US3170134A

US3170134A - Electrical coil structure for inductive apparatus

Info

Publication number: US3170134A
Application number: US159699A
Authority: US
Inventors: Betty J Palmer
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1961-12-15
Filing date: 1961-12-15
Publication date: 1965-02-16
Anticipated expiration: 1982-02-16
Also published as: CH422145A

Description

Feb. 16, 1965 B. J. PALMER 3,170,134

ELECTRICAL COIL STR UUUUUUUUUUUUUUUUUUUUUUUUU US Fi l e d D e c 1 5 l 9 61 Feb. 16, 1965 a. J. PALMER 3,170,134

ELECTRICAL con. STRUCTURE FOR mnucnvs APPARATUS FilGd D60. 15, 1961 4 Sheets-Sheet 2 Fig. 2.

Feb. 16, 1965 B. J. PALMER 3,170,134

ELECTRICAL COIL STRUCTURE FOR INDUCTIVE APPARATUS Filed Dec. 15, 1961 4 Sheets-Sheet 3 Fig.3.

Feb. 16, 1965 a. J PALMER 3,170,134

ELECTRICAL COIL. STRUCTURE FOR INDUCTIVE APPARATUS Filed Dec. 15, 1961 4 Sheets-Sheet 4 N N 92 N N N I i u i United States Patent Ofiice 3,170,134 Patented Feb. 16, 1965 3,170,134 ELECTRICAL COIL STRUCTURE FOR INDUCTIVE APPARATUS Betty J. Palmer, Sharon, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., 21 corporation of Pennsylvania Filed Dec. 15, 1961, Ser. No. 159,699 Claims. (Cl. 336-205) This invention relates in general to electrical inductive apparatus and more particularly to coils for inductive apparatus such as transformers.

Transformers of the prior art have conventionally used a coil wound on a form made from multiple turns of an insulating paper having a coating of an adhesive on one or both sides of the paper. The process of depositing the adhesive on the insulating paper increases the cost of the coil insulation and, of course, increases the cost of the apparatus.

Accordingly, it is a general object of this invention to provide an improved electrical inductive apparatus, such as a transformer.

It is a more particular object of this invention to provide a new and improved inexpensive coil for electrical inductive apparatus, such as transformers.

Briefly, the present invention accomplishes the above cited objects by providing a coil form wound from an uncoated, thermally stabilized insulating paper. The conductor used to wind the coil may be round or rectangular wire or foil or sheet conductor material. A liquid adhesive is poured into the coil at spaced intervals so that it flows between the several layers of insulation and conductor. The coil is then heated in an oven to cure the adhesive. The liquid adhesive may be either thermosetting or thermoplastic provided it has a sufiiciently high melting point to remain solid at the operating temperature of the apparatus.

Further objects and advantages of the invention will become apparent as the following description proceeds and features of novelty which characterize the invention will be pointed out in particularity in the claims annexed to and forming a part of the specification.

For a better understanding of the invention, reference may be had to the accompanying drawings, in which:

FIGURE 1 is a top view of a transformer coil made in accordance with my invention;

FIG. 2 is a sectional view of another transformer coil made in accordance with my invention;

FIG. 3 is a sectional view taken along the line III-III of FIG. 1; and

FIG. 4 is a sectional view of a modified embodiment of my invention.

The coil illustrated in FIG. 1 is formed by winding a strip of thermally stabilized insulating paper on a mandrel to form an insulating coil form 10. A first section 12 of low voltage winding is wound on the coil form It The low voltage winding is a plurality of turns of copper or aluminum foil or sheet conductor. The foil or sheet conductor used to wind the low voltage winding may be insulated prior to winding, for example, by coating it with an insulating enamel. To further insulate one layer of the winding from an adjacent layer of the winding a strip 14 of insulating material, such as thermally stabilized insulating paper, is wound between each layer or turn of the foil or sheet conductor. The number of turns of the insulated foil or sheet conductor comprising the low voltage winding 12 is, of course, determined by the transformer voltage and current rating desired.

