JPH0521238A - Oil filled electrical equipment - Google Patents

Abstract

PURPOSE:To acquire stable insulation performance by removing a fine oil gap effectively. CONSTITUTION:Non-fibrous and porous soft insulating sheets 3a to 3h are arranged by pressure contact at least one place of a part which is positioned in insulation oil and where a fine oil gap is formed such as between a disc coil 6b of a high tension winding 12 and a spacer 5 between coils, and between a pressing bolt 14 of an upper winding supporting fitting 13 and an insulating supporting base 4b, the fine oil gap is removed and formation of an oil gap which linearly passes from front to rear is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-filled electric device such as an oil-filled transformer or a reactor, and particularly to an oil having an insulating structure suitable for insulating a portion where a wedge-shaped oil gear is formed in insulating oil. Regarding electrical appliances.

[0002]

2. Description of the Related Art In windings of high-voltage, large-capacity oil-filled transformers known as oil-filled electrical equipment, a large amount of paper made of high-quality wood pulp is used as an insulating material in addition to mineral oil. For example, kraft paper or crepe paper is used as an insulating coating for windings and lead wires, and various spacers for securing cooling oil passages in the windings, insulators that make up the main insulation, and to support the windings. BACKGROUND ART Press boards made by strongly compressing paper have been used as materials for supporting insulators arranged above and below windings, insulating cylinders for forming a lead wire barrier, spacers, and arms for supporting lead wires. That is, the insulation of the transformer winding is a composite insulation of these insulating papers and mineral oil used as insulating oil. By the way, comparing the dielectric constant of oil-impregnated paper obtained by impregnating these insulating papers with that of mineral oil, the relative dielectric constant of mineral oil is about 2.2, while the dielectric constant of oil-impregnated paper is There are about 3.5 to 4.7, and the oil-impregnated paper is about 1.5 to 2 times larger. Therefore, the electric field burden of the insulating structure in which these are arranged in series is relaxed in the oil-impregnated paper, and the portion is wrinkled by the mineral oil and the electric field is concentrated on the mineral oil. Moreover, since the insulating strength of mineral oil is much smaller than that of oil-impregnated paper, the insulating strength of mineral oil ultimately determines the insulating strength of the composite insulation system of the winding.

Such electric field concentration on the mineral oil increases as the proportion of the size of the oil-impregnated paper in the insulating dimension increases. For example, in a winding consisting of a disk coil, a cooling duct is secured. Concentration is large at the oil gear where the linear spacers and inter-coil spacers are arranged. Above all, the electric field of the wedge-shaped fine oil gear at the portion where the disc coil contacts the linear spacer or the inter-coil spacer is likely to be concentrated due to the geometrical electric field concentration due to the angular disc coil. Therefore, it is known that this fine oil gear often becomes a weak point in insulation and causes dielectric breakdown. Similarly, the electric field concentration of the fine oil gear between the coil and the spacer for the cooling duct is large even in the multi-cylindrical winding consisting of the cylindrical coil and the winding of the outer iron transformer consisting of the pancake coil. It has become. In the outer circumference of the winding, the electric field concentration increases due to the fine oil gear between the high-voltage lead wire and the support arm pulled out from the winding and the fine oil gear between the lead wire and the spacer for the lead wire barrier. In the vicinity of the winding support bracket, the electric field is concentrated due to the fine oil gear between the corner of the winding support bracket and the winding support insulator, which is a weak point in insulation.
As described above, the fine oil gears formed in the insulating oil in a wedge shape are weak points in the insulation.

In order to eliminate such weak points and improve the dielectric strength, for example, in the winding, JP-A-62-1
As described in Japanese Patent Publication No. 47710, by applying a material having a dielectric constant of 1.3 times or less that of mineral oil to the insulating coating of the disk coil, the inter-coil spacer and the linear spacer, What prevents concentration of an electric field in a fine oil gear, and as described in Japanese Utility Model Application Laid-Open No. 59-93116, a soft material made of cotton fiber as a raw material between the disk coil and the inter-coil spacer and the linear spacer. Or, a semi-rigid paper is placed and compressed to eliminate fine oil gears, which is a weak point, and further, it is disclosed in Japanese Patent Laid-Open No.
As described in Japanese Patent Publication No. 7-83010, a porous or fibrous elastic porous body is applied to the corners of the disk coil, and an insulating cover is further covered on the disk coil to apparently cover the disk coil with insulation. For example, the thickening reduces the electric field of the fine oil gear near the corners of the disk coil. For the high voltage lead wire support, see
As described in Japanese Patent Publication No. 7-78624, there is one in which a fine oil gap is eliminated by disposing a felt-like insulating paper between the supporting arm and the lead wire. Similarly, as for the barrier portion of the high-voltage lead wire, as described in Japanese Patent Laid-Open No. 63-60509, the outermost layer of coating insulation, the spacer, and the insulating cylinder are made of a fine mixed material of low dielectric constant plastic and pulp. There is one that prevents the electric field from being concentrated in the oil gear. Further, regarding the vicinity of the winding support metal fitting, Japanese Patent Laid-Open No. 48-54
As described in Japanese Laid-Open Patent Publication No. 434, there is one in which an electric field shield is arranged on the edge of the metal fitting to reduce the electric field of the fine oil gear.

