JPH04320308A - Circular plate coil winding - Google Patents

Abstract

PURPOSE:To enable an insulation resistance to be maintained and an occupation area to be increased by placing a conductor of an edge portion in one radius direction at an inner-diameter side and an outer-diameter side of a plurality of circular plate coils at a line terminal side at a position which is away in axial direction for the adjacent circular plate coil which is not interlocked at the edge portion. CONSTITUTION:A surface of a side of an oil gap 41A of a reinforced insulator 31 is allowed to match a surface of an edge portion conductor 113 of a winding number 4 of a coil 11A and that of a middle conductor 112 of winding numbers 2 and 3. Then, since an insulation distance between an edge portion conductor 111 and an edge portion conductor 121 is not large from a point of insulation resistance, the middle conductor 112 approaches a circular plate coil 12A by at least a thickness dimension of the reinforced insulator 31, thus enabling the dimension of the oil gap 41A to be reduced by the thickness dimension of the reinforced insulator 31. In this manner, a position in axial direction of the conductor 2 is placed at a position which is shifted to a side of a line terminal 91 by the thickness dimension of the reinforced insulator 31.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention has a capacity of several hundred MV.
Windings connected to ultra-high voltage power systems such as 154 kV or 275 kV of the large capacity transformer A, especially disc coils, are stacked in the axial direction, and the conductors at the inner diameter end or outer diameter end are alternately connected to each other. This invention relates to twin ring-shaped disc windings which are entirely connected in series.

0002

2. Description of the Related Art FIG. 5 is a schematic cross-sectional view of a conventional disc winding wire, with the left side of the figure being the inner diameter side and the right side being the outer diameter side. Most large-capacity transformers are three-winding transformers consisting of a high-voltage winding, a medium-voltage winding, and a low-voltage winding, and the disk winding 100 shown in the figure is a high-voltage transformer connected to a 154 kV or 275 kV system as described above. Often used for high voltage or medium voltage windings.

Terminals 91 and 92 of the disk winding 100 are drawn out from the upper and lower ends, and the three-phase windings are connected in a star shape. A terminal 91 at the upper end is a line terminal connected to an ultra-high voltage system, and a terminal 92 is a neutral point terminal connected to terminals of other phases to form a neutral point. In this figure, the U-phase low-voltage winding of a three-phase transformer, which is a typical large-capacity transformer, is shown.
Therefore, the phase symbol of the line terminal 91 is U, and the neutral point terminal 92 is
The symbol for this is O.

[0004] The disk winding 100 includes several dozen disk coils 11.
~19, and these disc coils 11~19
is formed by stacking conductors 2 in the radial direction and winding them in a spiral shape, and the disc coil 11 has an end conductor 111 on the outer diameter side, an end conductor 113 on the inner diameter side, and these ends on the right side of the figure. It consists of a middle conductor 112 between the lower conductors and an end conductor 111.
A reinforcing insulator 31 is attached to the middle conductor 112 of winding numbers 2 and 3, and a cooling duct 5 is provided between the middle conductors 112 of winding numbers 2 and 3, through which insulating oil as a refrigerant flows from bottom to top.
Although the outer diameters are different, the disc coils 12, 13, 14 and the disc coils located further below (not shown) are the same, and the disc coils 18, 19 on the side closer to the neutral point terminal 96 are the same. Reinforcement insulation is not installed. Reinforcement insulator 31-3
The number of disk coils to which 4 is attached is about one-fourth of the number of disk coils in the disk winding 100.

An oil gap 41 whose dimensions are maintained by a spacing piece (not shown) is provided between the disc coils 11 and 12, and an oil gap 42 is provided between the disc coils 12 and 13. Even the disc coils 18 and 19 near the point terminal 96 have similar configurations. The oil gap 41 serves as a cooling duct for cooling the adjacent disc coils 11 and 12.
The purpose is to ensure dielectric strength to withstand the voltage induced between the oil gaps 42, 43, and 49, and the oil gaps between other disc coils (not shown).

