JPH03222621A - Gas-insulated spacer - Google Patents

Abstract

PURPOSE:To make an apparatus smaller, as it maintains insulating properties, and to eliminate machining to reduce a manufacturing cost by forming the longitudinal section of a central conductor into an H-shape and by providing a first groove shaped into a ring, in the manner of coaxially facing the central conductor, and a second groove. CONSTITUTION:A central conductor 21 forms an H-shape in the longitudinal section, and an insulator 22 is formed by a main body part 23 on the central conductor 21 side, a flange 24 thinner than the main body part 23 on the outer peripheral end side and a U-shaped groove 25 as a first groove. Also, a semicircular groove 26 is provided as a second groove in the vicinity of the boundary between the insulator surface 22a and U-shaped groove 25. The H-shielded central conductor 21 forms a recessed part in the boundary of the insulator 23, the central conductor 21 and an insulating gas to prevent a triple junction. When the width of the U-shaped groove is selected in a specified manner, it is possible to suppress the electric field strength of the insulator surface. Thus, the diameter of a spacer is reduced and working properties are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a gas insulated spacer that is attached to gas insulated electrical equipment and is capable of dividing the gas in each compartment.

(Prior Art) FIG. 2 shows an example of a gas insulated switchgear equipped with a conventional gas insulated spacer. In addition, Figures 3 and 4 are
1 shows a cross-sectional view of a conventional gas insulating spacer, cut along one side along the center line.

The gas insulated switchgear includes a circuit breaker 2.2 in a grounded metal container 1 as shown in FIG. Disconnector 3. The busbar 4° cable head 5 is housed, and the storage locations are separated by grounded metal partition plates 1a to prevent the spread of accidents.

For this reason, these devices are connected by a gas insulating spacer (hereinafter referred to as a spacer) 6 attached to a grounded metal partition plate 1a, and via a conductor 7 via this spacer 6.

Further, since a gas insulated switchgear generally has a configuration of several panels in rows, each panel is electrically connected by a bus bar 4. Here, as above, in order to prevent the accident from spreading, the busbar room of each panel is
Since it is partitioned by a grounded metal partition plate 1a, the spacer 6
The busbar 4 of each panel is connected through this.

On the other hand, each room divided by a grounded metal partition plate 1a is
Since it is filled with an insulating gas 8 such as SF6 gas,
The spacer 6 is configured to keep each room airtight.

As shown in FIG. 3, the spacer 6 is composed of a central conductor 9 and a disc-shaped insulator 1o formed by casting an epoxy resin material coaxially with the central conductor 9. Note that screw holes (not shown) for connecting the conductor 7 are provided at both end portions of the center conductor 9.

The method of fixing the spacer 6 is to use a grounded metal partition plate 1a as a mounting base 1, provide a screw hole Lla and an O-ring groove 11b inside the screw hole Lla, and connect the mounting base 11 and a fixing flange 12 made of a metal material. Insert the outer circumferential end of the insulator 1o between the holes and secure with bolts 13. At this time, the O-ring 14 is inserted into the O-ring groove 11b to provide a gas seal between the insulator 10 and the mounting base 11.

By the way, the feature of the spacer 6 shown in the figure is that the insulator 10
．． In order to prevent a triple junction occurring at the interface between the mounting base 11 and the fixed flange 12 and the SF6 gas, the shape of the insulator 10 at the portion sandwiched between the mounting base 11 and the fixed flange 12 is made convex. The contact angle between the mounting base 11 and the fixed flange 12 is 90' D or more, and the ends (inner peripheral surfaces) of the mounting base 11 and the fixed flange 12 on the side facing the center conductor 9 have a curvature sufficient to satisfy the withstand pressure. It is.

With such a configuration, the electric field on the ground side can be relaxed without providing a buried electrode for electric field relaxation in the insulator 1o. Further, in order to increase the mechanical strength of the spacer 6 due to short-time current, etc., the bonding area and thickness of the insulator 10 near the bonding portion of the center conductor 9 are increased.