[0005]

As described above, in the oil-filled electrical equipment, various proposals have been made to prevent electric field concentration in the fine oil gear, and particularly, JP-A-59-93.
No. 116, Japanese Utility Model Laid-Open No. 57-78624 and Japanese Patent Laid-Open No. 57-83010 can apparently remove fine oil gears, but all of them use a fibrous material. Felt and soft paper have small fiber density and sparse fiber parts, and the gap between the fibers is wiped out at that part, forming an oil gear tape that runs from the front surface to the back surface in a straight line or a path close to a straight line. Actually, when seeing through felt or soft paper, it may be observed with the naked eye that relatively large holes are formed from the front surface to the back surface. In such a case, insulation breakdown is likely to occur through the oil gear at a low voltage, and stable insulation performance cannot be obtained.

It is an object of the present invention to provide an oil-filled electric device having a stable insulating performance by efficiently removing fine oil gears.

[0007]

In order to achieve the above object, the present invention is characterized in that a soft insulating sheet made of a non-fibrous and porous material is arranged at a portion where a fine oil gear is formed. .

[0008]

In the oil-filled electric device according to the present invention, the soft insulating sheet as described above is arranged in the portion where the fine oil gear is formed. Since the soft insulating sheet is a porous body, it is very soft, for example, a coil. If it is placed between the spacer and the spacer, it will be crushed by the compressive force when winding the coil at the time of manufacturing the winding and the tightening load from the upper part of the winding after manufacturing the winding, and the part where no pressure is applied at that time will keep the shape as it is. To maintain it, the fine oil gap is filled along the contour of the coil, and this soft insulating sheet is made of a non-fibrous porous material, so the inside is finely divided into a film or layer, An oil gear gap that linearly communicates from the front side to the back side of the seat is not formed, and thus stable dielectric strength can be obtained. Further, this soft insulating sheet is simply cut into an appropriate size and shape and inserted into the fine oil gear, and the number of manufacturing steps hardly increases.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view showing an oil-filled transformer as an oil-filled electrical device according to an embodiment of the present invention. A soft insulating sheet 3a made of a non-fiber and porous insulator is laid on the lower support metal fitting 2 attached to the lower part of the iron core 1, and an insulating support base 4a is placed on the soft insulating sheet 3a, and a coil is placed on the insulating support base 4a. The spacers 5a and the disk coils 6a are alternately stacked to form the low voltage winding 7
Is formed. Inter-coil spacer 5 of this low-voltage winding 7
A soft insulating sheet 3b similar to the above-described soft insulating sheet 3a is inserted between a and the disk coil 6a, and this soft insulating sheet 3b has a size slightly protruding from the width of the inter-coil spacer 5a. I am trying. An electrostatic shield 8a is placed on the uppermost part of the low-voltage winding 7, and the soft insulating sheet 3b described above is also inserted between the electrostatic shield 8a and the inter-coil spacer 5a. Further, the same soft insulating sheet 3c as that described above is applied to the outside of the low-voltage winding 7, a linear spacer 9 is applied to the outside thereof, and insulating paper is wound on the outside thereof to form an insulating cylinder 10. The same linear spacers 9 and insulating cylinders 10 are alternately arranged in the main insulation 1
Make up one. The soft insulating sheet 3c at this time
Has a width slightly larger than the linear spacer 9.

On the outermost linear spacer 9 of the main insulation 11, a soft insulating sheet 3d is placed on the linear spacer 9, and on the outer side thereof,
The electric wire is wound while being tightened to form the disk coil 6b, and the disk coil 6b and the inter-coil spacer 5b are formed.
Are alternately stacked to form the high-voltage winding 12. A soft insulating sheet 3e similar to the above soft insulating sheet 3b is inserted between the disk coil 6b and the inter-coil spacer 5b, and the width of the soft insulating sheet 3e slightly extends beyond the inter-coil spacer 5b. It has a size. An electrostatic shield 8b is provided at the top of the high voltage winding 12,
The soft insulating sheet 3e is also inserted between the electrostatic shield 8b and the inter-coil spacer 5b.

