Transformer

Abstract

This transformer (100) comprises: a winding core (41); a winding (42), a dislocation wire (42a) of which is spirally wound around the winding core (41); a holding band (43) that holds one end part of the winding (42) along the dislocation wire (42a) at the one end part in the winding core (41); a holding band (44) that holds the other end part of the winding (42) along the dislocation wire (42a) at the other end part in the winding core (41); and a pressing mechanism (8) that presses one of the holding band (43) and the holding band (44) toward the other. The other of the holding band (43) and the holding band (44) is fixed to the winding core (41), and a secondary coil (4) formed by the winding core (41) and the winding (42) is disposed such that the axis thereof is oriented in a horizontal direction.

Description

transformer

[0001] The present disclosure relates to transformers.

[0002] Conventionally, as disclosed in Patent Document 1, for example, a transformer using transposed wires for windings has been known. Generally, in such a transformer, the coil is arranged with its axis oriented vertically. During the assembling stage of the transformer, the coil is arranged upright with its axis oriented vertically for inserting the iron core, and the coil maintains this orientation even after the transformer is completed.

[0003] Japanese Patent Publication No. 2001-143937

[0004] In recent years, power supply voltage transformers, which apply voltage transformer technology, have been attracting attention. Power supply voltage transformers are transformers that transform high voltages in power systems to low voltages. In such transformers, the coil is arranged so that its axis is aligned horizontally. Like the coil in the above-mentioned transformer, this coil is arranged upright with its axis facing vertically during the transformer assembly process, for example, to insert the iron core. However, the coil of this transformer is installed in a container with its axis facing horizontally.

[0005] In transformers that use small coils, such as potential transformers used in voltage measurement, the coils are light, so even if the coil position is changed as described above, the coil windings are less likely to become misaligned or loose.

[0006] In contrast, power supply voltage transformers use transposed wires with large thickness and width in the windings, which makes the coils heavy. Therefore, when the coil position is changed as described above, the heavy windings are more likely to shift and become loose.

[0007] An object of one aspect of the present disclosure is to make it difficult for misalignment and loosening of windings to occur due to changes in the posture of a coil using transposed wires for its windings.

[0008] In order to solve the above problems, a transformer according to one aspect of the present disclosure includes a winding core, a winding in which a transposed electric wire is wound spirally around the winding core, a first holding member that holds one end of the winding on the winding core along the transposed electric wire, a second holding member that holds the other end of the winding on the winding core along the transposed electric wire, and a pressing mechanism that presses one of the first holding member and the second holding member toward the other, wherein the other of the first holding member and the second holding member is fixed to the winding core, and a coil formed by the winding core and the winding is arranged with its axis oriented horizontally.

[0009] According to one aspect of the present disclosure, it is possible to make it difficult for misalignment and loosening of the windings that occur due to changes in the posture of a coil that uses transposed wires for its windings to occur.

[0010] Fig. 1 is a front view showing the configuration of a transformer according to an embodiment of the present disclosure; Fig. 2 is a side view showing the configuration of the transformer; Fig. 3 is a plan view showing the configuration of a secondary coil in the transformer; Fig. 4 is a perspective view showing the configuration of a winding core in the secondary coil; Fig. 5 is a view showing the secondary coil in a state where an iron core is inserted in such a position that the axis of the secondary coil is oriented vertically.

[0011] An embodiment of the present disclosure will be described in detail below.

[0012] <Configuration of Transformer> Fig. 1 is a front view showing the configuration of a transformer 100 according to this embodiment. Fig. 2 is a side view showing the configuration of the transformer 100.

[0013] 1 and 2, the transformer 100 includes a container 1, a primary coil 2, a connecting conductor 3, a secondary coil 4, an iron core 5, core fasteners 6 and 7 (rotation prevention structure), and a pressing mechanism 8. The transformer 100 is configured as, for example, a power voltage transformer (PVT) that converts the high voltage of a power system to a low voltage.