The next layer 16 is thermally stabilized insulating paper wound on top of the last turn of the low voltage winding 12.

A corrugated fibrous strip of material, or a plurality of pressboard or wood strips 18 placed at the ends of the transformer provide a duct 20 for the circulation of a liquid dielectric adjacent to the end turns of the low voltage winding 12. The wood or other insulating strips 18 are glued to the last turn of the insulating tube 16 around the ends of the transformer to provide a space or duct 20 adjacent to the tube 16. This space or duct 26 allows the liquid dielectric to circulate between the low voltage winding 12 and an insulating tube 24.

The insulating tube 24 is formed by winding on top of the tube 16 as many layers of insulating paper as required to insulate the low voltage winding 12 from the high voltage winding. The first or inside section 22 of the high voltage winding is comprised of a plurality of layers of sheet or foil conductor wound on the tube 24 with a turn of thermally stabilized insulating paper between each layer of the conductor.

A strip of corrugated fibrous sheet or a plurality of pressboard or wood strips 26 is placed at the ends of the transformer on the first section 22 of high voltage winding. The corrugated strip 26 provides a plurality of ducts 28 for the circulation of the liquid dielectric between the

sections

22 and 30 of the high voltage winding.

The second section 30 of high voltage winding is Wound in the same manner as the first section 22. That is, alternate layers of conductor and insulating paper are wound on the first section 22 of the high voltage winding with the corrugated fibrous strip 26 therebetween at the ends of the transformer. As many sections of high voltage winding would be used as are required for proper cooling of the winding at the transformer rating desired.

On the last section 32 of high voltage winding another duct 34 is provided, for example, by wood strips 36 affixed thereto, for the circulation of the liquid dielectric adjacent to the last section 32 of the high voltage winding.

Another insulating tube 38 wound, on the last section 32 of the high voltage winding, using thermally stabilized insulating paper provides the necessary insulation between the outside or last section 32 of the high voltage winding and the inside layer 40 of an outside section of the low voltage winding. The outside section of the low voltage winding like the inside section is comprised of two layers 49 and 42 of enamel insulated wire or foil electrical conductor with a layer 44 of thermally stabilized insulating paper between the

layers

40 and 42 of the low voltage winding.

The final layer 46 of material on the coil is a turn of thermally stabilized insulating paper wound on the outside layer 42 of the outside section of the low voltage winding.

After the entire transformer coil is wound a liquid adhesive, such as an epoxy resin, is poured into the transformer at spaced intervals, for example, the

areas

48, 50, 52 and 54 at the four corners, so that it will flow in an axial direction between the multiple layers of the insulation and conductor. The coating of adhesive may extend from one face of the coil completely through the coil, in an axial direction, to the opposite face of the coil. However, when foil or sheet conductor is used only the edges of the foil need to be coated with the adhesive. Coils with adhesive on only the top and bottom, 0.5 inch of foil, were tested and withstood a full short circuit without damage due to movement. The transformer is then heated to a temperature of C. to C. which cures the adhesive poured between the layers of the transformer thereby firmly bonding the plurality of layers of insulation and conductor together to provide a solid coherent unit and prevent axial shifting of the electrical conductors upon short circuiting of the windings of the coil.

A transformer coil having only one section of low transformer coil.

voltage winding and one section of high voltage winding is illustrated in the sectional view of FIG. 2.

Like the transformer coil of FIG. 1, a strip of insulating paper is wound on a mandrel to form a tubular coil form 60. A plurality of turns of metallic foil or sheet electrical conductor is then wound on the coil form 69 to form a first or inside section 62 of low voltage winding. The foil or sheet used to wind the coil is coated with a material such as enamel to provide coil turn-to-turn insulation. A strip of thermally stabilized paper is wound over the first section 62 of low voltage winding to form a tubular insulating member 64 between the

sections

62 and 66 of the low voltage winding. The second section 66 of low voltage winding is, like the first section 62, a strip of enameled sheet or foil conductor wound on the insulating member 64 to form a plurality of turns of the low voltage winding.