The insulating support base 4b is placed on top of the low-voltage and high-voltage windings 7 and 12 thus formed, and then the upper support metal fitting 13 having the push bolt 14 mounted thereon is mounted on the iron core 1. At this time, the soft insulating sheet 3f is inserted between the push bolt 14 and the insulating support base 4b.
Then, a load is applied to the insulating support 4b by the push bolt 14 to tighten the low-voltage and high-voltage windings 7 and 12 to form a winding body.

From the upper end of the high voltage winding 12 to the high voltage lead wire 15
And connect it to the high pressure bushing 16. At that time,
A support arm 17 having a hole into which the high voltage lead wire 15 is inserted is taken out from the upper support metal fitting 13, and the high voltage lead wire 15 is housed in this hole to support the middle of the lead wire 15. Further, in a portion where the insulation distance from the periphery of the high voltage lead wire 15 is small, an insulating paper is wound around the spacer 18 to dispose a lead wire barrier 19. Between the support arm 17 and the insulating coating 20 of the high voltage lead wire 15, the soft insulating sheet 3
g, and a soft insulating sheet 3h wider than the spacer 18 is also inserted between the spacer 18 and the insulating coating 20 of the high voltage lead wire 15. All of these are stored in a tank 21 filled with mineral oil 22 and a transformer winding 23 of a disk winding is used.
Is configured.

FIG. 2 is an enlarged view of a portion of the high voltage winding 12 of the transformer winding 23 according to the present invention, where the disk coil 6b corresponds to the linear spacer 9 and the inter-coil spacer 5b. The disk coil 6b is a conductor 25 with an insulating coating 24.
The soft insulating sheets 3e, 3d are crushed by the tightening pressure and the tightening load from the upper part when the coil is wound, and the fine oil gaps that adhere to each other and become weak points on the insulation are removed. Similarly, the soft insulating sheets 3b and 3c of the low-voltage winding 7 are also crushed and brought into close contact with each other to eliminate the fine oil gap. Compared to the conventional structure, the soft insulating sheet is simply cut into a predetermined size and inserted, and there is almost no increase in the number of steps. In addition, the portion where the soft insulating sheet is inserted is originally the portion where the spacer or the like is in contact, and there is no oil flow. Therefore, even if the soft insulating sheet is inserted, the cooling performance hardly changes.

FIG. 5 is an enlarged view of a portion where the electrostatic shield 8b of the high voltage winding 12 of the transformer winding 23 of the present invention corresponds to the linear spacer 9 and the inter-coil spacer 5b. After the high-voltage winding 12 is wound around the electrostatic shield 8b,
It is inserted from the top and then tightened from the top. Due to the pressure and tightening load due to this insertion, the soft insulating sheet 3
The e and 3d are crushed, and the fine oil gap, which is a weak point in insulation, between the electrostatic shield 8b and the linear spacer 9 and the inter-coil spacer 5b is removed. At that time, as a new work, the insulating sheets 3e and 3d are simply cut and inserted, and the man-hours hardly increase.

FIG. 3 is an enlarged view of the vicinity of the push bolt 14 having the highest electric field in the upper support fitting 13 shown in FIG. The soft insulating sheet 3f is crushed by the tightening load of the push bolt 14,
The fine oil gear gap between the insulating support base 4b and the insulating support base 4b is removed.

FIG. 4 is an enlarged view of the vicinity of the corner of the lower support metal fitting 2 shown in FIG. 1 where the electric field is highest. The soft insulating sheet 3a is crushed by the load from the upper part, and the fine oil gear gap between the edge portion of the lower support fitting 2 and the insulating support base 4a is removed.

FIG. 6 is an enlarged view of the supporting portion of the high voltage lead wire 15 shown in FIG. The high-voltage lead wire 15 is put in the holes formed in the opposing portions of the support arms 17a and 17b, which are divided in half, and is sandwiched and fixed by the insulating bolt 26. The soft insulating sheet 3g is crushed by the tightening pressure of the insulating bolt 26, and the fine oil gap between the high-voltage lead wire 15 and the supporting arms 17a and 17b is buried and removed.

FIG. 7 is a cross-sectional view of the barrier insulating portion of the high voltage lead wire 15 shown in FIG. When the insulating paper is wound to form the lead wire barrier 19, the soft insulating sheet 3h is crushed by the clamping pressure of the insulating paper, and the fine oil gear gap between the spacer 18 and the insulating coating 20 of the high voltage lead wire 15 is filled. It has been crushed and removed.

According to the oil-filled transformer described above, it is possible to remove the fine oil gap of each part, which is a weak point in insulation, without increasing the number of manufacturing steps and impairing the cooling performance. The electric field concentration in the fine oil gap differs depending on the insulation structure, but the electric field in the normal part is roughly 1.
It is about 5 to 2 times. Therefore, the electric field in each part of the transformer winding 23 is 1 / th that of the prior art due to the elimination of the fine oil gear.
It is relaxed to about 1.5 to 1/2. As a result, the insulation strength of the transformer winding 23 is improved by about 1.5 to 2 times compared with the conventional one, and if the working voltage is the same, the insulation distance is 1 / 1.5 to 1/2 of the conventional one. It can be shortened to the extent.

