JP2016207962A - Gas insulation type load-time tap switching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas insulation type load-time tap switching device which attains reduction of a maximum electric field value and improves a voltage resistance property.SOLUTION: A gas container 2c is provided in which an insulation gas is encapsulated and a changeover switch is accommodated. A head cover 6 is fitted to an opening in an upper end of the gas container 2c. A seal member 8 is disposed between the gas container 2c and the head cover 6, and a seal pressing ring 7 is provided for pressing the seal member 8. At an outer peripheral part of the gas container 2c and lower than a lower end of the seal pressing ring 7, an outer shield member 11 is provided which is not conducted with the head cover 6. An inner shield member 14 which is conducted with the head cover 6 is provided in such a manner that the inner shield member is in non-contact with an inner peripheral surface of an insulation cylinder 13 and that the lower end of the seal pressing ring 7 is covered. The inner shield member 14 includes a curved surface part at an opposite surface side of a charging part side.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a gas-insulated on-load tap switching device.

  In recent years, substations installed in central Tokyo are becoming more compact and are shifting to underground types due to the difficulty of large-scale operation on the ground. Along with the transition to underground substations, gas-insulated transformers in which an insulating gas is sealed in a hermetically sealed container have become mainstream as transformers arranged in substations. This is because the gas-insulated transformer is excellent in environmental performance and safety.

  Normally, a transformer connected to the grid incorporates an on-load tap switching device to stabilize the system voltage, but in response to the transformer becoming a gas insulation system, a gas insulated load An hour tap switching device is employed. In the gas-insulated load tap changer, a gas container having a hermetically sealed structure is attached to the opening of the transformer tank, and a switching switch is accommodated in the gas container. Further, a tap selector is disposed below the gas container and is connected to the transformer side via a tap lead wire.

JP 2013-247170 A

  With the increase in underground substations installed in the city center, it is required to reduce the size of the equipment that constitutes substations, and the gas-insulated on-load tap changer is also required to be compact. ing. Although it is essential to increase the withstand voltage characteristics for downsizing the device, it is important to suppress local electric field concentration in order to achieve this. In particular, in the switching switch, the effective tap is switched without interrupting the circuit. Therefore, it is a problem to reduce the maximum electric field value inside the gas container that houses the tap.

  Embodiments of the present invention have been proposed to solve the above-described problems, and provide a gas-insulated on-load tap switching device with a reduced maximum electric field value and improved withstand voltage characteristics. With the goal.

In order to achieve the above object, the gas-insulated on-load tap switching device according to the embodiment of the present invention includes the following components (1) to (5).
(1) A gas container in which an opening is formed at the upper end and an insulating gas is sealed inside.
(2) A head cover that fits into the opening of the gas container.
(3) A seal member that seals between the gas container and the head lid.
(4) A seal pressing member that presses the sealing member.
(5) An internal shield member that covers a lower end portion of the seal pressing member.

The perspective view of 1st Embodiment. 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 the 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 with reference to FIGS. The first embodiment is a gas-insulated on-load tap switching device, which is characterized by a structure related to ground insulation. Before describing this structure, the overall configuration of the gas-insulated load tap changer will be described with reference to FIG.

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

  A tap selector 2b that selects a pair of tap positions is disposed below the gas container 2c. A tap lead wire 5 corresponding to each tap potential is drawn from a winding of a transformer (not shown), and by connecting these tap lead wires 5 to the tap selector 2b, the transformer and the on-load tap switching device. 2 is connected to the circuit.

(Structure related to ground insulation)
A structure related to ground insulation of the gas-insulated load tap changer will be described with reference to FIGS. 1 and 3 show the vicinity of the upper end of the gas container 2c. A head cover 6 is fitted into 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 lid 6 is made of a metal material having a cylindrical portion extending downward, and the cylindrical portion of the head lid 6 is fitted into the opening in the upper part of the gas container 2c.

  A seal member 8 is disposed between the gas container 2c and the head cover 6 so as to seal the both. A seal press ring 7 for pressing the seal member 8 is installed on the lower end surface of the cylindrical portion of the head cover 6. Yes. The seal retainer 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).

  A tube-shaped outer 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 external shield member 11 is a member that is not electrically connected to the head cover 6.

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

(Configuration of main parts)
FIG. 3 is a cross-sectional view of the corner stand of part A in FIG. As shown in FIG. 3, a flat surface 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 surface 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 is attached to the flat surface portion 12 of the seal pressing ring 7. The inner shield member 14 is electrically connected to the head cover 6.

  The inner shield member 14 is provided with a curved surface portion 14a having a semicircular cross section. The curved surface portion 14 a is formed so as to cover a part of the flat surface portion 12 of the seal retainer ring 7 and the bolt 7 a joined to the seal retainer ring 7. The curved surface portion 14a is disposed so as to cover the flat surface portion 12 of the seal pressing ring 7 partway. For this reason, 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)
In general, the portion where electric field concentration is a problem in ground insulation of the gas-insulated load tap changer 2 is in the vicinity of the lower end of the seal retainer ring 7. Therefore, as shown in FIG. 4, it is conceivable to form a curved surface portion directly at the end of the seal retainer 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, despite the formation of the curved surface portion, strong electric field concentration still occurs in the vicinity of the lower end portion of the seal retainer ring 7, and the equipotential lines remain steep.

  In the first embodiment, the internal shield member 14 is attached so as to cover the lower end portion of the seal retainer ring 7 and the curved surface portion 14a is provided on the internal shield member 14 in the first embodiment. Since the inner shield member 14 is a member independent of the seal pressing ring 7, the curved surface portion 14 a having a semicircular cross section can be easily provided, and the surface of the curved surface portion 14 a draws a gentle curve.

