JP6505496B2 - Gas-insulated on-load tap changer - Google Patents

Description

  Embodiments of the present invention relate to a gas-insulated on-load tap changer.

  In recent years, substations installed in central Tokyo are being shifted to the underground type in an attempt to make them compact because large-scale construction on the ground is difficult. With the transition to underground type substations, gas-insulated transformers in which an insulating gas is sealed in a sealed container are mainly used as transformers disposed in the substations. This is because gas insulation transformers are excellent in environmental performance and safety.

  Normally, the on-load tap switching device is incorporated in the transformer connected to the grid to stabilize the grid voltage, but the gas-insulated load is used in response to the transformer becoming a gas-insulated system. An hour tap changer is employed. In the gas-insulated on-load tap changer, a gas container having a sealed structure is attached to the opening of the transformer tank, and the switching switch is accommodated in the gas container. Moreover, the tap selector is arrange | positioned under the gas container, and is connected with the transformer side via the tap lead wire.

JP, 2013-247170, A

  With the increasing number of underground substations installed in central Tokyo, it is required to further miniaturize the equipment that constitutes the substation, and it is also required to compact the gas-insulated on-load tap changer. ing. Although it is essential to improve the withstand voltage characteristics in compacting the device, it is important to suppress local electric field concentration in order to realize it. In particular, in the switching switch, switching of the effective tap is performed without interrupting the circuit, so it is an issue to reduce the maximum electric field value inside the gas container that accommodates this.

  An embodiment of the present invention has been proposed to solve the above-mentioned problems, and provides a gas-insulated on-load tap switching device in which the maximum electric field value is reduced and the withstand voltage characteristic is improved. With the goal.

In order to achieve the above object, a gas-insulated on-load tap changer according to an embodiment of the present invention includes the following components (1) to (5).
(1) A gas container which forms an opening at the upper end and encloses an insulating gas inside.
(2) A head cover fitted to the opening of the gas container.
(3) A sealing member for sealing between the gas container and the head cover.
(4) A seal pressing member for pressing the seal member.
(5) An internal shield member that covers the lower end portion of the seal pressing member.

FIG. 1 is a perspective view of a first embodiment. BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows the whole structure of 1st Embodiment. The expanded sectional view of the A section of FIG. The expanded sectional view which shows the equipotential line of a comparative example with 1st Embodiment. Sectional drawing which shows the equipotential line of 1st Embodiment. The perspective view of 2nd Embodiment. The expanded sectional view of the A section of FIG. Sectional drawing which shows the equipotential line of 2nd Embodiment. The perspective view of 3rd Embodiment. The expanded sectional view of the A section of FIG. Sectional drawing which shows the equipotential line of 3rd Embodiment.

First Embodiment
A first embodiment according to the present invention will be specifically described using FIGS. 1 to 5. The first embodiment is a gas-insulated on-load tap changer and is characterized by a structure related to ground insulation. Before describing this structure, the overall configuration of the gas-insulated on-load tap changer will be described with reference to FIG.

(overall structure)
As shown in FIG. 2, in the gas-insulated on-load tap changer 2, a gas container 2 c is attached to the opening of the transformer tank 1 in which the insulating gas 3 is enclosed. The gas container 2c is formed of a cylindrical member having an opening at the upper end. The switching switch 2a is accommodated in the gas container 2c, and an insulating gas 4 for insulating and cooling the switching switch 2a is enclosed. For example, SF6 gas or the like is used as the insulating gases 3 and 4.

  Below the gas container 2c, a tap selector 2b for selecting a pair of tap positions is disposed. The tap lead wire 5 corresponding to each tap potential is drawn out from the winding of the transformer not shown, and by joining these tap lead wire 5 to the tap selector 2b, the transformer and the on-load tap changer A circuit connection with 2 is made.

(Configuration of structure related to ground insulation)
The structure relating to the ground insulation of the gas-insulated on-load tap changer will be described with reference to FIGS. 1 and 3. 1 and 3 show the vicinity of the upper end portion of the gas container 2c. A head cover 6 is fitted in the opening at the top of the gas container 2c. The head cover 6 is a member for isolating the switching switch 2 a from the transformer tank 1. The head cover 6 is formed of a metal material having a cylindrical portion extending downward, and the cylindrical portion of the head cover 6 is fitted into the opening at the top of the gas container 2c.

  A seal member 8 for sealing both of the gas container 2c and the head cover 6 is disposed, and a seal pressing ring 7 for pressing the seal member 8 is disposed on the lower end surface of the cylindrical portion of the head cover 6 There is. The seal pressing ring 7 is joined to the lower end surface of the cylindrical portion of the head cover 6 by a bolt 7a (shown in FIG. 3).

  In addition, a tube-shaped external shield member 11 having a circular cross section is horizontally attached to the outer peripheral portion of the gas container 2c along the outer periphery of the gas container 2c. The outer shield member 11 is disposed below the lower end portion of the seal pressing ring 7. The outer shield member 11 is a member which is not conducted to the head cover 6.

