JP3458393B2 - Gas insulated telescopic bus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas insulated stretchable busbar.
In particular, the present invention relates to a gas-insulated expansion busbar suitable for a gas-insulated switchgear that requires a structure for thermally and mechanically protecting the sheath against an arc generated by an electrical accident such as a ground fault.

[0002]

2. Description of the Related Art FIG. 7 shows a side view of a general gas insulated switchgear for one circuit. The main buses 8a and 8b, the circuit breaker 7, and the main equipment of the bushing 1 are connected by a branch bus 4.
For the purpose of absorbing the assembly tolerance between the main components and the thermal expansion and contraction of the branch bus bar 4 in the axial direction, expansion and contraction bus bars capable of absorbing the expansion and contraction amount corresponding to the design amount are installed at various places. The purpose of installing the gas-insulated telescopic busbar is to absorb the vertical undue displacement of the foundation between the main devices , and it is generally called a large excursion bellows, etc. Since the structure of the sheath portion is basically the same, the axial expansion / contraction generatrix will be described here. FIG. 6 shows a general structure of a gas insulated stretchable busbar. The main element is composed of a connecting flange 33 that is a connecting portion with the busbar sheath 41, a bellows-like sheath 31 of the expansion and contraction absorbing portion, and a bellows connecting sheath 32 for connecting the connecting flange 33 and the bellows- like sheath 31 .
Are installed conductor 9 for energizing the circuit current inside the gas insulated telescopic bus containers made from these, the conductor 9 and the container between the, 3～5MPa insulating gas at normal gauge pressure (e.g. S
It is insulated with F ₆ gas, etc.). The conductor 9 is mechanically supported by an insulating spacer or the like, but it is not described here. One conductor 9 depending on the configuration (single-phase circuit)
, Or three (three-phase circuit), but the configuration is the same in terms of the structure of the gas-insulated stretchable busbar. When a circuit current is applied to the conductor 9, the sheath current induced thereby flows through the busbar sheath 41 and the bellows-shaped sheath 31 , but the bellows-shaped sheath 31 is generally thin because it has good elasticity. The corrugated shape is made of a steel plate or a stainless steel plate having a plate thickness. Therefore, when a sheath current is applied, the bellows-shaped sheath 31 locally overheats to cause a temperature rise. Therefore, generally, the busbar sheaths 41 on both sides of the bellows-shaped sheath 31 are connected to bypass the sheath current. Sheath current energizing bar 3
Install 4. Also, as described above, the bellows-shaped sheath
Since 31 is mechanically low in rigidity, the reinforcing ring 36 may be installed in some cases.

When an accident such as a ground fault occurs in the gas-insulated expandable bus bar having such a structure, the sheath is damaged by the internal arc, and the pressure of the internal insulating gas sharply rises at a high temperature to damage the sheath. A so-called burn-through phenomenon occurs in which an object is struck and blown outside. This phenomenon is extremely dangerous for maintenance personnel, and means for preventing the burn-through phenomenon is needed. As a means to prevent the burn-through phenomenon, it is possible to install an external pressure relief device or widen the gas compartment in order to suppress the rise in gas pressure, but there are difficulties in terms of economic efficiency and accident recovery, Increasing the thickness of the sheath is the simplest and most effective means. In the case of gas-insulated busbars and major equipment such as gas-insulated switchgear, mechanical rigidity is required, so even though the design thickness does not consider burn-through, the thickness is almost enough to withstand burn-through. In the case of the sheath for use, the thickness is inevitably thin for the purpose of its installation as described above, which is the weakest point portion against burn-through.

[0004]

BRIEF Problem to be Solved] Conventionally, with respect to burn-through phenomenon, the phenomenon to unclear part number, were often not been implemented countermeasures against the sheath gas insulated telescopic bus. For example, the configuration shown in JP-A-55-155509 JP <br/> and Sho 56-136442,
The above-mentioned bar for energizing the sheath current is installed inside the bellows-shaped sheath (conductor side) as a cylindrical container, and it seems to be effective as a burn-through measure. A connecting flange was required to secure an effective cross-sectional area, and the airtight surface of the insulating gas increased. In addition, it is necessary to make the energizing cylindrical bar also expandable and contractible, which causes a problem in that the structure becomes complicated.

An object of the present invention is to provide a burn-through countermeasure with a small airtight surface and a simple structure , and to collect particles.
It is to provide a gas-insulated stretchable bus bar with a catching function .

[0006]

The gas-insulated stretchable mother of the present invention
The wire is a flexible bellows with an insulating gas sealed inside.
-Shaped sheath and a conductor arranged in the bellows-shaped sheath
And an arc-resistant conductive material inside the bellows-shaped sheath.
A protective sheath made of material is provided and
There are several holes for capturing particles at the bottom of the screen.
And are characterized.

[0007]

[Function] The protective sheath supported by welding or bolt connection on the inside (conductor side) of the bellows-shaped sheath is an arc-resistant conductive material (for example, copper plate or steel plate coated with conductive paint). ), The arc generated in the gas-insulated busbar is circulated from the conductor through the protective sheath to the grounded container and does not damage the thin plate portion of the bellows-shaped sheath.

Further, by providing a small hole for trapping particles in the lower part of the protective sheath in the vertical direction, particles existing in the gas insulating bus bar and impairing the insulating performance are trapped from the small hole between the protective sheath and the bellows-like sheath, Make sure that it cannot move again within the insulated busbar.

