JPH0624992Y2 - Disk winding of oil-filled induction - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to an insulating structure of a disk winding in an oil-filled transformer such as a high-voltage, large-capacity oil-filled transformer or oil-filled reactor, especially a flat ring shape. The present invention relates to an insulation reinforced structure of a corner of a section coil.

[Conventional technology]

FIG. 3 is a cross-sectional view showing the main part of the disc winding.
Are wound and disc windings 2 holding the main insulation distance L ₁ to the outer periphery of the outer side winding 52 is wound on the main insulation distance L ₂ of the holding disc winding 2 and coaxially on the outer periphery To be dressed. Disk winding 2
Is a laminated body of a plurality of section coils 4A, 4B, 4C, etc., which are formed by winding a plurality of conductors 3 each having a rectangular cross section insulated by an electric insulating paper in a radial direction and being wound on each other in a flat plate shape. A cooling oil passage 5 having a gap g also serving as insulation between the coils is held therebetween, and a crossover 6 for electrically connecting the section coils to each other
Depending on the connection method, the conductor 3 in the figure is given a serial number to indicate the turn number through which the current flowing from the terminal 7 flows, so that the arrangement of the conductors through which the load current flows is not uniform. Line 2 is formed. By making the disk winding 2 a lightning-proof type, a voltage for a plurality of turns is applied between adjacent turns of each section coil, and the terminal 7 of the disk winding 2 is provided with a steep waveform lightning surge. When a voltage intrudes, the electrostatic capacitance between the turns is charged and the lightning surge current that flows increases, so that the voltage sharing of the section coils 4A, 4B close to the terminal 7 is significantly greater than that of the section coil far from the terminal 7. It is constructed so that it will not be expensive.

In the disk winding configured as described above, the potential difference between the outermost turns of the section coils 4A and 4B (turn numbers 1 and 20) is the largest, and the corner portions (outer edges) A ₁ and A ₂ are opposed to each other. The electric field concentration of becomes large. Also,
There is a potential difference of 9 turns between the innermost turns of the section coils 4A and 4B, and the opposite corners (inner edges) B ₁ , B
Electric field concentration to ₂ increases next to _A 1, _{A 2.} In addition, 1 is assigned to the outermost turns of the section coils 4B and 4C.
There is no potential difference for the turn, and therefore the outer edges C ₁ , C ₂
The electric field concentration on is small.

As described above, in the disc winding, the difference in potential (difference in the number of turns) between adjacent section coils occurs, and a high electric field portion is generated near the corner of the conductor with a large potential difference. When there is an oil gap, the withstand voltage strength is lower and the permittivity is smaller than that of oil-impregnated paper insulation coating, so the oil gap is more likely to be concentrated based on the principle of electrostatic capacitance division. Becomes a weak point, and the withstand voltage strength of the disk winding decreases.

As a measure for eliminating such weak points of insulation and improving the withstand voltage strength of the disk winding, conventionally, as shown in FIG. 4, an electric insulating paper such as kraft paper tape is wound around the rectangular conductor 3A. Insulation coating 11 is added to the innermost circumference turn or outermost circumference turn 14 (hereinafter referred to as end conductor) of the section coil 4 formed by winding the conductor 3 applied with the insulation coating 3B (hatching is omitted in the figure). By strengthening the insulation of the end conductors 14 and separating the oil gaps 12A, 12B existing outside the corners of the additional insulating coating 11 from the corners of the rectangular conductor 3B as much as possible, the oil gaps 12A, 12B
It is known to be configured to reduce the electric field of. Further, as shown in FIG. 5, an insulating ring 21 having an L-shaped cross section covering one corner of the end conductor 14 of the section coil 4 is provided, and an oil gap, which is a weak point of insulation, is kept away from the outside. , Which is configured to strengthen the insulation of the corners A ₁ , A _{2 and the} like in FIG.