The configuration of the spacer 6 shown in FIG. 4 is the same as the spacer 6 shown in FIG. 3, except for the method of relaxing the electric field on the ground side. As a method for alleviating the electric field on the ground side (including avoiding triple junctions), the internal electrode 15 is buried in the insulator 10 sandwiched between the mounting base 11 and the fixed flange 12.

(Problems to be Solved by the Invention) The insulation performance of the conventional spacer 6 is based on the diameter of the center conductor 9, the radius of curvature of the end of the mounting base 11 and the fixed flange I2 facing the center conductor 9, and the center conductor 9 and the mounting base. 11 or the fixed flange 12, and it has been effective to increase these dimensions in order to improve insulation performance. In other words, in order to reduce the diameter of the spacer while maintaining insulation performance, it is necessary to increase the diameter of the center conductor 9 and increase the curvature of the ends of the mounting base 11 and fixed flange 12 on the side opposite to the center conductor 9.
Increasing these means increasing the diameter of the spacer, and there is a limit to reducing the diameter of the spacer.

In addition, the center conductor 9 of the mounting base 11 and the fixed flange 12
In order to have a curvature at the opposite end, this part needs to be machined. However, since this part is semicircular, it cannot be machined from only one side, and the setup must be changed in the middle and machined from the other side as well.
Moreover, in a three-phase circuit, the mounting base 11 has to be machined three times and the fixed flange 12 has to be machined three times, a total of six times, and these processes require a large manufacturing cost, making it expensive.

Furthermore, the method for avoiding triple junctions is
In the spacer 6 shown in the figure, it is necessary to make the ground side end of the insulator IO convex and to give the mounting base 11 and fixed flange 12 the aforementioned curvature, which increases the mounting dimensions on the ground side. In the spacer 6 shown in FIG.
It is necessary to embed the internal electrode 15 in the ground side end of the insulator 10, and the insulator 10 and the internal electrode 15 may peel off, causing partial discharge or cracks, or the position of the internal electrode 15 may shift during casting, which may cause malfunction. In particular, if a crack occurs, it is expected that a fatal accident will occur as an electrical device. As described above, there are some difficulties in the casting technique, and a solution to these problems has been desired.

Therefore, the objects of the present invention are: (1) To reduce the size and reduce the cost while maintaining insulation performance.

(2) To reduce the cost by eliminating the need for machining to form the curvature of the mounting base and fixed flange.

(3) When avoiding triple junctions, eliminate difficulties in casting technology and improve reliability and productivity by not increasing the size of the ground side attachment part or embedding internal electrodes in the insulator.

Kokichi provides gas insulated spacers that meet your needs.

(Means for Solving Issues) The present invention consists of a center conductor and an insulator in which epoxy resin is cast coaxially with the center conductor, and the insulator is attached to gas-insulated electrical equipment to separate the gas divisions of each compartment. In the gas insulated spacer, the longitudinal cross-sectional shape of the center conductor is H.
A thin flange portion is formed in the shape of a letter and has a step at the outer peripheral end of the insulator, and the step portion has a width equal to or greater than the thickness of the ground metal member constituting the fixing portion,
and a ring-shaped first groove coaxially facing the center conductor, and having a circular arc in the axial direction of the center conductor on the first groove side near the boundary between the first groove and the creeping surface of the insulator, and A ring-shaped second groove coaxial with the center conductor is provided, and a ground layer having the same potential as the fixed portion is provided in the first groove and the flange portion up to the second groove. .

(Function) The flange part and the fixing part for fixing it are at the same potential, and no acute angle part is formed across the creeping surface of the insulator, so triple junctions can be prevented. Also,
Since the ground layer is provided with a semicircular groove at the boundary between the creeping surface of the insulator and the U-shaped groove, the equipotential line near the boundary between the ground layer and the creeping surface of the insulator is lifted, and triple junctions in this vicinity can also be prevented. Since the high-voltage side has an H-shielded center conductor, the boundary between the insulator, the center conductor, and the insulating gas is a recess, which can prevent triple junctions.

Furthermore, the insulation performance is determined by the diameter of the center conductor, the radius of curvature of the H shield, and the thickness of the insulator on the top of the H shield.