  An insulating cylinder 13 is coaxially disposed inside the gas container 2c. An upper shield plate 9 is fixed to an upper portion in an inner peripheral portion of the insulating cylinder 13, and a lower shield plate 10 is fixed to the lower portion with a predetermined distance from the upper shield plate 9. The upper shield plate 9 and the lower shield plate 10 are disposed parallel to each other. The upper shield plate 9 is a member for protecting the concentration of the electric field on the metal member on the upper side (ground side) of the switching switch 2a, and the lower shield plate 10 is the lower side of the switching switch 2a A member that protects the concentration of the electric field on the metal member.

(Structure of the main part)
FIG. 3 shows a cross-sectional view of a portion A in FIG. As shown in FIG. 3, a flat portion 12 is formed on the opposite surface, that is, the lower surface of the seal pressing ring 7 on the charging portion side. The flat portion 12 is disposed substantially perpendicular to the inner peripheral surface of the gas container 2c. An inner shield member 14 made of an aluminum plate material is attached to the flat portion 12 of the seal pressing ring 7. The inner shield member 14 is conducted to the head cover 6.

  The inner shield member 14 is provided with a curved surface portion 14 a having a semicircular cross section. The curved surface portion 14 a is formed to cover a part of the flat surface portion 12 of the seal pressing ring 7 and the bolt 7 a joined to the seal pressing ring 7. The curved surface portion 14 a is disposed so as to cover the flat surface portion 12 of the seal pressing ring 7 halfway. Therefore, a gap 16 is formed between the end of the curved surface portion 14a and the inner peripheral surface of the gas container 2c.

(Action and effect)
Generally, in the gas-insulated on-load tap changer 2, the part where electric field concentration is a problem in the ground insulation is near the lower end of the seal pressing ring 7. Therefore, as shown in FIG. 4, it is conceivable to directly form a curved surface portion at the end of the seal pressing ring 7. However, in this case, the distance between the curved surface portion and the inner peripheral surface of the gas container 2c is narrow, and an acute wedge-shaped gap 17 is formed. As a result, although the curved surface portion is formed, strong electric field concentration still occurs near the lower end portion of the seal pressing ring 7, and the equipotential line also remains steep.

  With respect to the above-mentioned problems, in the first embodiment, the inner shield member 14 is attached so as to cover the lower end portion of the seal pressing ring 7, and the inner shield member 14 is provided with the curved surface portion 14a. Since the inner shield member 14 is a member independent of the seal pressing ring 7, the curved surface portion 14a having a semicircular cross section can be easily provided, and the surface of the curved surface portion 14a draws a gentle curve.

  Moreover, the gap 16 is formed between the end of the curved surface portion 14a and the inner peripheral surface of the gas container 2c, and the end of the curved surface portion 14a is not in contact with the inner peripheral surface of the gas container 2c. As a result, as shown in FIG. 5, the electric field between the seal pressing ring 7 and the gas container 2c can be relaxed, the occurrence of the electric field concentration is suppressed, and the interval of the equipotential lines becomes wide.

  According to the first embodiment as described above, the maximum electric field value inside the gas container 2c can be reduced, for example, by about 23% as compared with the case where the inner shield member 14 is not provided. As a result, even if the apparatus is made compact, excellent insulation reliability can be secured, which can contribute to the improvement of the ground insulation performance. In addition, even if a mixed gas or the like having a lower insulating performance than SF6 gas is used as the insulating gas 4, the maximum electric field value inside the gas container 2c is suppressed, so the generation of the electric field concentration is assured. It is possible to prevent.

  In addition, since the inner shield member 14 is formed of an aluminum plate, the withstand voltage characteristics can be efficiently enhanced. Furthermore, in the first embodiment, since the lower end portion of the seal pressing ring 7 only forms the flat portion 12, it is not necessary to process the seal pressing ring 7 for electric field relaxation, which reduces the manufacturing cost and is economical It is possible to enhance sex.

Second Embodiment
A second embodiment according to the present invention will be specifically described with reference to FIGS. The basic configuration of the second embodiment is the same as that of the first embodiment, and the same reference numerals are given to the same parts, and the description will be omitted.

(Constitution)
In the second embodiment, as shown in FIGS. 7 and 8, an inner shield member 14 made of an aluminum plate material is attached to the flat portion 12 of the seal pressing ring 7. A second outer shield member 15 is disposed at a position above the outer shield member 11 and below the seal pressing member 7 on the outer peripheral portion of the gas container 2c. Hereinafter, the outer shield member 11 is referred to as a first outer shield member 11. Similar to the first outer shield member 11, the second outer shield member 15 is formed of a tubular member having a circular cross section. The first outer shield member 11 is in non-conduction with the head cover 6, but the second outer shield member 15 is in conduction with the head cover 6.

(Action and effect)
As described above, the portion where the electric field concentration is a problem in the gas-insulated on-load tap changer 2 is near the lower end portion of the seal pressing ring 7. Therefore, in the second embodiment, in addition to the inner shield member 14 installed inside the gas container 2c, the second outer shield member 15 is disposed near the seal pressing member 7 and on the outer peripheral part of the gas container 2c. Electric field concentration can be suppressed.