[0014] The container 1 houses a primary coil 2, a connecting conductor 3, a secondary coil 4 (coil), an iron core 5, core fasteners 6 and 7, and a pressing mechanism 8. The container 1 has a lower portion 1a, an upper portion 1b, and an insulating spacer 1c. Inside the container 1, SF is used as an insulating medium. ６ The container 1 is filled with a gas such as a gas. Note that the container 1 may also be filled with other insulating media such as dry air or insulating oil.

[0015] A base 1d is provided at the lower end of the outer wall surface of the lower portion 1a on the floor for placing the transformer 100. In addition, at least four supports 1e are provided at the lower end of the inner wall surface of the lower portion 1a for supporting the core fasteners 6 and 7.

[0016] The upper portion 1b is formed so as to cover the lower portion 1a. The upper portion 1b is connected to the lower portion 1a by fastening bolts. The upper portion 1b has an opening at its upper end. The insulating spacer 1c is formed so as to close the opening of the upper portion 1b. The insulating spacer 1c is connected to the upper portion 1b by fastening bolts.

[0017] The primary coil 2 is arranged with its axis oriented horizontally. The primary coil 2 is formed in a cylindrical shape. The primary coil 2 is formed by being wound around a cylindrical winding core 2a. The outer periphery of the primary coil 2 is covered with a high-voltage shield 2b.

[0018] The connecting conductor 3 is a conductor that connects the insulating spacer 1c and the primary coil 2. The upper end of the connecting conductor 3 is connected to the insulating spacer 1c. The lower end of the connecting conductor 3 is connected to the upper end of the primary coil 2.

[0019] The secondary coil 4 is arranged so that its axis faces the horizontal direction. The secondary coil 4 is arranged so that it is fitted inside the winding core 2 a of the primary coil 2 so that its axis coincides with the axis of the primary coil 2.

[0020] The iron core 5 is a laminated iron core formed by stacking a plurality of steel plates, and has an upper yoke portion 5a, a lower yoke portion 5b, a first leg portion 5c, and a second leg portion 5d.

[0021] The upper yoke portion 5a is arranged horizontally so that a portion of it is inserted inside the secondary coil 4. The lower yoke portion 5b is arranged horizontally below the upper yoke portion 5a so as to face the upper yoke portion 5a. The first leg portion 5c has an upper end joined to one end of the upper yoke portion 5a and a lower end joined to one end of the lower yoke portion 5b. The second leg portion 5d has an upper end joined to the other end of the upper yoke portion 5a and a lower end joined to the other end of the lower yoke portion 5b.

[0022] The core fasteners 6, 7 are fasteners that fasten the iron core 5 in the lamination direction of the steel plates. The core fasteners 6, 7 are formed from high-strength steel, such as light-gauge steel. Two core fasteners 6, 7 are provided. The pair of core fasteners 6 are fixed to one support base 1e at a distance from each other so as to sandwich the iron core 5 therebetween. The pair of core fasteners 7 are fixed to the other support base 1e at a distance from each other so as to sandwich the iron core 5 therebetween. As will be described later, the core fasteners 6, 7 function as a rotation prevention structure that prevents rotation of the secondary coil 4.

[0023] One core fastener 6 is disposed along each of the ends of the upper yoke portion 5a and the lower yoke portion 5b and the first leg portion 5c of the iron core 5. One core fastener 7 is disposed along each of the ends of the upper yoke portion 5a and the lower yoke portion 5b and the second leg portion 5d of the iron core 5. The core fasteners 6 and 7 fasten the iron core 5 by tightening bolts and nuts.

[0024] The pressing mechanism 8 is a mechanism that presses the holding band 44 of the secondary coil 4 toward the holding band 43. The pressing mechanism 8 will be described in detail later.

[0025] <Details of Secondary Coil> Fig. 3 is a plan view showing the configuration of the secondary coil 4. Fig. 4 is a perspective view showing the configuration of the winding core of the secondary coil 4.