By the way, the inter-coil spacers 5a, 5b,
Linear spacer 9, upper and lower insulating support bases 4a and 4b, insulating cylinder 10, supporting arms 17a and 17b, and lead wire barrier 1
As the material of the spacer 18 of No. 9, a press board which has been widely used from the past is adopted, while as the material of the soft insulating sheets 3a to 3h, a non-fibrous porous material obtained by stretching or foaming various plastic materials. The body. FIG. 8 and FIG. 9 show examples of the dielectric breakdown voltage when these non-fibrous porous body and fibrous porous body were used, which were experimentally investigated.

FIG. 8 is a perspective view showing the model 27 used in the experiment. It is assumed that two conductors 25 provided with an insulating coating 24 are arranged to face each other, and an inter-coil spacer 5b is sandwiched between them by a soft insulating sheet 3e, and the high-voltage winding 12 shown in FIG. The insulating structure between the coils 6b was simulated. The model 27 was immersed in an oil tank, a lightning impulse voltage was applied to the upper conductor 25, the lower conductor 25 was grounded, and the breakdown voltage was examined. When a lightning impulse voltage is applied to the upper conductor 25 while increasing the voltage by one shot from a lower voltage, the fine oil formed between the insulating coating 24 and the inter-coil spacer 5b when the soft insulating sheet 3e is not inserted. Partial discharge of lightning impulse occurs from the gear,
The streamer reaches the surface of the insulating coating 24 of the ground-side electric wire, and finally penetrates the insulating coating 24 to cause a dielectric breakdown between the coils along a path as shown in A of FIG. On the other hand, when the soft insulating sheet 3e is inserted, the dielectric breakdown from such fine oil gears decreases, and the dielectric breakdown often occurs along the path indicated by B near the end face of the inter-coil spacer 5b. In particular, when a non-fibrous soft insulating sheet 3e is used, the dielectric breakdown as shown in B almost occurs.

FIG. 9 shows breakdown voltages for various soft insulating sheets. The breakdown voltage when the non-fibrous soft insulating sheet 3e is inserted is the breakdown voltage when the soft insulating sheet 3e is not inserted. By comparison, the average value is improved by about 1.65 times, and the minimum value is also improved by the same degree. On the other hand, the breakdown voltage when the fibrous soft insulating sheet 3e is inserted is
The average value is an improvement of about 1.2 times, the effect is smaller than that when a non-fibrous material is inserted, and the lowest value is not much different from the breakdown voltage when the soft insulating sheet 3e is not inserted. This is because there is a sparse part of the fiber because the density of the fibers is small, as you can see that holes are drilled to the back side in some places when you see through the soft fibrous insulating sheet 3e, and there is a sparse part of the fiber, Of the soft insulating sheet 3e may be sewn into the gap between the front and back of the soft insulating sheet 3e in a substantially linear manner, and the dielectric strength of such an oil gear is such that the insulation strength of the portion where fibers are densely packed is high. It is smaller than the proof stress, and therefore the breakdown voltage becomes low.

On the other hand, in the case of a non-fibrous material, it is made into a porous body by foaming or stretching, and in the case of foaming, a large number of pore membranes overlap intricately. Since the pieces of material that are finely divided by drawing also overlap in a complicated manner, there are no holes that lead from the front surface to the back surface in a path that is close to a straight line as in the case of fibrous material. Therefore, the breakdown voltage is high. Therefore, a non-fibrous porous body is suitable as the material of the soft insulating sheet 3e. Regarding the dielectric constant of the non-fibrous porous material, electric field analysis shows that 1.
When the amount is 3 times or less, even if it is inserted, it does not affect the surrounding electric field so much. Therefore, a low dielectric constant of 1.3 times or less that of mineral oil is preferable. As the non-fibrous porous material, for example, polytetrafluoroethylene stretched Goretex, Microtex, Matsushishiru (all are trade names), and various rubbers such as silicone rubber, nitrile rubber, and neoprene rubber are foamed. Silicone sponge,
Nitrile sponge, neoprene sponge, and various general foam foam materials, such as polyurethane foam, polyethylene foam, polystyrene foam, and polymethylpentene foams, which are not common yet, are preferable. Porous bodies of tetrafluoroethylene, polyethylene, polyurethane, polystyrene and polymethylpentene have a relative dielectric constant of 2.1 to 2.
It is about 7, which is preferable because it is 1.3 times or less the relative dielectric constant of mineral oil. In particular, Goretex, Microtex, and Matsushiyushiru (all trade names) made by stretching polytetrafluoroethylene have almost the same dielectric constant as mineral oil, so even if they are inserted, they have almost no effect on the surrounding electric field and the diameter of the pores. It is very suitable because it has a uniform distribution and a small distribution of dielectric strength, has no independent pores, has a good oil impregnation property, and has a good oil resistance at high temperatures.