Another insulating member 68 is wound from a strip of thermally stabilized paper to provide insulation for the low voltage winding. A duct '70 is then formed at the ends of the coil by a corrugated fibrous strip, or a plurality of pressboard or wood strips 71.

The next layer 72 is another insulating member wound on the member 68 and the duct forming members from the thermally stabilized insulating paper. The num er of turns of paper used to form the member 72 is, of course, determined by the voltage difference between the low voltage winding and the high voltage winding.

The high voltage winding 74 is, like the low voltage winding, Wound from an insulated sheet or foil conductor with a strip of insulating paper between layers of the winding to provide layer-to-layer insulation. The final layer 76 on the single section transformer coil of FIG. 2 is a plurality of turns of thermally stabilized insulating paper. The number of turns is determined by the voltage at whichthe high voltage winding is operated.

A liquid adhesive, for example an epoxy resin, is poured into the completely wound coil at spaced intervals so it will flow between the several turns of insulating paper and sheet or foil conductor. The unit is then placed in an oven and heated to cure the adhesive which permanently sets and firmly bonds the several turns of the apparatus together to provide a rigid coherent unit.

The sectional view of FIG. 3, taken along line IIIHI of FIG. 1, is shown greatly exaggerated to illustrate the small area between each layer or turn of the apparatus where the liquid adhesive can flow. Like reference characters of FIG. 1 and FIG. 3 represent like parts of the The liquid adhesive is poured into the transformer coil at spaced intervals, for example the four corners, and flows between the several layers of the coil. The adhesive flows in an axial direction between the layers of the coil to thereby coat a portion of each turn of the transformer with the liquid adhesive. The transformer coil is then heated to a temperature sufiicient to cure the adhesive and thereby firmly bond each turn of the paper and conductor to the adjacent turn to make a solid coherent transformer coil able to withstand a complete electrical short circuit without damage due to mechanical stress and vibration.

A modified embodiment of this invention is shown in the sectional view of FIG. 4. Like the coil of FIG. 2, a strip of thermally stabilized insulating paper is wound on a mandrel to form a coilform St}. A first section 82 of low voltage winding is wound on the coil form 80. The first section 82 of low voltage winding is a plurality of turns of insulated wire, for example, an enameled rec tangular wire having a coating of an adhesive over the insulation. The coating of adhesive, such as an epoxy resin in the B stage, is non-tacky at ambient temperature, but becomes soft and flows at elevated temperatures and permanently sets when cool. A layer 84 of insulating paper is wound between the first section 82 of the low voltage winding and a second section 36 of the low voltage winding to provide additional layer-to-layer insulation of 4 the low voltage winding. The next layer is a plurality of turns of the thermally stabilized insulating paper wound to form an insulating member 3%. The number of turns of insulating paper used to form insulating member 88 is determined by the voltage difference between the low voltage winding and thehigh voltage winding. A duct 99 is formed on the ends of the coil by placing a corrugated fibrous sheet or a plurality of wood or pressboard strips 91 at spaced intervals around the ends of the transformer between adjacent turns of the insulating member 88. The duct is provided for the circulation of a liquid dielectric adjacent to the low voltage winding.

The next layer 9% is the high voltage winding. The high voltage winding is made from a plurality of turns of a round or rectangular magnet wire 92 having a coating of insulation thereon. The insulated wire has a coating of an adhesive material placed over the insulation. The adhesive is, for example, an epoxy resin coating cured to its B stage prior to winding the wire onto the layer of insulation 88, that is, the adhesive is non-tacky at ambient temperatures, but softens at elevated temperatures and permanently sets when cooled. The high voltage winding has a turn of insulating paper between each layer of wire to provide layer-to-layer insulation of the coil. The paper is folded or cuffed at the end to prevent axial motion of the wire. A final layer of insulation 94 is wound on the high voltage winding from the thermally stabilized insulating paper.

