall coil bobbin to form a low voltage double wall coil bobbin assembly and then winding high voltage wire in between the walls of the low voltage double wall coil bobbin assembly to form the high voltage-low voltage double wall coil bobbin assembly or

(2) inserting the low voltage encapsulated stacked coil form into a single wall, single flanged coil bobbin, winding high voltage wire around the wall of the single wall, single flanged coil bobbin, and then placing a molded coil sleeve over the coil bobbin to form the high voltage-low voltage double wall coil bobbin assembly,

(f) heat soaking the high voltage-low voltage coil bobbin assembly at 300°

F. to 400°

F. to form a heat soaked high voltage-low voltage double wall coil bobbin assembly,

(g) encapsulating the inside of the heat soaked high voltage-low voltage double wall coil bobbin assembly with an electrical insulating material to form a first encapsulated high voltage-low voltage double wall coil bobbin assembly having a bottom part and a top part,

(h) repeating steps (a) through (g) above to form a second and third encapsulated high voltage-low voltage double wall coil bobbin assembly,

(i) assembling the "E" shaped core of the multi-phase transformer assembly by

(1) setting the bottom part of the first, second, and third encapsulated high voltage-low double wall coil bobbin assemblies in a perpendicular fashion on the ends and center of a stacked laminate structure formed from trapezoidal or rectangular laminates having cut edges,

(2) securing said stacked laminate structure to the coil bobbin assemblies with a securing device, and

(3) repeating steps (i)(1) and (i)(2) on the top part of the first, second, and third coil bobbin assemblies to form an "E" core multi-phase transformer assembly, and

(4) sealing any unencapsulated cut edges of the laminate stacked structures with a non-conductive film,

(j) arranging the wiring in the "E" core multi-phase transformer assembly and attaching accessories to such transformers,

(k) enclosing the accessories and wires of the "E" core multi-phase transformer assembly between two halves of a thermoplastic wire holder and then sealing the two halves of the thermoplastic wire holders together with a sealant,

(l) heat soaking the "E" core multi-phase transformer assembly of step (k) at 300°

F. to 400°

F., and

(m) encapsulating the heat soaked "E" core multi-phase transformer assembly from step (a) in a thermally conductive material.

2. The process of claim 1 wherein in step (h), only a second high voltage-low voltage double wall coil bobbin assembly is prepared and in step (i), one high voltage-low voltage double wall coil bobbin assembly is set perpendicular on each end of the stacked laminate structure, thereby forming a "C" core multi-phase transformer assembly.

7. The process of claims 1, 3, 4, 5, or 6 wherein the electrical insulating material is selected from the group consisting of 6,6-polyamide, 12,12-polyamide, polybutylene terephthalate, polyphenylene sulfide, and polyethylene terephthalate, and glass reinforced versions thereof.

8. The process of claims 1, 3, 4, 5, or 6 wherein the electrical insulating material is a glass reinforced polyethylene terephthalate thermoplastic molding resin.

9. The process of claims 1, 3, 4, 5, or 6 wherein the thermally conductive material is selected from thermoset and thermoplastic materials comprised of 10% to 70% by weight of a conductive material selected from the group consisting of metallic flake, thermally conductive powder, thermally conductive coke, and thermally conductive carbon fiber.

10. The process of claims 1, 3, 4, 5, or 6 wherein the thermally conductive material is selected from thermoset and thermoplastic materials comprised of 10% to 70% by weight of carbon fiber.

11. The process of claim 9 wherein the thermoplastic or thermoset material is selected from polyethylene terephthalate, polybutylene terephthalate, 6,6-polyamide, 12,12-polyamide, polypropylene, polyphenylene sulfide, and copolyetherester.

12. The process of claim 9 wherein the thermoplastic material is polyethylene terephthalate.

13. The process of claims 1, 3, 4, 5, or 6 wherein the non-conductive film is selected from electrical grade polyethylene terephthalate film and electrical grade polyimide film.

3. A process for manufacturing a polymeric encapsulated single phase transformer having an "E" shaped core consisting essentially of the steps of

(a) preparing a stacked laminate structure wherein the laminates are stamped in the shape of an "E", which "E" shaped laminate has a first end post, a center post, and a second end post, and wherein the laminates have cut edges,

(b) winding low voltage wire on a coil form to form a low voltage coil form,

(c) forming a high voltage-low voltage double wall coil bobbin assembly from the low voltage coil form by

(1) inserting the low voltage coil form into a molded double wall coil bobbin to form a low voltage double wall coil bobbin assembly and then winding high voltage wire in between the walls of the low voltage double wall coil bobbin assembly to form the high voltage-low voltage double wall coil bobbin assembly or