The proportion of voids in the soft insulating sheets 3a to 3h, that is, the porosity, is required as follows from the viewpoint of the mechanical strength of the winding. Since the soft insulating sheets 3a to 3h are soft, they hardly help in maintaining the mechanical strength of the winding. Therefore, from a mechanical point of view, the soft insulating sheets 3a to 3h
The smaller the percentage, the better. In that respect, if the soft insulating sheets 3a to 3h are crushed to less than 1/2 of the original thickness due to the pressing and tightening pressures during the winding production, a fine oil gear tape can be efficiently used without using a too thick one. It can be buried, and the mechanical strength of the winding is hardly reduced, and it is in good condition.
By the way, with such a relatively small force, the material itself of the soft insulating sheets 3a to 3h is hardly compressed, and such a shape change is possible only when the holes in the soft insulating sheets 3a to 3h are crushed. is there. Therefore, the porosity of the soft insulating sheets 3a to 3h may be 50% or more, but according to the insulation test result by the model 27 shown in FIG. 8, when the porosity exceeds 90%, the porosity rapidly increases. Breakdown voltage decreases. This is because the ratio of the material is drastically reduced and most of the material becomes oil. Therefore, the porosity of the final soft insulating sheets 3a to 3h is preferably 50% or more and 90% or less. .

The thickness of the soft insulating sheets 3a to 3h is determined by the electric field distribution of the applicable section. In FIG. 10, as an example, the thickness t of the soft insulating sheet 3e is changed between the disk coils 6b. The electric field of the fine oil gap near the corners of the disk coil 6b is shown. Soft insulation sheet 3
The compression ratio of e is 1/2, and the electric field is 5
The thickness t is divided by the electric field of the oil gear portion in the oil gap portion not in contact with b, and the thickness t is divided by the curvature radius R of the corner portion of the disk coil 6b to be normalized.

As can be seen from the figure, the soft insulating sheet 3e
When the thickness t / R is approximately 1, the electric field of the fine oil gear cup becomes approximately equal to the electric field of the normal oil gear cup. That is,
The optimum thickness of the soft insulating sheet 3e between the disc coils 6b is preferably about the same as the radius of curvature of the corners of the disc coil 6b. Since the corners have a radius of curvature of about 1 to 3 mm, the thickness of the soft insulating sheet 3e is about 1 to 3 mm. It should be noted that even if the thickness is further increased, dielectric breakdown occurs in the oil gear of a normal portion, the breakdown voltage does not increase, and there is no effect. On the other hand, even when the thickness is thin, the effect is lost when the thickness becomes less than a certain level. This is because the surface of the insulating coating 24 has irregularities, and the insulating coating 24 usually has many tape windings. In that case, the irregularities of the surface of the insulating coating 24 are at least about 0.2 mm due to the irregularities of the tape overlap. At least the thickness that fills the irregularities on the surface of the insulating coating is necessary to bring out the effect even a little. Therefore, if the compression rate of the soft insulating sheet 3e is halved, the thickness of the soft insulating sheet 3e needs to be at least about 0.4 mm.

As a result of investigating a suitable thickness from the electric field distribution in other parts, it is largely different depending on the transformer, but in the lower winding support fitting 2 and the upper winding support fitting 13, 1 to 10 mm.
About 1 to 5 mm at the supporting portion of the high voltage lead wire 15,
The lead wire barrier 19 has a thickness of about 1 to 3 mm.

The pore diameters of the soft insulating sheets 3a to 3h are preferably set as follows from the viewpoint of dielectric breakdown. As described above, the streamer progresses as a precursor of dielectric breakdown, and the diameter of this streamer is about 10 μm. Therefore, if the pore diameter, that is, the diameter exceeds 10 μm, the streamer easily enters the pores, and dielectric breakdown easily occurs. Therefore, the pore diameter should basically be 10 μm or less. However, according to the experiment, the pore diameter is 10 μm
The breakdown voltage does not drop sharply as soon as it exceeds the
It has a tendency to gradually decrease, and has an effect of improving breakdown voltage up to a pore diameter of about 200 μm. This is a soft insulating sheet 3
This is because, when a to 3h are compressed and crushed, the holes are also crushed and the hole diameter becomes smaller. Therefore, the pore diameter of the soft insulating sheet used may be 200 μm or less.

