JPS63187608A - Oil-immersed induction electric apparatus - Google Patents

Abstract

PURPOSE:To improve the dielectric strength at the end of winding where high electric field is created, by coating an L-shaped barrier faced to an insulator and an oil duct, an insulating cylinder, a straight spacer and an insulating stand on a shield ring, with a pulp fiber layer. CONSTITUTION:Several low-voltage disk coils 3 are stacked on a core leg 1 while several high-voltage disk coils 2 are stacked on the outside thereof. These coils are wound coaxially and annular shield rings L and H are arranged on the tops of the low-voltage and high-voltage disk coils 3 and 2, respectively. The shield ring L is insulation coated by winding low dielectric tape 15a formed of an insulator having a low dielectric constant on the outside of a conductive shield electrode 9a and further winding paper tape 16b formed of pulp fibers on the surface of said tape 15a, so that the electric field at the end of the low-voltage winding is weakened.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an oil-filled induction appliance.

[Conventional technology]

Generally, electric field concentration is large at the ends of oil-immersed induction appliances, such as transformer windings, and dielectric breakdown is likely to occur.

For this reason, as described in Japanese Utility Model Application Publication No. 57-80816 or No. 57-80817, a shield electrode with rounded corners is provided to alleviate the electric field. Furthermore, as described in Japanese Utility Model Application Publication No. 56-85930, an insulating angle ring is provided on the inner circumferential side of the end of the high voltage winding to prevent dielectric breakdown from the end of the high voltage winding. Stationary induction appliances have also been proposed.

[Problem that the invention seeks to solve]

However, the most important factor for dielectric breakdown at the end of the winding is the breakdown of the oil gap between the shield electrode and the insulated angle ring, and how to alleviate the electric field concentration during this time is the key to achieving high withstand voltage. This is the key. In other words, as mentioned above, one way is to round the corners of the shield electrode to alleviate the electric field, but since there are limits to the width of the a'G pressure winding and the height of the shield electrode, There is also a limit to the size of the roundness, making it difficult to expect even greater electric field relaxation. Furthermore, the oil gap between the shield electrode and the insulated angle ring is affected by the breakdown voltage drop ψ due to the smoothness of the solid insulator surface. In other words, when fibrous fuzz exists on the surface of a solid insulator, the fibers stand up in the direction of the electric field and 1
This is because it creates a locally high electric field area.

The present invention has been made in view of the above points, and it is an object of the present invention to provide an oil-immersed induction electric appliance that makes it possible to improve the dielectric strength of the winding ends where a high electric field occurs.

[Means for solving problems]

The above purpose is to install an L-shaped barrier, an insulating cylinder, a linear spacer, and an insulating stand on the shield ring facing the insulator and oil pipe.
This is achieved by covering with a fiber layer made of wood.

In other words, the shield ring placed at the end of the winding wound around the core leg covers the conductive shield electrode with a low dielectric constant insulator (low dielectric constant insulator), and the outermost layer is made of pulp fiber. +1 was achieved by covering it with paper tape. In addition, the L-shaped barrier and insulating tube arranged to surround the entire circumference of the end of the winding are made of a low dielectric constant insulator and pulp fibers are tightly attached to the surface of the low dielectric constant insulator, so that at least the above-mentioned oil gap surface has a low dielectric constant. It is constructed so that the insulator is not exposed.

The dielectric constant of pressboard, which is generally used in oil-immersed transformers, is approximately 4.7 when it is impregnated with oil.

The idea is to reduce the electric field applied to the oil gap by lowering the dielectric constant of this material, and one way to lower the dielectric constant is to mix conventional pulp fibers with low dielectric constant plastic fibers to make paper. There are applications for breathboards. This has the advantage that it has better oil impregnation properties than plastic sheets or plastic cast products, and can eliminate insulation defects such as void discharge. However, mixed paper made of plastic fibers and pulp fibers has a disadvantage in that the surface of the mixed paper becomes more fluffy because the degree of intertwining between A and 11 is poorer than that of presspod made of 100% pulp. In order to suppress this fuzz, the surface is coated with pulp fibers as described above.

[Effect]

With the above configuration, the low permittivity T1:L ratio reduces the oil gap between the winding and the insulating cylinder at the end of the winding, the L-shaped barrier and the winding, and the L-shaped barrier and the end shield. The electric field in the first oil gap can be relaxed, and since the surface of the low dielectric constant insulator is coated with a pulp fiber with good fiber entanglement, the fluff of the fibers in the oil, which becomes the first oil gap, can be reduced. can be minimized. Therefore, in the first oil gap, which is the first cause of dielectric breakdown, it is possible to reduce the dielectric constant without creating a localized high electric field portion, and the electric field can be relaxed.