  Further, in the second embodiment provided with the inner shield member 14, the sharp shield-like gap 17 shown in FIG. 4 is not formed between the seal pressing ring 7 and the gas container 2 c, and the inner shield By the functions of the member 14 and the second outer shield member 15, the electric field between the seal pressing ring 7 and the gas container 2c is greatly alleviated, and the interval of the equipotential lines becomes wide (see FIG. 8).

  According to the second embodiment as described above, the effects of the inner shield member 14 and the second outer shield member 15 can be synergistically obtained, and the inner shield member 14 and the second outer shield member 15 are provided. The maximum electric field value in the gas container 2c can be greatly reduced, for example, by about 73%, as compared with the time when it was not. As a result, insulation reliability can be secured while making the device compact.

Third Embodiment
A third embodiment according to the present invention will be specifically described using FIGS. 9 to 11. In the configuration of the third embodiment, the same parts as those of the second embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

(Constitution)
The third embodiment is different from the first embodiment in that the first shield member 11 and the second outer shield member 15 are omitted by omitting the inner shield member 14 as shown in FIGS. It is to have.

(Action and effect)
According to the third embodiment, even if a wedge-shaped gap 17 is formed between the seal pressing ring 7 and the gas container 2c, the electric field can be reduced by the presence of the second outer shield member 15. It can be relaxed. Therefore, the maximum electric field value in the gas container 2c can be reduced, for example, by about 69% as compared with the case where the first and second outer shield members 11 and 15 are not provided. The interval of the equipotential lines can be sufficiently extended (see FIG. 11).

(Other embodiments)
The above embodiments are presented as an example herein and are not intended to limit the scope of the invention. That is, the present invention can be carried out in other various forms, and various omissions, replacements and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and the equivalents thereof as well as included in the scope and the gist of the invention.

  In the above embodiment, both the first outer shield member 11 and the second outer shield member 15 are tube-shaped members having a circular cross section, but the first outer shield member 11 has a curved surface portion on the upper side of the cross section The second outer shield member 15 may be a member provided with a curved surface portion on the lower side of the cross section.

  For example, the first outer shield member 11 and the second outer shield member 15 may not have a circular cross section, and a rectangular belt member in which a portion in contact with the outer peripheral portion of the gas container 2c is in close contact with the outer peripheral surface It may be. In addition, the curvatures of the curved surface portions of the first outer shield member 11 and the second outer shield member 15 and the curvatures of the curved surface portions of the inner shield member 14 can be appropriately changed, and the size, material, etc. can be appropriately selected. is there.

DESCRIPTION OF SYMBOLS 1 ... Transformer tank 2 ... Gas-insulated type tap switching device 2a ... Switching switch 2b ... Tap selector 2c ... Gas container 3, 4 ... Insulating gas 5 ... Tap lead wire 6 ... Head cover 7 ... Seal presser ring DESCRIPTION OF SYMBOLS 8 ... Seal member 9 ... Upper shield board 10 ... Lower shield board 11 ... (1st) outer shield member 12 ... Plane part 13 ... Insulation cylinder 14 ... Inner shield member 14a ... Curved part 15 ... 2nd outer shield member 16 ... gap 17 ... bowl-shaped gap

Claims (9)

A gas container which forms an opening at the upper end and encloses an insulating gas inside;
A head cap fitted in the opening of the gas container;
A sealing member for sealing between the gas container and the head cover;
A seal pressing member for pressing the seal member;
A gas-insulated on-load tap changer comprising: an inner shield member covering a lower end portion of the seal pressing member.   The gas insulation type on-load tap changer according to claim 1, wherein the inner shield member is provided with a curved surface portion on the lower side.   3. The gas-insulated on-load tap switching device according to claim 1, wherein a flat portion is provided at a lower end portion of the seal pressing member.   The gas-insulated on-load tap changer according to any one of claims 1 to 3, wherein the inner shield member is formed of an aluminum plate material.   The gas-insulated on-load tap changer according to any one of claims 1 to 4, wherein the inner shield member is not in contact with the inner circumferential surface of the gas container.   The gas-insulated on-load tap changer according to any one of claims 1 to 5, wherein the inner shield member is electrically connected to the head cover.   The 1st exterior shield member which did not conduct with the said head cover, and provided the curved surface part in the upper side was arrange | positioned in the outer peripheral part of the said gas container, The 1st external shield member characterized by the above-mentioned. Gas-insulated on-load tap changer as described. A second outer shield member electrically connected to the head cover at a position above the first outer shield member and below the seal pressing member at an outer peripheral portion of the gas container;
8. The gas-insulated on-load tap changer according to claim 7, wherein the second outer shield member is provided with a curved surface portion on the lower side. 9. A gas-insulated on-load tap changer according to any one of claims 1 to 8 , wherein shield plates facing vertically are disposed inside the gas container.

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