It should be noted that, in addition to the above-mentioned porous body as the material of the soft insulating sheets 3a to 3h, those having a thin leaf internal structure, for example, Cornex and Nomex 411 (all are trade names) are known. Density is 0.3g / cm
^{About 3} aramid sheets can be used although there is no hole that goes straight from the front side to the back side, so the effect may be somewhat reduced, but it is possible to use a sheet with a higher density up to about 0.5 g / cm ³ from the compression rate. .

Next, another embodiment of the present invention, that is, a specific mounting structure of the soft insulating sheet will be described. FIG. 11 shows a case where the surface of the disk coil 6b is covered with the soft insulating sheet 3i. The end surface of the soft insulating sheet 3i in the winding direction is tapered, and after covering the surface of the disk coil 6b, The taper parts are overlapped and bonded so that they do not come off. In FIG. 13, the surface of the electrostatic shield 8b is covered with the soft insulating sheet 3i, and the end faces in the winding direction of the soft insulating sheet 3i are tapered to form the electrostatic shield 8b.
After covering the surface, the taper parts are overlapped and adhered so that they do not come off. FIG. 12 is a cross-sectional view of the surface of the push bolt 14 of the upper support metal fitting 13 covered with the soft insulating sheet 3j. The soft insulating sheet 3j is slightly stretched and pressed against the surface of the push bolt 14 to be peeled off by adhesion. I try not to. FIG. 14 is a cross-sectional view of the case where the surface of the lower support metal fitting 2 is covered with the soft insulating sheet 3k. As in the case of the push bolt 14 described above, the soft support insulating material sheet 3k is slightly stretched while the surface of the lower support metal fitting 2 is extended. They are pressed against each other and bonded so that they do not come off. In FIG. 15, the surface of the high voltage lead wire 15 is covered with a soft insulating sheet 3l.
Shows a perspective view when covered with a soft insulating sheet 3
The end face of 1 is tapered, and after covering the surface of the high-voltage lead wire 15, the tapered portions are overlapped and adhered so as not to be peeled off. When the surface of the high electric field portion is covered with the soft insulating sheets 3i to 3l in this manner, the manufacturing process takes a lot of time, but the soft insulating sheets 3i to 3l do not shift during winding production, and the fine oil gear tape, which is a weak point, is surely secured. Can be buried in.

16 to 18, instead of covering the high electric field portion with the soft insulating sheets 3i to 3l, the surfaces of the inter-coil spacer 5b, the linear spacer 9 and the lead wire barrier spacer 18 which are in contact with the high electric field portion are shown. The soft insulation sheet 3
The perspective view which covered with m-3p and adhered and integrated with each member so that it might not come off is shown. In this case as well, it takes a lot of manufacturing man-hours, but when the winding is manufactured, the soft insulating sheet 3m to 3p is used.
It is possible to surely fill the fine oil gap without slipping off. On the other hand, the embodiment shown in FIGS.
It is a modification of the embodiment shown in FIGS. 16 to 18 described above,
On the surface of each of the spacers 5b, 9 and 18 facing the high electric field portion,
The soft insulating sheets 3q to 3s, which are a little wider than the surface, are bonded and integrated. As a result, almost the same effect as the above case can be obtained. However, the end faces of the mechanically weak flexible insulating sheets 3q to 3s are formed by the spacers 5b, 9,
Since it protrudes from the end face of 18, care must be taken when handling it, but there is an effect of cost reduction because it is easy to manufacture. The inter-coil spacer 5b shown in FIGS.
With regard to the above, by preliminarily adhering the soft insulating sheet 3m or 3q to a long-sized spacer base material and integrating them, and punching it into a spacer shape with a punching machine, the number of molding steps can be reduced.

FIG. 22 is a perspective view showing a mounting structure when the soft insulating sheet 3t is applied to the inter-coil spacer 28 having a U-shaped cross section. A soft insulating sheet 3t, which is slightly wider than the inter-coil spacer 28, is attached to and supported on the inner surface of the inter-coil spacer 28 that contacts the disc coil 6b, whereby a U-shaped inter-coil spacer 28, which is a weak point, is formed. The fine oil gap between the disc coils 6b is filled.

FIG. 23 is a sectional view showing a mounting structure in which the soft insulating sheet 3u is applied to the spacer 29 having a corrugated cross section for the lead wire barrier. The surface of the corrugated spacer 29 facing the high voltage lead wire 15 is shown. Soft insulating sheet 3u
Are pasted together. As a result, the fine oil gap between the corrugated spacer 29 and the high voltage lead wire 15, which is a weak point, is filled.