[Problems to be solved by the device]

In the conventional structure in which the end conductor 14 is provided with the additional insulating coating 11, the additional insulating coating 11 is often formed by manually winding an insulating paper tape, which not only increases the number of steps but also tightly taps the additional insulating coating. Since it is difficult to form 11, it is difficult to obtain a reliable reinforced insulation effect. On the other hand, the insulating ring 2 having an L-shaped cross section
In the conventional structure in which the corner portion of the section coil 4 is covered with 1, a thick press board is used to keep the oil gap away.
Since it is necessary to shape it into a letter shape and the curved portion of the bending angle 21A inside the insulating ring 21 is larger than the radius of curvature of the bending angle of the outer circumference of the end conductor 14, the inner peripheral surface or the outer peripheral surface of the end conductor 14 is It is unavoidable that an oil gap 22 is generated between the insulating ring 21 and the insulating ring 21. The insulating ring 21 made of an oil-impregnated pressboard has a dielectric constant of 4 or more, while the oil gap 22 has a small dielectric constant of about 2.2. Has a problem that the electric field reaches about twice as much as that in the insulating ring 21, and the oil gap 22 becomes a weak point to cause partial discharge in the oil. There is a drawback that the purpose of can not be achieved.

An object of the present invention is to obtain an insulating structure that effectively uses the insulating ring by improving the configuration and arrangement of the insulating ring.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, according to the present invention, the section coils that are adjacent to each other and are made of a laminate of a plurality of flat plate ring-shaped section coils in which a conductor covered with an insulation is wound plural times in a flat plate ring shape. And a pair of insulating rings having L-shaped cross sections which are opposite to each other and cover the inner peripheral side and the outer peripheral side of the section coil or one of them, and the pair of insulating rings are electrically connected to each other. It is assumed that the press coils have different thicknesses, and that a pair of insulating rings overlap each other and a thin insulating ring is in contact with the section coil, and is attached to the section coil so as to be in contact with the outside of the section coil and covered with a thick insulating ring.

[Action]

The outer circumference and the inner circumference of the section coil are covered with a pair of insulating rings having mutually opposite L-shaped cross sections having different thicknesses from each other, and the pair of insulating rings overlap each other. By placing a thin insulating ring in contact with the coil on the surface or the inner peripheral surface and by arranging a thick insulating ring in contact with the outer surface of the coil, the oil gap between the conventional thick insulating ring and the inner and outer peripheral surfaces of the coil is reduced. Insulating oil that is largely replaced by a thin insulating ring and greatly reduces the volume of the wedge-shaped oil gap that remains in contact with the edges of the thin insulating ring, increasing the withstand voltage strength in inverse proportion to the volume. It is possible to improve the withstand voltage performance of the end of the section coil by utilizing the characteristics of. In addition, the edge of the thin insulating ring contacts the wedge-shaped oil gap, so that the action of alleviating the electric field in the oil gap is created based on the principle of electrostatic capacitance partial pressure, further improving the withstand voltage performance of the oil gap. It becomes possible. In addition, the corners of a coil covered with a thick insulating ring should be placed between coil sections with a high electric field concentration, and the corners of a coil covered with a thin insulating ring should be placed between coil sections with a low electric field concentration. As a result, an insulation reinforced structure corresponding to the degree of electric field concentration can be obtained.

〔Example〕

 The present invention will be described below based on embodiments.

FIG. 1 is an enlarged cross-sectional view of an essential part showing an apparatus according to an embodiment of the present invention, and the same parts as those in the prior art are designated by the same reference numerals and detailed description thereof will be omitted. In the figure, the section coil 4 is provided with a thin insulating ring 31 made of a press board having an L-shaped cross section, which is bent in an L-shape at the corner of the end conductor 14, and is adhered to the surface of the section coil 4 with an adhesive or the like. And the insulation at one corner is strengthened. Further, at the other corner of the end conductor 14, the thick L is bent in an L shape opposite to the insulating ring 31.
A thick insulating ring 21 having a V-shaped cross section is mounted so as to hold the overlapping margin l and cover one surface of the thin insulating ring 31. As a result, most of the oil gap 22 produced in the conventional structure already described with reference to FIG. 5 has been replaced by a thin insulating ring 31 with a stacking margin l, a thick insulating ring 21 and an insulated coated end conductor 14. And an elongated wedge-shaped oil gap 32 left along the edge of the thin insulating ring 31 is left, and the volume of the wedge-shaped oil gap 32 is significantly larger than that of the oil gap 22 in the conventional structure. It is reduced.