  Moreover, a gap 16 is formed between the end portion of the curved surface portion 14a and the inner peripheral surface of the gas container 2c, and the end portion 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 retainer ring 7 and the gas container 2c can be relaxed, the occurrence of electric field concentration is suppressed, and the interval between equipotential lines is widened.

  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%, compared to when the inner shield member 14 is not provided. Thereby, even if the apparatus is made more compact, it is possible to ensure excellent insulation reliability and contribute to improvement of the ground insulation performance. Even when a mixed gas 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 that the occurrence of electric field concentration is ensured. It is possible to prevent.

  Moreover, since the inner shield member 14 is formed of an aluminum plate material, the withstand voltage characteristic can be improved efficiently. Furthermore, in the first embodiment, since the lower end portion of the seal retainer ring 7 is merely formed with the flat surface portion 12, it is not necessary to perform processing for reducing the electric field on the seal retainer ring 7, and the manufacturing cost can be reduced and the economy can be reduced. It is possible to increase the 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 portions are denoted by the same reference numerals and description thereof is omitted.

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

(Action and effect)
As described above, the portion where the electric field concentration becomes a problem in the gas-insulated tap switching device 2 is near the lower end of the seal retainer 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 in the vicinity of the seal pressing member 7 and on the outer periphery of the gas container 2c. Electric field concentration can be suppressed.

  Further, in the second embodiment including the inner shield member 14, the sharp wedge-shaped gap 17 shown in FIG. 4 is not formed between the seal pressing ring 7 and the gas container 2c, and the inner shield is not formed. The action of the member 14 and the second outer shield member 15 greatly relaxes the electric field between the seal pressing ring 7 and the gas container 2c, and the interval between equipotential lines is widened (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 obtained synergistically, 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%, compared with the case where there was no such case. Thereby, insulation reliability can be ensured while making the apparatus compact.

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

(Constitution)
The third embodiment differs from the first embodiment in that, as shown in FIGS. 9 to 11, the inner shield member 14 is omitted and the first outer shield member 11 and the second outer shield member 15 are replaced. Is to have.

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

(Other embodiments)
The above embodiment is presented as an example in the present specification, and is not intended to limit the scope of the invention. In other words, the present invention can be implemented in various other 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 equivalents thereof in the same manner as included in the scope and gist of the invention.

  In the above embodiment, the first outer shield member 11 and the second outer shield member 15 are both tube-shaped members having a circular cross section, but the first outer shield member 11 is a curved portion on the upper side of the cross section. The second outer shield member 15 may be a member provided with a curved 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. Further, the curvature of the curved surface portions of the first outer shield member 11 and the second outer shield member 15 and the curvature of the curved surface portion of the inner shield member 14 can be changed as appropriate, and the size, material, etc. can be selected as appropriate. is there.

DESCRIPTION OF SYMBOLS 1 ... Transformer tank 2 ... Gas insulation type load tap changer 2a ... Switching switch 2b ... Tap selector 2c ... Gas container 3, 4 ... Insulating gas 5 ... Tap lead wire 6 ... Head cover 7 ... Seal press ring DESCRIPTION OF SYMBOLS 8 ... Seal member 9 ... Upper shield board 10 ... Lower shield board 11 ... (1st) outer shield member 12 ... Planar part 13 ... Insulating cylinder 14 ... Inner shield member 14a ... Curved surface part 15 ... Second outer shield member 16 ... Gap 17 ... Wedge-shaped gap

Claims (10)

A gas container that forms an opening at the upper end and encloses an insulating gas therein;
A head lid that fits into the opening of the gas container;
A sealing member for sealing between the gas container and the head lid;
A seal pressing member for pressing the sealing member;
A gas-insulated on-load tap switching device comprising an inner shield member that covers a lower end portion of the seal pressing member.   The gas-insulated on-load tap switching device according to claim 1, wherein the inner shield member has a curved surface portion on a lower side.   The gas insulation type on-load tap switching device according to claim 1 or 2, wherein a flat portion is provided at a lower end portion of the seal pressing member.   The gas-insulated on-load tap switching device according to any one of claims 1 to 3, wherein the inner shield member is formed of an aluminum plate.   The gas-insulated on-load tap switching device according to any one of claims 1 to 4, wherein the inner shield member is not in contact with the inner peripheral surface of the gas container.   The gas-insulated on-load tap switching device according to any one of claims 1 to 5, wherein the inner shield member is electrically connected to the head cover.   The outer peripheral part of the said gas container has arrange | positioned the 1st outer shield member which provided the curved-surface part on the upper side which is not electrically connected with the said head cover. The gas insulated tap switching device according to the description. A second outer shield member that is electrically connected to the head cover at a position above the first outer shield member and below the seal pressing member in the outer periphery of the gas container;
The gas-insulated on-load tap switching device according to claim 7, wherein the second outer shield member has a curved surface portion on a lower side. A gas container that forms an opening at the upper end and encloses an insulating gas therein;
A head lid that fits into the opening of the gas container;
A sealing member for sealing between the gas container and the head lid;
A seal pressing member for pressing the seal member;
On the outer periphery of the gas container, a first outer shield member that is not electrically connected to the head cover and has a curved surface portion on the upper side is disposed,
In the outer peripheral part of the gas container, a second external shield member that is electrically connected to the head cover is disposed at a position above the first external shield member and below the seal pressing member,
The gas-insulated on-load tap switching device, wherein the second outer shield member has a curved surface portion on the lower side.   The gas-insulated on-load tap switching device according to any one of claims 1 to 9, wherein a shield plate facing the vertical direction is disposed inside the gas container.

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