(2) inserting the low voltage coil form into a single wall, single flanged coil bobbin, winding high voltage wire around the wall of the single wall, single flanged coil bobbin, and then placing a molded coil sleeve over the coil bobbin to form the high voltage-low voltage double wall coil bobbin assembly,

(d) heat soaking the high voltage-low voltage coil bobbin assembly at 300°

F. to 400°

F. to form a heat soaked high voltage-low voltage double wall coil bobbin assembly,

(e) encapsulating the inside of the heat soaked high voltage-low voltage double wall coil bobbin assembly with an electrical insulating material to form an encapsulated high voltage-low voltage double wall coil bobbin assembly having a bottom part and a top part,

(f) placing the bottom part of the encapsulated high voltage-low voltage double wall coil bobbin assembly over a post of the "E" shaped laminate stacked structure of step (a),

(g) assembling a laminate stack structure from rectangular shaped laminates having cut edges and attaching the laminate stack structure to the top part of the high voltage-low voltage double wall coil bobbin assembly and the end posts of the "E" shaped laminate stack structure of step (f) to form an "E" core single phase transformer assembly,

(h) arranging the wiring in the "E" core single phase transformer assembly and attaching accessories,

(i) enclosing the accessories and wires of the "E" core single phase transformer assembly between two halves of a thermoplastic wire holder and then sealing the two halves of the thermoplastic wire holders together with a sealant, and then sealing any unencapsulated cut edges of the laminates with a non-conductive film,

(j) heat soaking the "E" core single phase transformer assembly of step (i) at 300°

F. to 400°

F., and

(k) encapsulating the heat soaked "E" core single phase transformer assembly from step (j) in a thermally conductive material.

4. A process for manufacturing a polymeric encapsulated multi-phase transformer having an "E" shaped core consisting essentially of the steps of

(a) preparing a stacked laminate structure wherein the laminates are stamped in the shape of an "E", which "E" shaped laminate has a first end post, a center post, and a second end post, and said laminates have cut edges,

(b) winding low voltage wire on a coil form to form a low voltage coil form,

(c) forming a high voltage-low voltage double wall coil bobbin assembly from the low voltage coil form by

(1) inserting the low voltage coil form into a molded double wall coil bobbin to form a low voltage double wall coil bobbin assembly and then winding high voltage wire in between the walls of the low voltage double wall coil bobbin assembly to form the high voltage-low voltage double wall coil bobbin assembly or

(2) inserting the low voltage coil form into a single wall, single flanged coil bobbin, winding high voltage wire around the wall of the single wall, single flanged coil bobbin, and then placing a molded coil sleeve over the coil bobbin to form the high voltage-low voltage double wall coil bobbin assembly,

(d) heat soaking the high voltage-low voltage coil bobbin assembly at 300°

F. to 400°

F. to form a heat soaked high voltage-low voltage double wall coil bobbin assembly,

(e) encapsulating the inside of the heat soaked high voltage-low voltage double wall coil bobbin assembly with an electrical insulating material to form a first encapsulated high voltage-low voltage double wall coil bobbin assembly having a bottom part and a top part,

(f) repeating steps (a)-(e) to form a second and a third encapsulated high voltage-low voltage double wall coil bobbin assembly, each of which has a bottom part and a top part,

(g) placing the bottom part of the first encapsulated high voltage-low voltage double wall coil bobbin assembly over a post of the "E" shaped laminate stacked structure of step (a), and

(h) repeating step (g) on the remaining posts with the second and third assemblies of step (f),

(i) assembling a laminate stack structure from rectangular shaped laminates and attaching the laminate stack structure to the top part of the high voltage-low voltage double wall coil bobbin assemblies on the "E" shaped laminate stack structure of step (h) to form an "E" core multi-phase transformer assembly,

(j) arranging the wiring in the "E" core multi-phase transformer assembly and attaching accessories,

(k) enclosing the accessories and wires of the "E" core multi-phase transformer assembly between two halves of a thermoplastic wire holder, then sealing the two halves of the thermoplastic wire holders together with a sealant, and then sealing any unencapsulated cut edges of the laminates with a non-conductive film,

(l) heat soaking the "E" core multi-phase transformer assembly of step (k) at 300°

F. to 400°

F., and

(m) encapsulating the heat soaked "E" core multi-phase transformer assembly from step (1) in a thermally conductive material.