In general, it has been revealed in recent years that the dielectric breakdown voltage of insulating oil decreases depending on the number of impurities such as conductive fine particles contained in the insulating oil. Since it has a role of reducing the number of impurities such as, the withstand voltage performance of the wedge-shaped oil gap 32 having a reduced volume is improved as compared with that of the oil gap 22 in the conventional structure. On the other hand, as shown in the potential distribution diagram in the vicinity of the wedge-shaped oil gap 32, as shown in FIG. 2, the oil gap is replaced by the thin insulating ring 31 having the overlap margin l, so that the equipotential lines 100 in the insulating ring 31 are separated from each other. And the electric field in this portion is relaxed, and the electric field relaxation effect is such that the electric wires 100 extending into the wedge-shaped oil gap 32 through the edge 31A of the insulating ring are widened so as to relax the electric field. Extend to Therefore,
Compared with the conventional structure in which the thin insulating ring 31 does not exist, the action of improving the withstand voltage strength of the oil gap obtained by reducing the volume of the oil gap and the action of improving the withstand voltage performance of the oil gap obtained by relaxing the electric field are synergistic. Of the wedge-shaped oil gap 32, the withstand voltage performance of the wedge-shaped oil gap 32 is significantly improved, and thus the weak point of insulation, which has been a problem in the conventional structure, is eliminated.

Further, the corner portion of the section coil 4 covered with the thick insulating ring 21 has a higher electric field at the corner portion A ₁ or A ₂ , and the corner portion covered with the thinner insulating ring 31 has a higher electric field concentration than A ₁ , A ₂ . By arranging the arrangement so that it is located at a low position, for example, B ₁ , B ₂ or C ₁ , C ₂ , it is possible to obtain a disk winding in which the corner insulation is reinforced in response to the electric field concentration. A lightning-proof disk winding with high insulation reliability against surge voltage can be obtained. Further, since the insulating ring can be easily attached to a required place during the winding assembling work, a labor saving effect can be expected as compared with the conventional structure having the additional insulating coating.

[Effect of device]

As described above, the present invention covers both or one of the outer circumference side and the inner circumference side of the section coil with a pair of insulating rings which are formed in L-shapes opposite to each other and have different thicknesses, and a thin insulation is provided at a portion where the both overlap. The ring was arranged so as to be in contact with the coil surface. As a result, the insulation is strengthened by closely covering one corner with a thin insulating ring, and the oil gap, which was a problem in the conventional structure using one insulating ring, is Is greatly reduced, and the withstand voltage performance of the wedge-shaped oil gap is greatly improved by the synergistic effect of the improvement effect of the withstand voltage strength of the insulating oil and the relaxation effect of the electric field based on this, so it was covered with a thick insulating ring. The coil corners are highly insulated and strengthened.
Therefore, it is possible to provide the disk winding of the oil-filled electric device in which insulation is reinforced corresponding to the degree of electric field concentration at the corners of the section coil, by using the insulating ring that facilitates labor saving.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment structure of the present invention, FIG. 2 is a potential distribution diagram in the embodiment structure, FIG. 3 is a sectional view of an essential part showing an example of a disk winding, and FIG. FIG. 5 and FIG. 5 are cross-sectional views of a main part showing a conventional structure. 2 ... Disc winding, 3 ... Insulating coated conductor, 3A ... Rectangular conductor, 3B ... Insulating coating, 4, 4A, 4B, 4C ... Section coil, 14 ... End conductor (outermost circumference turn, innermost circumference turn) ), 11 ... additional insulation coating, 21 ... thick insulation ring, 2
2 ... Oil gap, 31 ... Thin insulating ring, 32 ... Wedge-shaped oil gap, 100 ... Equipotential line, l ... Overlap margin, A ₁ ,
A ₂ , B ₁ , B ₂ ... Corners where the electric field is concentrated.

Claims (1)

[Scope of utility model registration request] 1. A structure comprising a laminate of a plurality of flat-plate ring-shaped section coils obtained by winding a plurality of insulation-coated conductors in a flat-plate ring shape, wherein the adjacent section coils are electrically conductively connected to each other. A pair of insulating rings having mutually opposite L-shaped cross-sections covering the inner peripheral side and the outer peripheral side of the section coil, or any one of the inner peripheral side and the outer peripheral side, the pair of insulating rings being press boards having different thicknesses, A disk winding of an oil-filled induction machine, characterized in that a thin insulating ring is in contact with the section coil, and a thick insulating ring is in contact with the outer side of the section coil so that a pair of insulating rings overlap each other. line.