As is well known, the windings of a transformer connected to a power system and operated are required to have dielectric strength against lightning surges. When a lightning surge invades, the disk winding 100
In a winding with a large number of turns, the potential distribution within the winding at the head of a lightning surge wave becomes extremely unbalanced. Disc coil 1 closest to the line terminal 91, which is the terminal through which lightning surges enter
The voltage generated between 1 and 12 may have an unbalanced distribution that is several tens of times larger than an even distribution that is proportional to the number of turns. Since the magnification of the voltage generated between the disc coils 11 and 12 is larger the closer to the line terminal 91, as shown in the figure, in the disc coils 11 to 14 at the top of the figure, each of the inner diameter side and the outer diameter side Reinforcement insulators 31, 32, 33, and 34 each having an L-shaped cross section are attached to the conductor 2 at the end of the conductor 2. On the other hand, in the figure, only two of the disc coils 18 and 19 are shown, and the disc coils on the neutral point terminal 96 side are not provided with reinforcing insulators.

[0007] The conductor 2 is numbered sequentially from 1 according to the winding order from the line terminal 91, but in this figure, the disc coils 11 to 19 are each shown as having a winding number of 4 turns. There is. As mentioned above, several hundred MV
Even if the voltage of the winding of the large capacity transformer A is extremely high, such as 154 kV, the current will be quite large, so
Since the required cross-sectional area of the conductor is large, a so-called transposed conductor is often used, in which a plurality of rectangular conductive wires with a small cross section are bundled and insulated all at once.

The largest voltage generated between the disc coils 11 and 12 is the end conductor 111 with winding number 1 and the end conductor 121 with winding number 8, and the end conductor near the line terminal 91 Since the electric field concentrates more strongly at the lower corner of 111, reinforcing insulator 31 is used to improve the dielectric strength of this part.
is attached to surround this corner. Therefore, the shape of the spacing piece (not shown) is such that the part where the reinforcing insulating material 31 protrudes downward is cut out, and the dimension of the oil gap 41 in the vertical direction in the figure is constant except for the part where the reinforcing insulating material 31 is located. Therefore, the thickness is constant and the pieces are spaced apart. The same applies to the oil gaps 42, 43 and the oil gap further below (not shown). Since no reinforcing insulation is attached to the disc coils 18 and 19, the thickness of the spacer piece forming the oil gap 49 is constant. The number of disk coils to which reinforcing insulators are attached is approximately one fourth of the number of disk coils constituting the disk winding 100.

Since the generated voltage is large in the oil gaps 41, 42, and 43, reinforcing insulators 31 to 34 are installed and the size of the oil gaps is also increased to improve insulation strength. Therefore, the oil gap at the center of the disk winding 100 (not shown) has a small size. In addition, the disk winding 100
In order to reduce the unbalance of the electromagnetic force by aligning the magnetic center of the
The dimension of the oil gap near 6 is the same as the oil gap 41 near the line terminal 91 so as to be vertically symmetrical. An unbalance in the voltage generated due to the application of an impact voltage also occurs in the oil gap 49 near the neutral point terminal 96, but it attenuates while the impact voltage propagates from the line terminal 91 toward the neutral point terminal 96. Therefore, there is a relationship that the dielectric strength does not need to be as high as the oil gap near the line terminal 91.

The maximum value of the voltage difference generated between the end conductors 111 and 121 is calculated by the following equation. Note that the symbol √ represents the square root of the following (). ΔV=V・√(C/K) ‥‥‥‥‥‥‥‥‥‥‥‥
‥‥‥‥‥‥‥‥‥‥(1) Here, ΔV; voltage difference peak value V between the disk coils; applied voltage peak value C; ground capacitance K of the disk coils 11 and 12
; Series capacitance between disc coils 11 and 12

The ground capacitance C is approximately determined by the insulation distance between the disc winding 100 and other windings or iron cores, etc.
The series capacitance K is approximately inversely proportional to the axial dimension of the oil gap 41. Therefore, for example, if the dimensions of the oil gap 41 are increased in order to increase its dielectric strength, the series capacitance K will decrease, and from equation (1), the generated voltage ΔV will increase. The characteristic is that the dielectric strength does not improve as much as it does. The reason why the reinforcing insulator 31 is attached is to improve the dielectric strength of the oil gap 41 without reducing the series capacitance K.

0012

[Problem to be Solved by the Invention] Disc coil 11 when an impact voltage is applied to line terminal 91 of disc winding 100
The peak value of the voltage difference between the conductors and 12 is approximately proportional to the difference in the number of turns. The end conductors 113 and 123 are shown as being connected by a line in the figure, but in reality they are connected by a line.
There is a voltage difference corresponding to the turn of the end conductors 111 and 121.
There is a voltage difference of 7 turns. Therefore, the voltage difference between the conductors between the disc coils 11 and 12 is largest between the end conductors 111 and 121, which are the end conductors on the outer diameter side. Therefore, since there is the highest possibility of dielectric breakdown between these end conductors 111 and 121, the reinforcing insulator 31
is attached to the end conductor 111. End conductor 121
The end conductor 111 has no reinforcing insulation attached to it.
This is because the electric field is concentrated at the corners of this conductor due to the high voltage.