[0026] As shown in FIG. 3 , the secondary coil 4 has a winding core 41, a winding 42, a holding band 43 (first holding member), a holding band 44 (second holding member), a fixed member 45, a moving member 46, and a coating film 47.

[0027] The winding core 41 is a cylindrical part made of an insulating material. Fiber-reinforced plastic (FRP) is a preferred insulating material. This is because, when gas is used as the insulating medium as described above, it is not preferred to use a paper material such as pressboard, which contains moisture in the gas atmosphere. When an insulating medium other than gas is used, the winding core 41 is made of a material appropriate for the insulating medium. For example, when insulating oil is used as the insulating medium, the winding core 41 is preferably made of the above-mentioned pressboard.

[0028] As shown in Figure 4, the winding core 41 has a main body 41a and a protruding portion 41b. The main body 41a has a cylindrical shape. The winding 42 is provided on the outer peripheral surface of the main body 41a. The protruding portions 41b are formed so as to protrude from both ends of the main body 41a in the direction of the central axis (axial direction) of the main body 41a. The protruding portions 41b are provided on the same side of the central axis of the main body 41a. The protruding portions 41b are formed in a curved shape that forms part of the same cylindrical shape as the main body 41a, and have a predetermined width.

[0029] The winding core 41 is arranged so that the two protruding portions 41b are located on the upper side and both side edges of the protruding portions 41b are spaced slightly apart from the core fasteners 6 and 7. The winding core 41 may also be arranged so that both side edges of the protruding portions 41b abut against the core fasteners 6 and 7. The winding core 41 may also be arranged so that the two protruding portions 41b are located on the lower side.

[0030] The protrusion 41b may be provided on either one of the ends of the main body 41a. The protrusion 41b may also be provided on a different side of the central axis of the main body 41a. For example, one of the two protrusions 41b shown in FIG. 4 is provided on the lower side.

[0031] The winding 42 is formed by spirally winding a transposed electric wire 42a around the main body 41a of the winding core 41. The transposed electric wire 42a is an electric wire formed by continuously transposing a plurality of rectangular electric wires. The transposed electric wire 42a is wound around the main body 41a either in a state where multiple wires are closely spaced in parallel, or as a single wire.

[0032] The retaining band 43 is positioned along the transposed wire 42a at one end of the winding 42 on the main body 41a of the winding core 41 and holds that end. The retaining band 43 has a thickness similar to that of the transposed wire 42a. When gas is used as the insulating medium, the retaining band 43 is made of a hard resin material. The retaining band 43 is fixed to the outer peripheral surface of the main body 41a with an adhesive or the like. When an insulating medium other than gas is used, the retaining band 43 is made of a material appropriate for the insulating medium, just like the winding core 41. For example, when insulating oil is used as the insulating medium, the retaining band 43 is preferably made of the above-mentioned pressboard.

[0033] The retaining band 43 has a cylindrical shape that fits around the outer circumferential surface of the main body 41a, with a notch 43a (second notch) formed in it. The notch 43a is formed so as to continue from a notch 45a of the fixing member 45, which will be described later, and is cut out along the axial direction of the winding core 41. The notch 43a forms an introduction path through which the transposed wire 42a is introduced at the start of winding of the winding 42.

[0034] One end face of the retaining band 43 is formed so as to be perpendicular to the central axis of the retaining band 43. The other end face of the retaining band 43, which holds the transposed electric wire 42a, is formed in a spiral shape that follows the spiral locus of the transposed electric wire 42a. Therefore, the retaining band 43 is formed so that its width gradually increases from the position where the transposed electric wire 42a starts to be wound to the position where the transposed electric wire 42a has been wound approximately one turn.

[0035] The retaining band 44 is arranged along the transposed electric wire 42a at the other end of the winding 42 on the main body 41a of the winding core 41 and holds the other end. The retaining band 44 has a thickness approximately the same as that of the transposed electric wire 42a. The retaining band 44 is made of a hard resin material. The retaining band 44 is attached to the outer circumferential surface of the main body 41a so that it can slide relative to the outer circumferential surface of the main body 41a and thereby move in the axial direction of the winding core 41.