〔Example〕

The present invention will be explained below based on the illustrated embodiments. An embodiment of the present invention is shown in FIGS. 1-3.

As shown in the figure, the oil-filled induction electric appliance is wound around an iron core leg 1, and has high and low voltage windings 2a formed of high and low voltage disc coils 2 and 3.

3a, shield rings L, H placed at the ends of these windings 2a, 3a and covered with an insulator.

These shield rings L, H and the winding 2a.

L arranged to form and maintain an oil passage around 3a
shaped barrier 4+4a, insulating tubes 5, 5a, linear spacer 6.
6a, and insulating stands 7, 78 on the shield ring. In the figure, 8.8a is a spacer between coils, 9 and 9a are conductive shield electrodes of shield rings L and H, 10° and 10a are insulating stands, and 11. lla is an insulating disk, and 12°13.14 is an insulating cylinder between windings. In this embodiment of the oil-immersed induction electric appliance constructed as described above, the seal 1 includes four rings L and H, an insulating material such as a low dielectric constant tape 15, 15a covering the electrically shielding poles 9 and 9a, and a surface facing each other. The L-shaped barriers 4, 4a, the insulating tubes 5.5a, the linear spacers 6.6a, and the insulating stands 7, 7a on the shield ring were covered with a pulp fiber layer.

By doing this, the dielectric strength of the winding end, which is exposed to a high electric field, is improved, and an oil-immersed induction electric appliance that has the ability to improve the dielectric strength of the winding end, which is exposed to a high electric field, is improved. Obtainable.

That is, the low-voltage disc coil 3 stacked in multiple stages on the core leg 1 and the high-voltage disc coil 2 stacked in multiple stages on the outside thereof are wound concentrically, and the upper end of the low-voltage disc coil 3 and Annular shield rings L are provided at the upper ends of the high-voltage disc coils 2, respectively.

II is located. Among these, seals 1 to ring L are provided with conductive shield electrodes 9a as shown in FIG.
A low dielectric constant tape 15a made of a low dielectric constant material and a dielectric constant material is further wrapped around the surface of the tape 15a, and a paper tape IGb made of a valve fiber is wrapped around the surface of the tape 15a for insulation. The shield ring L relieves the electric field at the end of the low voltage winding. The shield ring ■ [is a seal I attached to the upper end of the high-voltage disc coil 2.Similar to that of the ring ring, a low &t f6 >M, which causes the upper bound relaxation at the end of the high voltage winding to be IA
It is being

A winding cooling channel is maintained between the inside of the high-voltage winding 2a and the outside of the low-voltage winding 3a, and an oil gap x; 'Na one person (
Insulating tubes 5, 5a and pulp tubes 12, 13.14 are arranged between the windings and wires made of pulp wt iff:, and for the same purpose, low dielectric tubes 12, 13. L-shaped barrier 4, 4a with multiple insulating stands 10°1 in the circumferential direction
An annular insulating disk 11 held at 0a. lla is provided. In addition, in order to maintain the above-mentioned first mH formed between the L-shaped barriers 4 and 4a to a predetermined dimension, a linear spacer 6°6Q of a low dielectric constant insulator and one insulating stand 7 and 7a on the shield ring are used. is used. The L-shaped barriers 4, 4a and insulating cylinders 5, 5a made of low dielectric constant insulator are made of pulp fiber and low dielectric constant plastic till XI:
The press pod 18 is made by mixing and forming the press pod 18, and the L-shaped barrier 4° 4a is molded from this. Furthermore, these surfaces were constructed by providing a thin pulp fiber layer 17 made of pulp LMl'lf on the surface of the low dielectric constant mixed paper press pod 18, as shown in FIG. In other words, a low dielectric constant mixed paper press pod 18, which is a mixed paper made of pulp fibers and plastic fibers, is sandwiched between pulp fiber layers 17 made only of pulp fibers, and the press pod 1
Plastic and fibers were not exposed on the surface of 8.

Incidentally, as shown in FIG. 4, which shows the 5IQ results of the low dielectric constant mixed press pod 18 without the pulp fiber layer 17, many fluffs 19 stand up on the surface. This problem is caused by the difference in heat deformation temperature between pulp fibers and plastic glue, and the fact that plastic fibers are relatively straight, so they do not intertwine as well as pulp fibers do. be. FIG. 5 shows the results of examining the insulation strength using a basic model when an insulator having fluff 19 is arranged as a linear spacer or a barrier for an oil gap.