FIG. 24 is a sectional view showing a mounting structure when the soft insulating sheet 3v is applied to the step insulating spacer 30 of the step insulating portion of the high-voltage winding 12, and it is shown in FIG. The soft insulating sheet 3v is attached to the contact surface. As a result, the weak oil gap between the step insulating spacer 30 and the disc coil 6b is filled up.

FIG. 25 is a cross-sectional view showing a mounting structure to which the present invention is applied when an electric wire is directly wound around the surface of the outermost insulating cylinder 10 of the main insulation 11 to form a winding. A soft insulating sheet 3x is attached to and supported by the surface of the insulating cylinder 10 facing the disk coil 6b so that the weak oil gap between the insulating cylinder 10 and the disk coil 6b, which is a weak point, is buried. I have to.

FIG. 26 is a perspective view showing a situation in which the high voltage winding 12 is assembled using the employment 32. When winding the electric wire 33 to form the disk coil 6b, a rectangular parallelepiped employment 32, which is slightly thicker than the inter-coil spacer 5b, is inserted between the inter-coil spacer 5b and the inter-coil spacer 5b on the same circumference. Then, after forming the disc coil 6b, the disc coil 6b is pulled out. Thereby, when forming the disk coil 6b, the soft insulating sheets 3y arranged on both surfaces of the inter-coil spacer 5b.
Since no force is applied to the soft insulating sheet 3y, the soft insulating sheet 3y will not be displaced or twisted, and the fine oil gap can be surely filled. As a material for the employment 32, a plastic having good sliding property, for example, tetrafluoroethylene is suitable.

FIG. 27 is a sectional view showing a winding end portion when a soft insulating sheet is applied to a transformer winding having multiple cylindrical windings. A soft insulating sheet 34 is wound around the outer circumference of the interlayer insulating paper 33, an electric wire 35 is wound on the soft insulating sheet 34 to form a cylindrical coil 36, and an electrostatic shield 37 is arranged above the cylindrical coil 36. The sheet 34 is sized to cover the upper end of the electrostatic shield 37. Thereafter, the spacer 38 is arranged on the outer peripheral surface of the cylindrical coil 36. At that time, the soft insulating sheet 3 is provided between the cylindrical coil 36 and the spacer 38.
9 is arranged, and the width of the soft insulating sheet 39 is made a little wider than the width of the spacer 38. An interlayer insulating paper 40 is wrapped around the spacer 38. The multi-cylindrical transformer winding 43 is constructed in such a manner that the soft insulating sheet 41 is then covered on the thus formed one, and the cylindrical coil 42 is further formed thereon. According to the transformer winding 43 having such a configuration, the soft insulating sheets 34, 39, 41 is crushed, and fine oil gaps, which are weak points between the cylindrical coils 36 and 42 and the electrostatic shield 37, the interlayer insulating papers 33 and 40, and the spacer 38, are removed.

FIG. 28 is a sectional view showing the structure of the winding when the soft insulating sheet is applied to the transformer winding of the outer iron type transformer. First, the electric wire 44 is wound in a rectangular shape to form a pancake coil 45, and the soft insulating sheet 4 is attached to the end of the pancake coil 45.
6 and cover it with an insulating cap. Next, the insulating piece 48 is arranged thereon, and the inter-coil insulating paper 49 is further arranged thereon. A spacer 50 is arranged between the center surface of the pancake coil 45 and the insulating paper 49 between the coils,
At that time, the soft insulating sheet 51 is arranged between the pancake coil 45 and the spacer 50. This soft insulating sheet 51
Is slightly larger than the spacer 50. A plurality of the thus formed ones are arranged so that their comrades form a V shape, and although not shown, a wedge is driven between the iron core and the iron core to tighten them laterally, and the supporting insulator 52 is vertically provided.
Is arranged and pressed down from above and below to form the transformer winding 53 of the outer iron transformer. According to the transformer winding 53 having such a configuration, the soft insulating sheets 46 and 51 are crushed by the tightening pressure from the lateral direction and the vertical direction, and the fine gap between the pancake coil 45, the insulating cap 47 and the spacer 50 is reduced. The oil gap can be removed.

Although the application to the oil-filled transformer winding has been described above, the present invention can be applied to other oil-filled electrical equipment. In addition, it is desirable to provide a soft insulating sheet for all fine oil gears formed in insulating oil, but prioritize the parts that are the weakest points in insulation and place the soft insulating sheet from the part with the highest priority. You may.

[0040]

As described above, according to the present invention, a soft insulating sheet made of a non-fibrous porous material is provided in pressure contact with at least one portion of a portion where a fine oil gear gap, which is a weak point in insulation, is formed. Therefore, it is possible to improve the dielectric strength by removing the fine oil gear and to obtain an oil-filled electric device having stable insulation performance.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a transformer winding shown as an oil-filled electric device according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of an essential part near the disc coil shown in FIG.