The dimensions of the oil gap 41 are therefore determined by the voltage difference between the aforementioned end conductors 111 and 121;
The insulation dimensions are larger than necessary for voltage differences between other conductors. As a result, the winding physique of the disc winding 100 becomes large, and there is a problem that the space factor, which is the ratio of the total cross-sectional area of the conductors through which current can flow, to the cross-sectional area of the disc winding 100 becomes small.

An object of the present invention is to provide a disk winding that maintains dielectric strength and has a large space factor.

[0015]

[Means for Solving the Problems] In order to solve the above-mentioned problems, according to the present invention, a plurality of disc coils formed by radially overlapping and wound a plurality of turns of insulated conductors are oil-oiled. In disc windings, which are stacked in the axial direction with gaps in between, the conductors at the outer or inner radial ends of adjacent disc coils are alternately electrically connected. The conductors at at least one radial end on the inner diameter side and the outer diameter side of the plurality of disc coils on the line terminal side pulled out from one of the axial ends of the disc winding are connected to each other at this end. The radial end conductors on both sides of the disc coil shall be arranged axially apart from adjacent disc coils that are not connected to each other. Or, only the end conductor connected to the end conductor of the disc coil adjacent to the line terminal side is arranged at a position separated from the end conductor in the axial direction. The reinforcing insulator and other conductors of a disc coil to which an L-shaped cross-sectional reinforcing insulator is attached shall be in contact with a common surface of the oil gap, and the end portion to which the reinforcing insulator is attached. A reinforcing insulator with an L-shaped cross section is attached to the corner of the conductor adjacent to the end conductor on the same side as the end conductor, and reinforcing insulation is also attached to the conductor adjacent to the end conductor to which the reinforcing insulator is attached. The disc coil according to claim 4, wherein a reinforcing disc coil group consisting of a plurality of disc coils according to claim 5, each having a material attached thereto, is arranged on the line terminal side, and a reinforcing insulator is attached only to the end conductor. A reinforcing disk coil group consisting of a plurality of reinforcing disk coils is then placed.

[0016]

[Operation] In the structure of the present invention, at least one radial end on the inner diameter side and the outer diameter side of the plurality of disc coils on the line terminal side drawn out from one axial end of the disc winding. By placing the conductors axially apart from adjacent disc coils that are not connected to each other at this end, insulation strength between the end conductors of adjacent disc coils with the largest voltage difference is ensured. If the dimensions are made as follows, the dimensions between other conductors can be shortened. Therefore, the oil gap size between these two adjacent disc coils becomes smaller, increasing the series capacitance and improving the non-uniformity of the potential distribution when an impact voltage is applied. The voltage difference between the end conductors is reduced. Therefore, it becomes possible to further shorten the oil gap size between the disc coils. In the same way, the dimensions between other disc coils are also shortened, so the space factor of the disc winding is improved.

Further, by arranging the end conductors on both sides of the disc coil at positions separated from each other in the axial direction, it is possible to reduce the deviation in the axial position between the end conductors and other conductors.

Alternatively, an oil gap between adjacent disc coils can be secured by arranging only the end conductors connected to the end conductors of the disc coils adjacent to the line terminal side at positions separated from each other in the axial direction. The shape of the spacer piece becomes simple.

[0019] Furthermore, in a disc coil in which a reinforcing insulator having an L-shaped cross section is attached to the end side corner of the end conductor, this reinforcing insulator and another conductor are in contact with a common surface of the spacing piece. By arranging them in this way, the shape of the spacing piece for ensuring the oil gap becomes simple.

Furthermore, by attaching a reinforcing insulator having an L-shaped cross section to the corner of the conductor adjacent to the end conductor on which the reinforcing insulator is attached, on the same side as the end conductor, an electric field can be created at the corner of this conductor. This can compensate for the decrease in dielectric strength caused by the concentration of

In addition, a reinforcing disc coil group consisting of a plurality of the above-mentioned disc coils with reinforcing insulators attached to the conductor adjacent to the end conductor with reinforcing insulators is arranged on the line terminal side, By next placing a reinforcing disc coil group consisting of a plurality of disc coils with reinforcing insulators attached only to the conductors, it is possible to generate a It has an insulated configuration.