In the figure, model A is a model in which fluffy mixed paper is sandwiched between coils covered with kraft paper and impregnated with oil, and model 3 is a model without fluff. We calculated the lightning impulse breakdown voltage for these models A and B, or as shown in the figure, the breakdown voltage of model B is different from that of model A.
It was higher than that of . This is because the seven starting points of failure in Model A and Model B are both wedge-shaped oil gaps created between the coil and the linear spacer, or if fluff is present in the wedge-shaped oil gap like in Model A, the seven starting points of failure are from that position. This is because discharge occurs at a low voltage, that is, if there is fluff with a higher dielectric constant than oil in the high electric field oil gap, local electric field concentration occurs in that part, making it easy to break down. If you get rid of the fluff, you can break Model B JJ.
As is clear from the voltage characteristics, it can be effective in improving the breakdown voltage.

By the way, in a composite insulation system composed of oil and a solid insulator, if the dielectric constant of the solid insulator is large, the electric field applied to the oil will be large, and if the dielectric constant of the solid insulator is low, the electric field will be applied to the oil by that much. This electric field becomes smaller. Furthermore, since the dielectric breakdown strength of solid insulators is generally higher than that of oil, breakdown occurs from the oil part.

Therefore, reducing the dielectric constant of the solid insulator as much as possible increases the breakdown strength of the entire insulation system.

As described above, according to this embodiment, a low dielectric constant insulator (low dielectric constant tape 15°1'5a) is provided at the ends of the windings 2a and 3a, and thin paper tapes 16a and 1 made of pulp fiber are provided on the surface thereof.
Place the shield rings L and H coated with the layer 6b,
Also, L-shaped barriers 4, 4a and an insulating cylinder 5.5a arranged to form an oil passage around the shield rings L, H and the windings 2a, 3a, and a linear spacer 6.6a for holding the oil passage. Since the surface of the low dielectric constant mixed paper press pod 18 is coated with a thin pulp fiber layer 17, the surface of the insulator, which serves as an oil channel, can have less fuzz, and combined with the low dielectric constant of the insulator, the oil gap can be reduced. The breakdown voltage can be increased, and the dielectric strength of the ends of the winding where the electric field is high can be improved.

〔Effect of the invention〕

As mentioned above, the present invention improves the dielectric strength of the winding ends where a high electric field occurs, and provides an oil-immersed induction electric appliance that makes it possible to improve the dielectric strength of the winding ends where a high electric field occurs. Obtainable.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal side view of the essential parts of an oil-filled induction electric appliance according to an embodiment of the present invention, FIG. 2 is a longitudinal side view of the essential parts of a shield ring of an embodiment of the invention, and FIG. 3 is an embodiment of the same embodiment. FIG. 4 is a longitudinal cross-sectional side view showing a state in which a pulp fiber layer is provided on the surface of the low dielectric constant insulator, and FIG. 1 is a characteristic diagram showing the results of a comparative study of breakdown voltages between a model according to this embodiment and a model according to a conventional example. 1... Iron core leg, 2... High voltage disc coil, 2a...
High voltage winding, 3...Low voltage disc coil, 3a...Low voltage winding, 4゜4a...1, Shape barrier, 5, 5a...Insulating cylinder, 6, 6a...Linear spacer, 7 .7a...Insulating stand on shield ring, 9,9a...Conductive shield electrode, 15°15a...Low dielectric constant tape (insulator), 16
a. 16b...Paper tape, 17...Pulp fiber layer, 18
...Low dielectric constant mixed press pod (low dielectric constant insulator),
L, H... Shield ring. 1st Kuzu Z” 3rd figure $4ryot5 edict

Claims (1)

[Claims] 1. High- and low-voltage windings made of high- and low-voltage disc coils wound around iron core legs, and shields disposed at the ends of these windings and covered with an insulating material. An oil-filled induction electric appliance comprising a ring, an L-shaped barrier, an insulating cylinder, a linear spacer, and an insulating stand on the shield ring arranged to form and maintain an oil path around the shield ring and the winding, as described above. An oil-filled induction electric appliance characterized in that an insulator, an L-shaped barrier facing an oil channel, an insulating tube, a linear spacer, and an insulating stand on a shield ring are covered with a pulp fiber layer. 2. The oil-filled induction electric appliance according to claim 1, wherein the insulating tube is made of a low dielectric constant insulator whose at least the surface facing the winding is coated with a pulp fiber layer. 3. Claim 1, wherein the L-shaped barrier is made of a low dielectric constant insulator whose at least the surface facing the shield ring is covered with the pulp fiber layer.
Oil-filled induction electric appliances as described in . 4. The shield ring is composed of a conductive shield electrode, the low dielectric constant insulator coated on the electrode, and a paper tape made of pulsed fibers and coated on the surface of the insulator. An oil-filled induction electric appliance according to claim 1. 5. The oil-filled induction electric appliance according to claim 1, wherein the linear spacer is a low dielectric constant insulator. 6. The oil-immersed induction electric appliance according to claim 1, wherein the insulator on the shield ring is a low dielectric constant insulator.