JP2002033219A - Gas insulating transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas insulating transformer having its improved cooling efficiency. SOLUTION: A gas insulating transformer is constituted in a structure that an inside winding 30 and an outside winding 35 are arranged in the form of a concentric circle to a core 20. Insulating cylinders 32A and 32B are respectively arranged inside and outside of the winding 30. Insulating cylinders 37A and 37B are respectively arranged inside and outside of the winding 35. Cooling gas is circulated on the peripheries of the windings 30 and 35. An insulating structure 32B is located between the cylinders 32B and 37A and is inserted between the lower end parts of the cylinders 32B and 37A. The structure 70 has a cavity in its interior.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a gas-insulated transformer.

[0002]

2. Description of the Related Art In recent years, transformers installed in cities have tended to increase in capacity due to an increase in demand for electric power in urban areas. In addition, construction of underground substations is increasing due to installation space restrictions, and the demand for non-combustible transformers is increasing.
As a transformer using such a nonflammable insulating cooling medium, an SF ₆ gas insulating transformer is known.

[0003] Here, since SF ₆ gas has a small heat capacity compared with the liquid coolant, the gas insulated transformer of a large capacity, in order to increase the cooling efficiency, SF ₆ gas using a circulating blower, etc. inside the transformer Is forcibly flown to cool a plurality of windings which are heating elements. In a conventional gas insulated transformer, a plurality of insulating cylinders are arranged between the plurality of windings. In order to efficiently cool the plurality of windings, which are heating elements, with gas, a flat ring-shaped insulating plate is arranged at the lower end of the plurality of insulating cylinders, and the cooling gas is mainly provided around the windings. Is flowing.

[0004]

However, in recent years,
The demand for miniaturization of gas-insulated transformers is increasing. Then, the present inventors reexamined the cooling efficiency of the conventional gas-insulated transformer. For that purpose, a full-scale winding model was manufactured, and as a result of measuring the upper and lower pressure differences of the winding, at the lower ends of the plurality of insulating cylinders, despite the fact that a flat ring-shaped insulating plate was arranged, Between these insulating tubes,
It was found that cooling gas was flowing. The reason is,
Since insulating paper or ring-shaped insulating plate is made of press-formed insulating paper, it expands and contracts due to moisture absorption and drying, and the shape of the insulating tube and ring-shaped insulating plate changes. It has been found that a gap is formed between the ring and the ring-shaped insulating plate, and that the cooling gas flows through the gap. As a result, it has been found that there is a problem that the cooling efficiency by the cooling gas is reduced.

It is an object of the present invention to provide a gas-insulated transformer having improved cooling efficiency.

[0006]

(1) In order to achieve the above-mentioned object, the present invention provides a plurality of windings arranged concentrically with respect to an iron core, and a plurality of windings arranged between the plurality of windings. A plurality of insulating cylinders, wherein the insulating structure has a cavity therein while being inserted between the plurality of insulating cylinders in the gas insulating transformer for flowing a cooling gas around the plurality of windings. It is provided with. With this configuration, it is possible to prevent unnecessary cooling gas from flowing between the insulating cylinders,
The cooling efficiency can be improved.

(2) In the above (1), preferably,
The insulating structure includes a corrugated insulating material and an insulating tape wound around the corrugated insulating material.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of a gas-insulated transformer according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a longitudinal sectional view showing the configuration of the gas insulated transformer according to the present embodiment, FIG. 2 is a sectional view taken along the line PP ′ of FIG. 1, and FIG. 3 is a gas insulated transformer according to the present embodiment. It is a perspective view of the insulating structure used for.

FIG. 1 shows a cross-sectional structure of a gas-insulated transformer according to the present embodiment. The actual shape of the winding, the insulating cylinder, and the like is a shape that is axially symmetric with respect to the central axis QQ. The structure above the dashed-dotted line RR is similar to the structure below the dashed-dotted line RR, and is not shown.

As shown in FIG. 1, a leg iron core 20 is disposed in the tank 10 at the center thereof.
An inner winding 30 and an outer winding 35 are wound around the outer periphery of the leg core 20. As shown in FIG. 2, the inner winding 30 and the outer winding 35 are arranged concentrically with respect to the leg iron core 20.