It is influenced by the distance between the ground layer and the center conductor, the radius of curvature of the ground layer, etc., but if these dimensions are fixed, it is influenced by the creeping shape of the insulator. Since the electric field strength of the H shield becomes stronger, by increasing the thickness of the insulator on the upper part of the H shield and selecting a predetermined width of the first groove on the ground side, the electric field strength on the creeping surface of the insulator can be reduced. It can be controlled. In addition, unlike conventional gas insulated spacers, the ground side is not exposed and present in the insulating gas space, but instead is surrounded by an insulator.
The electric field strength on the ground side can be reduced by α15, which is the product of the dielectric constant ratio of the insulating gas and the epoxy resin of 1:5 by the coefficient α depending on the shape, and there is also the effect of suppressing the overall electric field strength. However, 1≦α≦5.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of one embodiment of the present invention taken along the center line.

In the figure, the spacer 20 is composed of a center conductor 21 and a disc-shaped insulator 22 formed by casting an epoxy resin material coaxially with the center conductor 21.

In this configuration, the center conductor 21 has an H-shaped vertical cross section, and includes a disc-shaped portion 21a and an annular outer peripheral protrusion 21b formed on the outer peripheral side of the disc-shaped portion 21a and having a semicircular tip. Screw holes (not shown) for connecting the conductor 7 are provided on both sides of the disc-shaped portion 21a.

Further, the insulator 22 has a main body portion 23 on the center conductor 21 side,
A flange portion 24 that is thinner than the main body portion 23 on the outer peripheral end side
And, the width above and below this flange part 24 is equal to or greater than the respective thicknesses of the fixed flange I2 and the mounting base 11 (indicated by T).
The U-shaped groove 25 has a U-shaped groove 25.

This U-shaped groove 25 has a portion 25 facing the mounting base 11.
a and a portion 25b facing the fixing flange 12. When fixing to the mounting base 11 using the fixing flange 12, it can be mounted from either the front side or the back side of the mounting base 11 (in other words, the directionality when fixing can be changed). In order to eliminate
The width is based on the thicker of either the mounting base 11 or the head of the fixed flange 12. Further, when the distance in the direction facing the center conductor 21 is D (mu), and the voltage applied here when the rated voltage is applied is V (kv), g≧
It is provided in a ring shape coaxial with the center conductor 21 while maintaining the V relationship.

Furthermore, U near the boundary between the insulator creeping surface 22a and the U-shaped groove 25
A semicircular groove 26 is provided on the side of the groove 25 over the entire circumference of the main body portion 22. Here, the radius (indicated by γ) of the semicircular groove 26 is related to the magnitude and distribution state of the ground side electric field strength of the insulator creeping surface 21a. Also, the starting point of the semicircular groove 2B and the creeping surface 2 of the insulator
The distance to 2a (indicated by t) is related to the magnitude of the ground side electric field strength of the insulator creeping surface 22a.

On the other hand, a position a distance t from the boundary between the insulator creeping surface 22a and the U-shaped groove 25, that is, from the starting point of the semicircular groove 26 to the deepest part of the U-shaped groove 25 and the flange portion 24, is coated with copper plating or conductive paint. A ground layer 27 is formed by coating.

Next, on the high-voltage side, the outside of the outer circumferential protrusion 21b of the center conductor 21 is molded (H shield) so that the corners are arcuate and covered with an insulator 22.

In the spacer 20 configured as described above, the O-ring 14 is inserted into the O-ring groove 11b provided in the mounting base 11 in the same way as the conventional spacer 6 described above, and the flange portion 24 is placed on the mounting base 11. The fixing flange 12 is placed over the flange portion 24 and fixed by screwing the bolt 13 into the screw hole 11a of the mounting base 1.

In addition, in the case of this fixing method, the ends of the mounting base 11 and the fixing flange 12 on the side opposite to the center conductor 21 are not made to protrude into the U-shaped groove 25. In addition, the mounting base 11 and the fixed flange 1
The opposite end of the center conductor 21 of No. 2 is not provided with a curvature as in the conventional case.