FIG. 3 is an enlarged cross-sectional view of an essential part near the upper winding support fitting shown in FIG.

FIG. 4 is an enlarged cross-sectional view of an essential part near the lower winding support fitting shown in FIG.

5 is an enlarged cross-sectional view of a main part near the electrostatic shield shown in FIG.

FIG. 6 is an enlarged perspective view of a main part of the high voltage lead wire supporting portion shown in FIG. 1.

FIG. 7 is an enlarged cross-sectional view of a main part of a lead wire barrier portion shown in FIG.

8 is a perspective view of an experimental model used to examine the insulation between the disc coils shown in FIG. 1. FIG.

9 is a breakdown voltage characteristic diagram of various soft insulating sheets according to the experimental model shown in FIG.

FIG. 10 is a characteristic diagram showing the relationship between the thickness of the soft insulating sheet and the electric field of the fine oil gap.

FIG. 11 is a cross-sectional view of a disk coil that is a main part of an oil-filled electrical device according to another embodiment of the present invention.

FIG. 12 is a sectional view of a push bolt which is a main part of an oil-filled electrical device according to another embodiment of the present invention.

FIG. 13 is a sectional view of an electrostatic shield that is a main part of an oil-filled electrical device according to another embodiment of the present invention.

FIG. 14 is a cross-sectional view of a lower support fitting which is a main part of an oil-filled electrical device according to another embodiment of the present invention.

FIG. 15 is a partial cross-sectional perspective view of a high voltage lead wire which is a main part of an oil-filled electrical device according to another embodiment of the present invention.

FIG. 16 is a perspective view of an inter-coil spacer that is a main part of an oil-filled electrical device according to another embodiment of the present invention.

FIG. 17 is a perspective view of a linear spacer that is a main part of an oil-filled electrical device according to another embodiment of the present invention.

FIG. 18 is a perspective view of a lead wire barrier spacer, which is a main part of an oil-filled electrical device according to another embodiment of the present invention.

FIG. 19 is a perspective view of an inter-coil spacer that is a main part of an oil-filled electrical device according to still another embodiment of the present invention.

FIG. 20 is a perspective view of a linear spacer which is a main part of an oil-filled electrical device according to still another embodiment of the present invention.

FIG. 21 is a perspective view of a lead wire barrier spacer, which is a main part of an oil-filled electrical device according to still another embodiment of the present invention.

FIG. 22 is a perspective view of an inter-coil spacer, which is a main part of an oil-filled electrical device according to still another embodiment of the present invention.

FIG. 23 is a sectional view of a corrugated spacer for a lead wire barrier, which is a main part of an oil-filled electrical device according to still another embodiment of the present invention.

FIG. 24 is a cross-sectional view of a stepped insulating spacer that is a main part of an oil-filled electrical device according to still another embodiment of the present invention.

FIG. 25 is a cross-sectional view of the vicinity of an insulating cylinder of main insulation, which is a main part of an oil-filled electrical device according to still another embodiment of the present invention.

FIG. 26 is a perspective view showing a situation of winding assembly which is a main part of an oil-filled electrical device according to still another embodiment of the present invention.

FIG. 27 is a cross-sectional view of a multiple cylindrical winding that is a main part of an oil-filled electrical device according to still another embodiment of the present invention.

FIG. 28 is a cross-sectional view of a transformer winding that is a main part of an oil-filled electrical device according to yet another embodiment of the present invention.

[Explanation of symbols] 1 iron core 2 Lower support bracket 3a-3y soft insulating sheet 4a, 4b insulating support base 5a, 5b Spacer between coils 6a, 6b disk coil 9 Straight spacer 10 Insulation cylinder 12 high voltage winding 13 Upper support bracket 14 Push bolt 15 High voltage lead wire 17a, 17b Support arm 18 Spacer 19 Lead wire barrier

Continued front page    (72) Inventor Hiroyuki Fujita             1-1-1 Kokubuncho, Hitachi-shi, Ibaraki Stock             Hitachi, Ltd. Kokubu factory

Claims (4)

[Claims] 1. In an oil-filled electric device obtained by immersing a winding wire in insulating oil in a tank, a non-fibrous porous material is provided in at least one part of the insulating oil where fine oil gears are formed. An oil-filled electric device, which is provided by pressing a soft insulating sheet composed of a body. 2. The oil-filled electric device according to claim 1, wherein the dielectric constant of the soft insulating sheet is 1.3 times or less the dielectric constant of the insulating oil. 3. The oil-filled electrical device according to claim 1, wherein the porosity of the soft insulating sheet is 50% or more and 90% or less. 4. The oil-filled electrical device according to claim 1, wherein the soft insulating sheet has a pore diameter of 200 μm or less.