[0009]

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a gas-insulated stretchable bus bar according to an embodiment of the present invention. The gas-insulated stretchable bus bar is connected to a bus bar sheath 41 or another equipment container through a connecting flange 33. . On the other hand, the connecting flange 33 is integrally formed with the bellows-shaped sheath 31 by a welding structure or the like via a portion of the bellows connecting sheath 32 having a plate thickness generally similar to that of the busbar sheath 41. . The bellows-shaped sheath 31 has a corrugated shape, and a reinforcing ring 36 is arranged to increase rigidity. The sheath current energizing bar 34 is arranged at several places in the circumferential direction by bypassing the outside of the bellows-shaped sheath 31 by bolt connection or the like from the flange portion of the busbar sheath 41 . Therefore, the sheath current induced by the circuit current during the normal operation does not pass through the bellows-shaped sheath 31 but flows through the sheath current conducting bar 34.
Through the sheath 41 for the busbars. Inside the sheath 41 for the busbar and the bellows-shaped sheath 31 having the ground potential, a conductor 9 having a high voltage potential for conducting a circuit current is arranged and insulated by an insulating gas 10. The protective sheath 35 is arranged inside (on the side facing the conductor 9 ) so as to protect the bellows-shaped sheath 31 by bolt connection to a protective sheath mounting bracket 37 installed in advance in the bellows connecting sheath 32 portion. FIG. 2 shows a connection example of the protective sheath connection portion. When mounting the protective sheath, it is better for the high-voltage equipment to have a structure such as a counterbore to prevent the head of the bolt from traveling on the conductor-side inner surface of the protective sheath 35 so that insulation breakdown due to electric field concentration does not occur. On the other hand, it is preferable. Further, the protective sheath mounting member 37 may be arranged not in the entire circumference but in several places uniformly in the circumferential direction so as to secure a sufficient cross-sectional area for processing the arc current.

Assuming now that dielectric breakdown occurs from the conductor 9 and a ground fault current flows to the ground potential side, the busbar sheath 4
No. 1 is composed of a thick member that can withstand this ground fault current as described above, but there is no problem. However, when the protective sheath 35 is not provided, current flows through the thin bellows-shaped sheath 31 and burn-through. Generate. According to the invention,
Since the ground fault current flows through the conductive protective sheath 35 to the thick bellows connecting sheath 32, the bellows-shaped sheath can be protected from the arc and burn-through does not occur. The material of the protective sheath 35 may be a conductive member having a low resistance to a ground fault current, such as a copper material, or a member in which a conductive paint is applied to the surface of a metal material.

In FIG. 3, a small hole 35a for capturing particles is installed on the lower surface of the protective sheath 35 in the vertical direction. Particles (dust) generated at the time of assembly or from the sliding part of the switch are a major cause of impairing the dielectric strength of the insulating gas, but move in the metal sheath vibrating with the AC frequency. By providing a small hole in the protective sheath 35 that is slightly larger (about several mm) than the size of these conceivable particles, the particles that have moved can be captured. The captured particles are stored in the corrugated portion of the bellows sheath 31, but this portion has a small levitation electric field due to the influence of the protective sheath 35, and cannot escape again into the sheath through the small hole.

FIG. 4 shows a structure in which the protective sheath is integrally welded in advance in the gas-insulated expansion / contraction busbar, and is functionally the same as the embodiment of FIG. If the gas-insulated expandable busbar is large, the protective sheath becomes a heavy object. Therefore, if there is a difficulty in assembling the protective sheath in the gas-insulated expandable busbar, it is desirable to have such an integral structure. Also, if there is a problem in strength with a cantilever structure where there is only one welding or bolt connection, the protective sheath is divided into two pieces as shown in Fig. 5 and they are connected to each other to leave a gap. It is also possible to configure so that expansion and contraction of the insulating expansion and contraction busbar can be dealt with.

[0015]

The gas-insulated expandable bus bar of the present invention described above
Says that the protective sheath is placed inside the bellows-like sheath.
Since it is installed, the gas-tight surface does not increase and the configuration is simple.
Burn-through measures can be taken, and also a protective sheath
Since there are multiple holes at the bottom of the
It has the effect of combining the catch function.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a gas-insulated stretchable bus bar according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of FIG.

FIG. 3 is a cross-sectional view of a gas-insulated stretchable bus bar according to an embodiment of the present invention.

FIG. 4 is a sectional view of a gas-insulated stretchable bus bar according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view of a gas-insulated stretchable bus bar according to an embodiment of the present invention.

FIG. 6 is a cross-sectional view of a conventional gas-insulated stretchable busbar.

FIG. 7 is a side view of one line of a gas-insulated switchgear that uses a gas-insulated stretchable busbar.

[Explanation of symbols]

9 ... Conductor, 10 ... Insulating gas, 31 ... Bellows-like sheath, 32 ... Bellows connecting sheath, 33 ... Connection flange, 34 ... Sheath current energizing bar, 35 ... Protective sheath,
35a ... Small holes for capturing particles, 36 ... Reinforcing ring, 37 ... Protective sheath mounting bracket, 41 ... Busbar sheath.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02G 5/08 361

Claims (2)

(57) [Claims] And 1. A retractable bellows sheath enclosing the internal insulating gas, a conductor disposed on the bellows-like sheath, a protective consisting arc resistant conductive material on the inside of the bellows-shaped sheath A sheath is provided and the
A plurality of holes for capturing particles are installed under the protective sheath.
A gas-insulated stretchable busbar that is characterized by being punctured. 2. A two-piece protective sheath is fixed to the flange sides on both sides of the bellows-like sheath, and a gap is provided between the two pieces of the protective sheath so as to accommodate expansion and contraction of the bellows-like sheath. Claim 1 characterized by the above.
The gas-insulated telescopic bus bar described.