[0022]

EXAMPLES The present invention will be explained below based on examples. FIG. 1 shows a disk winding 100A showing a first embodiment of the present invention.
FIG. 6 is a schematic cross-sectional view of the same component as in FIG. In this figure, the surface of the reinforcing insulator 31 on the oil gap 41A side is the end conductor 113 of the winding number 4 of the coil 11A, and the end conductor 113 of the winding number 2 and 3 of the coil 11A.
The surface of the middle conductor 112 is aligned with the surface of the middle conductor 112. From the viewpoint of dielectric strength, the insulation distance between the end conductor 111 and the end conductor 121 is not larger than in the case of FIG. This means that the oil gap 41A is smaller than the oil gap 41 in FIG. 5 by at least the thickness of the reinforcing insulator 31.

In the same manner, the end conductor 123 to which the reinforcing insulator 32 is attached, the end conductor 131 to which the reinforcing insulator 33 is attached, and the end conductor 143 to which the reinforcing insulator 34 is attached are also the same. . Although the distance between the end conductors 113 and 123 is reduced by twice the thickness of the reinforcing insulators 31 and 32, the voltage difference between these conductors is small, so this does not become a factor in reducing the dielectric strength. End conductors 121 and 131
, 133 and 143 are also similar.

The oil gap on the side near the neutral point terminal 96 is 49A.
As mentioned above, in order to align the magnetic center, the oil gap 41A is
Since the dimensions of the oil gap 49A are the same, the dimensions of the oil gap 49A are also reduced.

As mentioned above, the axial position of the conductor 2 at the end is moved toward the line terminal 91 by an amount equivalent to the thickness of the reinforcing insulator 31 to provide an interval (not shown) to ensure the oil gap 41A. This is because there is an advantage that the shape of the piece becomes simple. Since the end conductor 121 protrudes upward, the number of man-hours required for manufacturing the spacing piece for the oil gap 41A is approximately the same as that for the spacing piece for the oil gap 41 in FIG. The amount of axial deviation between the end conductor 111 and the middle conductor 112 or end conductor 113 may not be made to match the thickness of the reinforcing insulator 31, but may be made smaller or larger, for example.

When the dimensions of the oil gap including the oil gap 41A are reduced, the series capacitance K mentioned above increases, and the voltage difference ΔV between the end conductors 111 and 112 decreases from equation (1). For example, if the conventional oil gap 41A has a dimension of 10 mm and the reinforcing insulator 31 has a thickness of 2 mm, the capacitance K between the adjacent disc coils 11 and 12 is approximately 20% since it is roughly proportional to the oil gap dimension. As a result, the voltage difference ΔV decreases by about 10% from equation (1). Therefore, the dielectric strength of the disk winding 100A against the impact voltage is relatively improved by 10%. Therefore, it becomes possible to increase the space factor by further reducing the size of the oil gap 41A in order to maintain the same dielectric strength. As mentioned above, the oil gap 41A also serves as a cooling duct, so the dimensions necessary for cooling are the minimum dimensions that can be taken, and even if it is allowed for insulation purposes, it cannot be made smaller than this minimum dimension. It is also possible to increase the cooling effect by reducing the insulation thickness.

FIG. 2 is a schematic cross-sectional view of a disk winding 100B showing a second embodiment of the present invention, and the same components as those in FIG. 1 are given the same reference numerals and detailed explanations will be omitted. This figure differs from FIG. 1 in that the end conductor 121 is also placed at a position moved downward in the axial direction to ensure a distance from the end conductor 111, and the movement dimension of the end conductor 121 is Since the size of the oil gap 41B can be reduced by that amount, the space factor can be further improved than in the case of FIG. The movement dimension of the end conductor 121 is the same as that of the reinforcing insulator 31.
There is no need to be particular about the thickness dimension. However, in this embodiment, the spacing pieces for the oil gap 41B are in three stages, so the manufacturing man-hours are larger than for the spacing pieces for the oil gaps 41 and 41A in the cases of FIGS. 1 and 5.

FIG. 3 is a schematic cross-sectional view of a disk winding 100C showing a third embodiment of the present invention, and illustrations of not only the central portion but also the disk coil near the neutral point are omitted. . The difference between this figure and FIGS. 1 and 2 is that a reinforcing insulator 35 is also attached to the end adjacent conductor 114, which is the conductor with winding number 2 next to the end conductor 111 to which the reinforcing insulator 31 is attached. It is a point.