[0011] As shown in FIG.
A disk-shaped ring 42 is arranged. Disc-shaped rings 43 and 44 are arranged on the ring 42. On the rings 43 and 44, block-shaped tops 50 and 52 are arranged at equal intervals in the circumferential direction. Top 50, 52
Disc-shaped rings 45 and 46 are arranged on the top. On the rings 45, 46, block-shaped tops 54, 56 are arranged at equal intervals in the circumferential direction. Top 5
Disc-shaped rings 47, 48 are arranged on 4, 56. Between the rings 43 and 45, between the rings 44 and 46, between the rings 45 and 47, and between the rings 46 and 48, block-shaped tops 50,
Since it is supported by 52, 54, 56, a gap is formed, and a cooling gas (SF ₆ gas) flowing in the direction of arrow A from the gas inlet can flow between these rings. Rings 42, 43, 44, 45, 46,
47 and 48 are made of an insulating material obtained by press-molding insulating paper. Also, the frames 50, 52, 54, 56
Is also made of an insulating material.

As shown in FIG. 1, the inner winding 30 and the outer winding 35 are arranged on a ring 48. An insulating cylinder 32A is arranged on the inner peripheral side of the inner winding 30, and an insulating cylinder 32B is arranged on the outer peripheral side of the inner winding 30.
An insulating cylinder 37A is arranged on the inner peripheral side of the outer winding 35, and an insulating cylinder 37B is arranged on the outer peripheral side of the outer winding 35. As shown in FIG.
B, 37A and 37B are the inner winding 30 and the outer winding 35
Are arranged concentrically with respect to. A gas partition plate 49 is provided between the outer periphery of the insulating cylinder 37B and the tank 10, so that the cooling gas flowing in the direction of arrow A from the gas inlet does not flow to the outer peripheral side of the insulating cylinder 37B. ing. The insulating cylinders 32A, 32B, 37A, 37B and the gas partition plate 49 are formed by press-molding insulating paper. Further, gas guides 33 and 38 are provided between the coils constituting the windings 30 and 35, and the gas is flown in a zigzag manner in the windings so that the windings are uniformly cooled. That is, the cooling gas flows in the direction of arrow A from the inlet of the tank 10 by the circulating blower, and cools the windings by following the route as indicated by the solid arrow.

As shown in FIG. 2, a top 60 made of an insulating material is disposed between the insulating tube 32A and the inner winding 30. A cooling gas is provided between the insulating tube 32A and the inner winding 30. Form a gap that can be circulated. Also, the insulating tube 32
A frame 6 made of an insulating material is provided between B and the inner winding 30.
2 are formed, and a gap through which the cooling gas can flow is formed between the insulating tube 32 </ b> B and the inner winding 30. Further, a top 64 made of an insulating material is arranged between the insulating tube 37A and the outer winding 35, and forms a gap through which the cooling gas can flow between the insulating tube 37A and the outer winding 35. ing. A top 66 made of an insulating material is arranged between the insulating tube 37B and the outer winding 35, and forms a gap through which the cooling gas can flow between the insulating tube 37B and the outer winding 35. ing.

The lower end of the insulating cylinder 32A is in contact with the upper surface of the ring 43 so that the cooling gas does not flow into the inner peripheral side of the insulating cylinder 32A. Insulation tube 32B,
The lower end of 37A is in contact with the upper surface of ring 48,
The cooling gas is configured not to flow between the outer peripheral side of the insulating cylinder 32B and the inner peripheral side of the insulating cylinder 37A. However, here, the radius R1 of the outer diameter of the outer winding 35 is 5
Since the height H1 of the outer winding 35 is as large as about 1000 to 2000 mm, the insulating tube 32B is also a large-sized structure. On the other hand, since the insulating tube 32B is formed by press-molding insulating paper, it expands and contracts due to moisture absorption and drying, and the shape of the insulating tube and the ring-shaped insulating plate changes. It was found that a gap was formed between the insulating plates 48, and that the cooling gas flowed through the gap.

Therefore, in the present embodiment, between the insulating cylinder 32B located on the outer peripheral side of the inner winding 30 and the insulating cylinder 37A located on the inner peripheral side of the outer winding 35, and at the lower end thereof, Assuming that a gap is formed between the insulating tube 32B and the ring-shaped insulating plate 48 by inserting the insulating structure 70, the insulating tube 32B and the insulating tube 37A are formed through the gap.
During this time, the cooling gas is prevented from flowing.