[0036] The retaining band 44 has a cylindrical shape that follows the outer circumferential surface of the main body 41a and has a notch 44a (second notch) formed in it. The notch 44a is formed so as to continue from a notch 46a of a moving member 46 (described later) and is cut out along the axial direction of the winding core 41. The notch 44a forms a lead-out path for the winding end of the transposed electric wire 42a. The width of the notch 43a of the retaining band 43 may be the same as or different from the width of the notch 43a of the retaining band 43.

[0037] One end face of the retaining band 44 is formed so as to be perpendicular to the central axis of the retaining band 44. The other end face of the retaining band 44, which holds the transposed electric wire 42a, is formed in a spiral shape that follows the spiral locus of the transposed electric wire 42a. For this reason, the retaining band 44 is formed so that its width gradually narrows from a position approximately one turn before the end of the winding of the transposed electric wire 42a to the position where the winding of the transposed electric wire 42a ends.

[0038] The multiple transposed wires 42a arranged in parallel are wide. Therefore, by being shaped as described above, the retaining band 43 can hold the end of the winding 42 without creating a gap due to a one-turn misalignment at the start of the winding of the transposed wire 42a. Also, by being shaped as described above, the retaining band 44 can hold the end of the winding 42 without creating a gap due to a one-turn misalignment at the end of the winding of the transposed wire 42a.

[0039] The fixing member 45 is provided on the end side of the main body 41a where the holding band 43 is arranged so as to come into contact with the holding band 43. The fixing member 45 is fixed to the outer peripheral surface of the main body 41a with an adhesive or the like.

[0040] The fixing member 45 has a cylindrical shape that fits along the outer circumferential surface of the main body 41a, with a notch 45a (first notch) formed in it. The notch 45a is cut out in the axial direction of the winding core 41. The notch 45a, together with the notch 43a of the holding band 43, forms a lead-in path for the start of winding of the transposed electric wire 42a.

[0041] The moving member 46 is provided on the end side of the main body 41 a where the retaining band 44 is arranged so as to come into contact with the retaining band 44. The moving member 46 is attached to the outer circumferential surface of the main body 41 a so as to be movable in the axial direction of the winding core 41 by sliding relative to the outer circumferential surface of the main body 41 a.

[0042] The moving member 46 has a cylindrical shape that follows the outer circumferential surface of the main body 41a and has a notch 46a (first notch) formed in it. The notch 46a is cut out in the axial direction of the winding core 41. The notch 46a, together with the notch 44a of the holding band 44, forms a lead-out path for the winding end of the transposed electric wire 42a. The width of the notch 45a of the fixed member 45 and the width of the notch 46a of the moving member 46 may be the same or different.

[0043] The covering film 47 is provided to cover the surface of the winding 42 in order to protect the winding 42. The covering film 47 is formed of an insulating film, tape, or the like.

[0044] 3, the pressing mechanism 8 is configured to include a core fastener 7 and a fastening mechanism 9. The core fastener 7 has a facing portion 7a that faces the moving member 46. The fastening mechanism 9 has a bolt 91 and nuts 92 to 94.

[0045] The bolt 91 has a shaft portion 91a and a head portion 91b. The shaft portion 91a is inserted into a tapped through hole (not shown) provided in the opposing portion 7a of the core fastener 7. The shaft portion 91a is arranged to face the axial direction of the winding core 41. The head portion 91b is provided at the tip of the shaft portion 91a on the moving member 46 side. The head portion 91b has a main portion and an abutment portion. The main portion has a regular hexagonal prism shape. The abutment portion is provided on the side of the main portion facing the moving member 46 and is formed in a disk shape with an area larger than the area of ​​a cross section perpendicular to the axial direction of the main portion.