After the entire transformer coil is wound it is removed from the mandrel and a liquid adhesive, such as an epoxy resin, is poured between the layers at spaced intervals around the coil so that it will flow between the layers of insulating paper. The transformer coil is heated to cure the adhesive on the conductor and the adhesive between the layers of the coil. The adhesive on the conductor when heated softens and flows slightiy, then when cooled permanently sets to thereby permanently bond the turns of the conductor together and also firmly bond the layers of the conductor to the layer-to-layer insulating paper. The adhesive poured into the layers of the coil when heated, then cooled, also permanently sets thereby bonding each layer of insulating paper to the adjacent layer of paper. This, of course, firmly bonds the layers of insulating paper and conductors together to a rigid coherent unit able to Withstand a complete electrical short circuit without damage to the transformer due to the vibration of the coil.

While there have been shown and described what are, at present considered to be the preferred embodiments of the invention, modifications thereto will readily occur to those skilled in the art. It is not desired, therefore, that the invention be limited to the specific arrangements shown and described and it is intended to cover in the appended claims all such modifications as fall within the true spiritand scope of the invention.

I claim as my invention:

1. A wound coil having a plurality of turns of insulating and conducting material comprising, a first strip of insulating material wound to provide a coil form, a first winding disposed on said coil form, a second strip of insulating material disposed on said first Winding to form a tubular insulating member, a second winding disposed on said tubular insulating member, and an adhesive disposed between the several turns of said wound coil at spaced intervals around said coil, said adhesive firmly bonding each turn of material to the adjacent turn of material at said spaced intervals.

2. A wound coil having a plurality of layers of insulatingand conducting material comprising, a first tubular insulating member, a first winding disposed on said first tubular insulating member, said first winding being formed from an insulated strip of metallic conductor, a second tubular insulating member disposed on said first winding, a second winding disposed on second insulating member, said second winding being formed from an insulated strip of metallic conductor, and an adhesive disposed between the layers of said metallic conductor and insulating members at spaced intervals around said wound coil, said adhesive firmly bonding the several layers together at said spaced intervals to form a rigid coil.

3. A wound coil having a plurality of layers of insulating and conducting material comprising, a first strip of insulating material wound to provide a coil form, a first winding disposed on said coil form, said first winding being formed from an insulated conductor having a coating of adhesive over the insulation, a second strip of insulating material disposed on said first winding forming a tubular insulating member, a second winding disposed on said tubular insulating member, said second winding being formed from a conductor having a coating of adhesive on top of a coating of insulating material, and an adhesive disposed between said layers of insulating material at spaced intervals around said wound coil, said adhesive firmly bonding the several layers of insulating and conductors together at said spaced intervals 4. A wound coil having a plurality of layers of insulating and conducting material comprising, a first strip of insulating material providing a coil form, a first winding disposed on said coil form, said first Winding being formed from a first strip of metallic foil, a second strip of insulating material disposed on said first winding to form a tubular insulating member thereon, a second winding wound on said tubular insulating member, said second winding being formed from a second strip of metallic foil, and an adhesive disposed between the several layers of insulating material and metallic foil at spaced intervals around said wound coil, said adhesive firmly bonding the layers of the coil together at said spaced intervals.

5. A wound coil for a transformer comprising, a first strip of thermally stabilized insulating paper providing a coil form, a first winding disposed on said coil form, said first winding being formed from an insulated conductor having a coating of adhesive thereon, a second strip of thermally stabilized insulating paper disposed on said first winding to form a tubular insulating member, a second winding disposed on said tubular insulating member, said second winding being formed from an insulated conductor having a coating of adhesive thereon and an epoxy resin adhesive disposed at spaced intervals around said wound coil, said adhesive bonding said insulating paper and conductors together at said spaced intervals to form a solid coherent coil.

References Cited in the file of this patent UNITED STATES PATENTS Rabins Aug. 25, 1961