If the end conductor 111 is placed in a position moved upward from the end adjacent conductor 114, the lower right corner of the conductor 114 will protrude and the electric field will become more concentrated, which may become a weak point in terms of dielectric strength. be. In order to eliminate such weak points, a reinforcing insulator 35 is attached. This reinforcing insulator 35 is normally thinner than the reinforcing insulator 31. Therefore, the shape of the spacing piece can be simplified as in FIG. 1 by making the surfaces of the reinforcing insulator 31, the reinforcing insulator 35, and the middle conductor 112 on the oil gap 41C side coincide with each other as shown in the figure. Of course, it is not a matter of making the surfaces match.

FIG. 4 is a schematic cross-sectional view of a disc winding 100D showing a fourth embodiment of the present invention, and shows a reinforcing disc coil group 110, which is the disc coil group closest to the line terminal 91. A disk coil group consisting of the disk coils 11C and 12C shown in FIG. 3 is used, and the next disk coil group 111 is a disk coil group consisting of the disk coils 11A and 12A shown in FIG. Disc coil 18D, 1
This is a configuration in which a group of 9D disk coils 120 are connected.

Generally, the disc winding 100C shown in FIG. 3 is used when the voltage difference between adjacent disc coils is larger than the disc winding 100A shown in FIG. 1 or the disc winding 100B shown in FIG. It is. For example, if the disc winding 100A or 100B is used for a disc winding with a rated voltage of 154 kV, the disc winding 100C
is used for a rated voltage of 275kV. Therefore, the disk coil group connected next to the disk coil group 110 in FIG. It can be said that connecting the coil groups 120 is rational in terms of insulation configuration. Note that the selection of the disc windings having these different configurations is made based on comprehensive judgment at the time of designing the disc winding.

[0032]

Effects of the Invention As described above, the present invention allows the conductor at the radial end of at least one of the inner diameter side and the outer diameter side of the plurality of disc coils on the line terminal side of the disc winding to be connected to this end. By arranging it at a position axially distant from adjacent disc coils that are not connected to each other at the end, the dimensions are such that the insulation strength between the end conductors with the largest voltage difference between these adjacent disc coils is ensured. Moreover, since the dimensions between other conductors can be shortened, the oil gap between the disc coils becomes smaller, the series capacitance increases, and the non-uniformity of the potential distribution with respect to the shock voltage is improved. The voltage difference between the end conductors of the disc coil is reduced. Therefore, it becomes possible to further shorten the oil gap size between the disc coils. In the same way, the dimensions between other disc coils can be shortened, resulting in the effect of improving the space factor of the disc winding. In addition, to take advantage of the reduction in voltage difference, reducing the thickness of the conductor's insulation coating instead of reducing the oil gap improves the cooling effect of the conductor, so the temperature rise of the disc winding can be kept the same as the conventional method. In order to achieve this, it is possible to increase the current density and reduce the amount of conductor material used.

As the space factor of the disc winding improves, the size of the disc winding decreases less than before, so if the width dimension, which is the radial dimension of the disc winding, is reduced, this disc winding can be reduced. Not only the winding but also the radius of the high-voltage winding placed on the outside has become smaller, reducing the amount of conductor material, making it possible to reduce the amount of iron core and insulating oil used and the dimensions of the tank that houses them.
Due to these various ripple effects, it is possible to reduce the cost of large-capacity transformers by using the disk winding according to the present invention.

Furthermore, by arranging the end conductors on both sides of the disc coil at positions separated from each other in the axial direction, it is possible to reduce the deviation in the axial position between the end conductors and other conductors.

Alternatively, an oil gap between adjacent disc coils can be secured by arranging only the end conductors connected to the end conductors of the disc coils adjacent to the line terminal side at positions separated in the axial direction. The shape of the spacer piece becomes simple, and the number of man-hours required for manufacturing the spacer piece is reduced, resulting in cost reduction.

[0036] Further, in a disc coil in which a reinforcing insulator having an L-shaped cross section is attached to the end side corner of the end conductor, this reinforcing insulator and another conductor are in contact with a common surface of the spacing piece. By arranging them in this manner, the shape of the spacing piece for ensuring the oil gap becomes simple, and the same effect as described above can be obtained.

Furthermore, by attaching a reinforcing insulator with an L-shaped cross section to the corner of the conductor adjacent to the end conductor on which the reinforcing insulator is attached, on the same side as the end conductor, an electric field can be generated at the corner of this conductor. It can compensate for the decrease in dielectric strength caused by concentration.