[0046] The nut 92 is fitted onto the shaft portion 91a so as to contact the surface of the opposing portion 7a of the core fastener 7 that is farther from the moving member 46. The nut 93 is fitted onto the shaft portion 91a so as to contact the nut 92. The nut 94 is fitted onto the shaft portion 91a so as to contact the surface of the opposing portion 7a that is closer to the moving member 46. The nut 94 is tightened so as to contact the opposing portion 7a, thereby fixing the bolt 91 to the opposing portion 7a.

[0047] The position of the head 91b in the axial direction of the core 41 can be adjusted depending on the fastening position of the main body of the head 91b and the fastening position of at least one of the nuts 92, 93 on the shaft 91a. This makes it possible to adjust the amount by which the pressing mechanism 8 presses the moving member 46 and the retaining band 44 (pressing amount). Specifically, when the fastening position of at least one of the head 91b (main body) and the nut 93 is adjusted so that the head 91b moves in the direction of arrow A shown in FIG. 3, the pressing amount increases. On the other hand, when the fastening position of at least one of the head 91b (main body) and the nut 92 is adjusted so that the head 91b moves in the direction of arrow B shown in FIG. 3, the pressing amount decreases.

[0048] The winding 42 wound with the transposed electric wire 42 a is prone to have an increased overall winding width due to misalignment and slack in the transposed electric wire 42 a. In response to this, by adjusting the amount of pressure as described above, the dimension by which the moving member 46 is pressed can be appropriately controlled in accordance with the overall winding width of the winding 42 on the winding core 41.

[0049] In the above description, the retaining band 43 is referred to as the "first retaining member" and the retaining band 44 as the "second retaining member." Alternatively, the retaining band 43 may be referred to as the "second retaining member" and the retaining band 44 as the "first retaining member." In this case, however, the fixed member 45 is provided on the retaining band 44 side, and the moving member 46 is provided on the retaining band 43 side. Accordingly, the pressing mechanism 8 is provided on the moving member 46 side.

[0050] <Manufacturing of Transformer> FIG. 5 is a diagram showing the secondary coil 4 in a state where the iron core 5 is inserted in such a position that the axis of the secondary coil 4 faces vertically.

[0051] First, the holding band 43 and the fixing member 45 are fixed to the outer peripheral surface of the main body 41 a of the core 41 .

[0052] 4, the winding core 41 is placed with its axis oriented horizontally, and a frame (not shown) is fitted inside the winding core 41, and the frame is then attached to a winding machine (not shown). The frame holds the winding core 41 from the inside to prevent the winding core 41 from deforming due to the winding of the transposed electric wire 42a, thereby maintaining the shape of the winding core 41.

[0053] Then, while rotating the winding core 41 around its axis using a winding machine, the transposed wire 42a is wound around the outer circumferential surface of the main body 41a, starting from the position of the retaining band 43. Once the winding 42 is formed on the main body 41a, a retaining band 44 and a moving member 46 are attached to the outer circumferential surface of the main body 41a. The surface of the winding 42 is then covered with a coating film 47, thereby completing the secondary coil 4.

[0054] 5, with the secondary coil 4 standing with its axis facing vertically, the upper yoke portion 5a of the core 5, excluding the second leg portion 5d, is inserted into the secondary coil 4 (winding core 41). At this time, multiple hooks to which wires are attached are engaged with fixing members 45, and the secondary coil 4 is suspended from above by the wires. The secondary coil 4 is lowered from above so that the winding core 41 covers the standing upper yoke portion 5a, thereby inserting the upper yoke portion 5a into the secondary coil 4.

[0055] Thereafter, with the core fastener 6 attached to the iron core 5, the primary coil 2 is lowered from above onto the upright secondary coil 4, thereby fitting the secondary coil 4 inside the winding core 2a. With the secondary coil 4 thus assembled into the primary coil 2, the second leg 5d is joined to the iron core 5, and the core fastener 7 is attached to the iron core 5.