However, in the case of a gas-insulated transformer, if an insulator is inserted into the entire lower end of the insulating cylinders 32B and 37A, the ratio of the permittivity of the gas to the insulator is large. Since an insulator is inserted into the space, the electric field at the ends of the windings increases. If the electric field at the end of the winding becomes high, the insulation performance of the transformer is threatened, and there is a possibility that insulation breakdown will occur. When the dielectric constant of gas is 1,
The dielectric constant of insulating paper used as an insulator is, for example, 3.4.
In this case, the electric field at the ends of the windings is higher than when no insulator is inserted. Therefore, in order to increase the dielectric strength, it is necessary to increase the insulation size.

Therefore, in the present embodiment, the insulating structure 70 as shown in FIG. 3 is inserted into the lower end between the insulating tube 32B and the insulating tube 37A. As shown in FIG. 3, the insulating structure 70 of the present embodiment is formed in a box shape by a corrugated insulating paper 72 and an insulating tape 74 wound around the insulating paper 72. According to this structure, since the same action as being blocked by the insulator in the center axis direction of the winding and the insulating cylinder is prevented, unnecessary flow that does not contribute to cooling of the heating element flowing between the insulating cylinders is prevented. can do.

On the other hand, considering the longitudinal cross section of the inner winding 30 and the outer winding 35, the insulating space between the two windings is not completely filled with the insulating material regardless of the cross section in the circumferential direction. is there. That is, a certain gas space is secured between the two windings, and it is possible to suppress an increase in the electric field at the ends of the windings.

As a result, by inserting the insulating structure, the flow of the cooling gas flowing between the insulating cylinder 32B and the insulating cylinder 37A can be interrupted, and the inner winding 3 to be cooled originally can be blocked.
Since the cooling gas can flow only around the zero and the outer winding 35, the cooling efficiency can be improved. As a result, the size of the gas-insulated transformer itself and the cooling device can be reduced.

Further, when the flow path of the cooling gas is improved, by using an insulating structure having a cavity therein as in the present embodiment, the dielectric constant of the entire insulating structure is reduced, and the end of the winding is reduced. , Etc., can be suppressed, and insulation reliability can be improved.

In place of the insulating structure having a cavity inside as shown in FIG. 3, a material having a lower dielectric constant than the insulating cylinder, for example, a resin-made polymer compound board (dielectric constant: 2.
4) can also be used. Further, in the above example, the two-winding transformer composed of the inner winding and the outer winding has been described, but the present embodiment is similarly applied to a three-winding transformer, a four-winding transformer, and the like. Is applicable.

As described above, according to the present embodiment, useless flow that does not contribute to cooling of the heating element can be prevented, and cooling efficiency can be improved. Further, since the equivalent permittivity of the space between the windings is low, the expansion of the insulation size can be minimized, and the reliability of insulation can be improved.

[0023]

According to the present invention, the cooling efficiency of the gas insulated transformer can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a configuration of a gas-insulated transformer according to one embodiment of the present invention.

FIG. 2 is a sectional view taken along the line P-P 'of FIG.

FIG. 3 is a perspective view of an insulating structure used in a gas insulating transformer according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Tank 20 ... Iron core 30 ... Inner winding 32A, 32B, 37A, 37B ... Insulating cylinder 33, 38 ... Gas guide 35 ... Outer winding 40 ... Clamp 42, ..., 48 ... Insulating ring 49 ... Gas partition plate 50 , 52, 54, 56 ... insulation frame 70 ... insulation structure 72 ... corrugated insulation 74 ... insulation tape

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Noriyuki Hayashi 7-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture F-term in the Electric Power and Electric Development Laboratory, Hitachi, Ltd. 5E044 CA02 CB05 5E050 HA06

Claims (2)

[Claims] A plurality of windings arranged concentrically with respect to an iron core and a plurality of insulating cylinders arranged between the plurality of windings; A gas insulating transformer for flowing a cooling gas, comprising: an insulating structure inserted between the plurality of insulating cylinders and having a cavity therein. 2. The gas-insulated transformer according to claim 1, wherein the insulating structure comprises a corrugated insulating material and an insulating tape wound around the corrugated insulating material. Gas-insulated transformer.