Further, a reinforcing disc coil group consisting of a plurality of the above-mentioned disc coils with reinforcing insulators attached to the conductor adjacent to the end conductor with reinforcing insulators is arranged on the line terminal side, By next placing a reinforcing disc coil group consisting of a plurality of disc coils with reinforcing insulators attached only to the conductors, it is possible to generate a This provides the effect of an insulating configuration.

[Brief explanation of the drawing]

[Fig. 1] A schematic cross-sectional view of a disc winding wire showing a first embodiment of the present invention.

[Fig. 2] A schematic cross-sectional view of a disc winding showing a second embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of a disk winding showing a third embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a disk winding showing a fourth embodiment of the present invention.

[Figure 5] A schematic cross-sectional view of a conventional disk winding

[Explanation of symbols]

100 Disc winding 2 Conductor 11 Disc coil 111 End conductor 112 Middle conductor 113 End conductor 12 Disc coil 121 End conductor 122 Middle conductor 123 End conductor 13 Disc coil 131 End conductor 132 Middle conductor 133 End conductor 14 Disc coil 141 End conductor 142 Middle conductor 143 End conductor 18 Disc coil 19 Disc coil 31 Reinforcement insulation 32 Reinforcement insulation 33 Reinforcement insulation 34 Reinforcement insulation 41 Oil gap 42 Oil gap 43 Oil gap 49 Oil gap 5 Cooling duct 91 Line terminal 96 Neutral point terminal 92 Covered insulation 93 Electrode 94 Static plate 95 Connection lead 100A Disc winding 11A Disc coil 12A disc coil 13A Disc coil 14A Disc coil 41A Oil gap 42A Oil gap 43A Oil gap 49A Oil gap 100B Disc winding 11B Disc coil 12B Disc coil 13B Disc coil 14B Disc coil 41B Oil gap 42B Oil gap 43B Oil gap 100C disk winding 11C Disc coil 114 End adjacent conductor 12C Disc coil 124 End adjacent conductor 13C Disc coil 134 End adjacent conductor 14C Disc coil 144 End adjacent conductor 41C Oil gap 42C Oil gap 43C Oil gap 100D Disc winding 110 Reinforcement disc coil group 111 Reinforcement disc coil group 120 Disc coil group 18D Disc coil 19D Disc coil 35 Reinforcement insulation 36 Reinforcement insulation 37 Reinforcement insulation 38 Reinforcement insulation

Claims (6)

[Claims] Claim 1: A plurality of disc coils each having an insulating coated conductor stacked in the radial direction and wound in multiple turns are stacked in the axial direction with an oil gap in between, and adjacent disc coils are stacked in the axial direction with an oil gap in between. In a disc winding in which conductors at the radial ends on the outer diameter side or the inner diameter side of the coil are electrically connected alternately, the line terminal side drawn out from one of the axial ends of this disc winding The conductor at the radial end of at least one of the inner diameter side and the outer diameter side of the plurality of disc coils is arranged at a position separated in the axial direction from adjacent disc coils that are not connected to each other at this end. A disc winding wire characterized by the following characteristics: 2. The disk winding according to claim 1, wherein the radial end conductors on both sides of the disk coil are arranged at positions separated from each other in the axial direction. 3. The disc winding according to claim 1, wherein only the end conductor connected to the end conductor of the disc coil adjacent to the line terminal side is arranged at a position separated from the end conductor in the axial direction. line. [Claim 4] A disc coil in which a reinforcing insulator having an L-shaped cross section is attached to a corner of an end of an end conductor, the reinforcing insulator and another conductor are in contact with a common surface of an oil gap. 4. The disc winding according to claim 1, 2 or 3, characterized in that: 5. A reinforcing insulator having an L-shaped cross section is attached to a corner of the conductor adjacent to the end conductor to which the reinforcing insulator is attached, on the same side as the end conductor. disk winding. 6. A reinforcing disc coil group consisting of a plurality of disc coils according to claim 5, wherein a reinforcing insulator is also attached to the conductor adjacent to the end conductor to which the reinforcing insulator is attached, is arranged on the line terminal side. A disc winding characterized in that a reinforcing disc coil group consisting of a plurality of disc coils according to claim 4 is disposed next to the reinforcing disc coil group, wherein a reinforcing insulator is attached only to the end conductor.