[0056] By arranging the secondary coil 4 as described above, the moving member 46 approaches the pressing mechanism 8, allowing the pressing mechanism 8 to press against the moving member 46. When arranging the secondary coil 4, the head 91b of the bolt 91 in the pressing mechanism 8 is set back in the direction of arrow B in Figure 3 so as not to interfere with the arrangement. Once the secondary coil 4 is arranged, the position of the head 91b is moved in the direction of arrow A in Figure 3 by adjusting the fastening position of the head 91b (main body) of the fastening mechanism 9 and the nut 93. In this way, the amount of pressing by the pressing mechanism 8 is adjusted so that the dimension pressing against the moving member 46 becomes an appropriate value.

[0057] After adjusting the amount of pressure, the primary coil 2, secondary coil 4, iron core 5 and core fasteners 6, 7 are rotated and assembled into the container 1 so that the axial directions of the primary coil 2 and secondary coil 4 are oriented horizontally.

[0058] <Effects of the Transformer> As described above, the transformer 100 includes the holding bands 43, 44 and the pressing mechanism 8. The holding band 43 holds one end of the winding 42 on the winding core 41 along the transposed wire 42a. The holding band 44 holds the other end of the winding 42 on the winding core 41 along the transposed wire 42a. The pressing mechanism 8 presses the holding band 44 toward the holding band 43.

[0059] As a result, one end of the winding 42 is held by the holding band 43 along the transposed electric wire 42a, and the other end of the winding 42 is held by the holding band 44 along the transposed electric wire 42a. This prevents the position of the transposed electric wire 42a at both ends of the winding 42 from shifting. In addition, the holding band 44 is pressed toward the holding band 43 fixed to the winding core 41. As a result, the winding 42 is pressed in the axial direction of the winding core 41 and is held in a tight state. Therefore, even if the orientation of the secondary coil 4 changes so that the axis of the secondary coil 4 faces from the vertical direction shown in FIG. 5 to the horizontal direction shown in FIG. 1, the winding 42 is less likely to shift or loosen.

[0060] The winding core 41 has protrusions 41b. The protrusions 41b have a predetermined width and are provided so as to protrude from both ends of the main body 41a in the axial direction of the winding core 41. The transformer 100 also includes core fasteners 6 and 7. The core fasteners 6 and 7 function as a rotation prevention structure that prevents circumferential rotation of the secondary coil 4 by contacting the protrusions 41b.

[0061] When the transformer 100 is moved, for example, for transportation, the secondary coil 4 may become heavy and easily rotate. In such a case, the protrusion 41b, which tends to rotate together with the secondary coil 4, abuts against the core fasteners 6 and 7, thereby preventing the secondary coil 4 from rotating. This prevents the secondary coil 4 from rotating.

[0062] The transformer 100 includes a pressing mechanism 8. The pressing mechanism 8 is capable of adjusting the amount of pressure applied to the retaining band 44. This allows the amount of pressure applied to the retaining band 44 to be appropriately controlled in accordance with the overall winding width of the winding 42 on the winding core 41.

[0063] The transformer 100 includes a moving member 46. The moving member 46 contacts the retaining band 44 and is provided on the outer peripheral surface of the main body 41a of the winding core 41 so as to be movable in the axial direction of the winding core 41. The pressing mechanism 8 is configured by including a fastening mechanism 9 having a core fastener 7 and a bolt 91. The bolt 91 is held by the core fastener 7 so as to be movable back and forth in the axial direction of the winding core 41. A head 91b provided at the tip of the bolt 91 abuts against the moving member 46.

[0064] As a result, when the bolt 91 advances toward the moving member 46 relative to the core fastener 7, the moving member 46 is pushed by the head 91b and moves. Also, when the bolt 91 retreats away from the moving member 46 relative to the core fastener 7, the moving member 46 is pushed back by the elastic force that attempts to restore the original shape of the winding 42 formed by the transposed wire 42a. In this way, by adjusting the amount of advancement and retreat of the bolt 91, the above dimensions can be appropriately controlled.