5. A process for manufacturing a polymeric encapsulated single or multi-phase transformer having a "C" shaped core consisting essentially of the steps of

(a) (1) preparing a stacked laminate structure wherein the edges of the laminates are cut and wherein the laminates are in the shape of a "C", said "C" form having a first and a second post, or preparing a concentrically wound laminate structure by concentrically winding laminates and then cutting the resultant laminate structure in half, and

(2) sealing the edges of the stacked laminate structure or the concentrically wound laminate structure with a non-conductive film,

(b) winding low voltage wire on a coil form to form a low voltage coil form,

(c) forming a high voltage-low voltage double wall coil bobbin assembly from the low voltage coil form by

(1) inserting the low voltage coil form into a molded double wall coil bobbin to form a low voltage double wall coil bobbin assembly and then winding high voltage wire in between the walls of the low voltage double wall coil bobbin assembly to form the high voltage-low voltage double wall coil bobbin assembly or

(2) inserting the low voltage coil form into a single wall, single flanged coil bobbin, winding high voltage wire around the wall of the single wall, single flanged coil bobbin, and then placing a molded coil sleeve over the coil bobbin to form the high voltage-low voltage double wall coil bobbin assembly,

(d) heat soaking the high voltage-low voltage coil bobbin assembly at 300°

F. to 400°

F. to form a heat soaked high voltage-low voltage double wall coil bobbin assembly,

(e) encapsulating the inside of the heat soaked high voltage-low voltage double wall coil bobbin assembly with an electrical insulating material to form a first encapsulated high voltage-low voltage double wall coil bobbin assembly having a bottom part and a top part,

(f) repeating the processes of steps (b) to (e) to form a second encapsulated high voltage-low voltage coil bobbin assembly,

(g) mounting the bottom part of the first encapsulated high voltage-low voltage coil bobbin assembly on the first post of the "C" stacked or concentrically wound laminate structure of step (a) and mounting the second high voltage-low voltage coil bobbin assembly on the second post of the "C" stacked or concentrically wound laminate structure of step (a),

(h) assembling a laminate stack structure from rectangular shaped laminates and attaching the laminate stack structure to the top part of the first and second encapsulated high voltage-low voltage coil bobbin assembly to form a "C" core single or multi-phase transformer assembly,

(i) arranging the wiring in the "C" core single or multi-phase transformer assembly and attaching accessories,

(j) enclosing the accessories and wires of the "C" core single or multi-phase transformer assembly between two halves of a thermoplastic wire holder and then sealing the two halves of the thermoplastic wire holders together with a sealant,

(k) heat soaking the "C" core single or multi-phase transformer assembly of step (j) at 300°

F. to 400°

F., and

(l) encapsulating the heat soaked "C" core single phase transformer assembly from step (k) in a thermally conductive material.

6. A process for manufacturing a polymeric encapsulated toroidal shaped transformer consisting essentially of the steps of:

(a) preparing circumferential segments of a toroidal shaped core by

(1) preparing a stacked laminate structure wherein the laminates are stamped into the shape of hollow cylinder wafers and stacked together to form circumferential segments of a toroidal core or

(2) convolute winding a metal ribbon into a toroid shape and then separating the resultant metal toroid into circumferential segments of a toroidal core; and

sealing the cut edges of the circumferential segments with a non-conductive film,

(b) winding low voltage wire on a coil form to form a low voltage coil form assembly,

(c) inserting the low voltage coil form assembly into a single wall, single flanged coil bobbin to form a low voltage coil bobbin assembly,

(d) placing a coil sleeve over the low voltage coil bobbin assembly to form a low voltage coil bobbin-coil sleeve assembly,

(e) winding high voltage wire around the outside of the coil sleeve of the low voltage coil bobbin-coil sleeve assembly to form a high voltage-low voltage coil bobbin-coil sleeve assembly,

(f) heat soaking the high voltage-low voltage coil bobbin-coil sleeve assembly to form a heat soaked high voltage-low voltage coil bobbin-coil sleeve assembly,

(g) encapsulating the inside of the heat soaked high voltage-low voltage coil bobbin-coil sleeve assembly with an electrically insulating material to form an insulated encapsulated high voltage-low voltage assembly,

(h) placing one or more of the insulated encapsulated high voltage-low voltage assemblies over the circumferential segments of the toroidal core of step (a) to form assembled toroidal core segments,

(i) bolting, bonding, strapping, or otherwise attaching the assembled toroidal core segments into a toroid to form a single or multi-phase toroidal transformer assembly,

(j) arranging the wiring in the single or multi-phase toroidal transformer assembly in accordance with appropriate codes or standards,

(k) attaching accessories to the single or multi-phase toroidal transformer assembly,

(l) enclosing the accessories and wires of the single or multi-phase toroidal transformer assembly between two halves of a thermoplastic wire holder and then sealing the two halves of the thermoplastic wire holder together at the wire inlets and parting lines with a sealant,

(m) heat soaking the single or multi-phase toroidal transformer assembly of step (l), and

(n) encapsulating the heat soaked single or multi-phase transformer assembly of step (m) in a thermally conductive material.