[0065] The transformer 100 includes a fixing member 45. The fixing member 45 is provided on the end side of the main body 41 a of the winding core 41 where the retaining band 43 fixed to the winding core 41 is arranged, and is fixed to the outer peripheral surface of the main body 41 a.

[0066] As a result, when assembling the transformer 100, the secondary coil 4 can be hung by a wire attached to the fixing member 45 with the fixing member 45 positioned below when inserting the secondary coil 4 into the upper yoke portion 5a of the iron core 5. Therefore, the secondary coil 4 can be held in a position with its axis oriented vertically.

[0067] The fixing member 45 has a notch 45 a. The holding band 43 has a notch 43 a. The notch 43 a is formed so as to continue from the notch 45 a. The notches 43 a and 45 a are cut out in the axial direction of the winding core 41.

[0068] The moving member 46 has a notch 46a. The holding band 44 has a notch 46a. The notch 44a is formed so as to continue from the notch 46a. The notches 44a and 46a are cut out in the axial direction of the winding core 41.

[0069] When the winding 42 and the retaining bands 43, 44 are covered with the covering film 47, heat tends to build up inside the covering film 47. In response to this, the cutouts 43a, 44a, 45a, and 46a function as ventilation paths to the winding 42 inside the covering film 47. This improves the heat dissipation of the winding 42.

[0070] [Additional Notes] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. In addition, embodiments obtained by appropriately combining the technical means disclosed in the embodiments are also included in the technical scope of the present disclosure.

[0071] 4 Secondary coil (coil) 6, 7 Core fastening metal fitting (rotation prevention structure) 8 Pressing mechanism 41 Winding core 41b Protrusion 42 Winding 42a Transposed electric wire 43 Holding band (first holding member) 43a Notch portion (second notch portion) 44 Holding band (second holding member) 44a Notch portion (second notch portion) 45 Fixed member 45a Notch portion (first notch portion) 46 Moving member 46a Notch portion (first notch portion) 91 Bolt 91b Head 100 Transformer

Claims

1. A transformer comprising: a winding core; a winding in which a transposed electric wire is wound helically around the winding core; a first holding member that holds one end of the winding on the winding core along the transposed electric wire; a second holding member that holds the other end of the winding on the winding core along the transposed electric wire; and a pressing mechanism that presses one of the first holding member and the second holding member toward the other, wherein the other of the first holding member and the second holding member is fixed to the winding core, and a coil formed by the winding core and the winding is arranged with its axis facing horizontally.

2. A transformer as claimed in claim 1, wherein the winding core has a protruding portion of a predetermined width protruding from at least one end in the axial direction of the winding core, and the transformer further comprises a rotation prevention structure that prevents circumferential rotation of the coil by contact with the protruding portion.

3. A transformer according to claim 1 or 2, wherein the pressing mechanism is capable of adjusting the amount of pressing on either the first holding member or the second holding member.

4. A transformer as described in claim 3, wherein the pressing mechanism comprises: a bolt held by a core fastening fitting that fastens an iron core, a part of which is disposed inside the winding core, so as to be movable back and forth in the axial direction of the winding core; and a moving member that comes into contact with either the first holding member or the second holding member, is provided on the outer peripheral surface of the winding core so as to be movable in the axial direction of the winding core, and against which the tip of the bolt abuts.

5. A transformer as described in claim 4, wherein the moving member has a first cutout portion cut out in the axial direction of the winding core, and either the first holding member or the second holding member has a second cutout portion cut out in the axial direction of the winding core, formed so as to be continuous with the first cutout portion.

6. A transformer as described in claim 1, further comprising a fixing member provided on the end side of the winding core where the other of the first holding member and the second holding member fixed to the winding core is arranged, and fixed to the outer peripheral surface of the winding core.

7. A transformer as described in claim 6, wherein the fixing member has a first cutout portion cut out in the axial direction of the winding core, and the other of the first holding member and the second holding member has a second cutout portion cut out in the axial direction of the winding core, formed so as to be continuous with the first cutout portion.

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