Next, the operation of the spacer 20 with the above configuration will be explained. When the spacer 20 is fixed to the mounting base 11, the flange portion 24 is at ground potential and the mounting base 11 and the fixed flange 12 are at the same potential, and the mounting base 11 and the fixed flange 12 do not protrude from the U-shaped groove 25. In addition, since the ground layer 27 is formed, the spacer 20
creepage, mounting base 11, fixed flange 12 and SF
Triple junctions occurring at the interface of six gases can be prevented.

Also, a radial groove 2 is provided at the boundary between the insulator creeping surface 22a and the U-shaped groove 25.
Since 6 is set at ground potential, the insulator creepage 22
Until the equipotential line near the boundary between a and the ground layer 27 is raised, a triple junction occurring in this portion can be prevented. However, due to the rise of the equipotential line due to the semicircular groove 26, the creeping surface 22a of the insulator near the semicircular groove 26
At the top, dense equipotential lines appear, causing local electric field concentration. Therefore, in order to prevent this, the semicircular groove 28
The starting point is a distance t from the boundary between the insulator creeping surface 22a and the U-shaped groove 25.

Further, electric field relaxation on the ground side is performed by the ground layer 27 of the U-shaped groove 25, and the mounting base 11 and the fixed flange 12
is completely hidden by the ground layer 27 when viewed from the center conductor 21, so even if the shapes of the ends of the mounting base 11 and the fixed flange 12 on the side facing the center conductor 21 have sharp corners, there is no problem in terms of insulation. No.

On the other hand, the flange *24 of the spacer 20 does not have to be as thick as the insulator IO of the conventional spacer 6 shown in FIG. Since the U-shaped groove 25 is provided, the center conductor 2
The insulator 22 on the side closer to the center conductor 21 is thicker and can have a larger bonding area with the center conductor 21 without creating a step in the middle of the creeping surface.

In addition, the insulation performance of the spacer 20 is determined by the diameter of the center conductor 21, the radius of curvature of the H shield, and the insulator 21 on the top of the H shield.
, the distance ff between the ground layer 27 and the center conductor 21, and U
Although it is influenced by the radius of curvature of the U-shaped groove 25, in particular, the U-shaped groove 2
It is greatly influenced by the shape of 5. Instead of existing in the insulating gas space with the ground side exposed like in the past, the insulator 2
Since the U-shaped groove 25 surrounded by 2 corresponds to this, the insulator 22 is divided by the value α15 (1≦α≦5), which is the dielectric constant ratio of the insulating gas and the epoxy resin, l:5, multiplied by the coefficient α depending on the electrode shape. The electric field strength on the ground side surrounded by the insulator can be lowered, and the electric field strength of the entire insulator creeping surface 21a is also suppressed.

Furthermore, on the high voltage side, the center conductor 2I, which has an H-shaped vertical cross section, is H-shielded, so the boundaries between the insulator 22, the insulating gas, and the center conductor 21 are recessed to prevent triple junctions. However, the electric field strength at the tip of the H shield becomes high and a local electric field concentration area occurs on the creeping surface 22a of the insulator, so in order to prevent this, the thickness of the insulator 22 on the top of the H shield is set to a predetermined size. .

According to the experimental results, when the rated voltage is from 20KV to 140KV in SF6 gas near atmospheric pressure, the radius γ of the semicircular groove 26 is T/20≦γ≦T/2 with respect to the width T of the U-shaped groove. ,
The distance t (mm) from the boundary between the insulator creeping surface 22a and the U-shaped groove 25 to the starting point of the radial groove 26 is 3≦t≦1O1H The wall thickness L of the shield is L-10 to 30, and the height of the center conductor 21 is By setting the sum of the width of the flange portion 24 and the width (2XT) of the upper and lower U-shaped grooves 25 to approximately 70% of the axial length of the outer peripheral protruding portion 21b, the desired effect can be achieved. I found out that I can get it.

Therefore, in the embodiment with the above configuration, it is easy to alleviate the electric field on the ground side and avoid triple junctions, and there is no need for machining (to form curvature) of the mounting base 11 and fixed flange 12 as in the conventional case. In addition, since there is no need to embed an electrode inside the ground side portion of the insulator, casting becomes easy and productivity and reliability can be improved.

Furthermore, since the electric field strength at each part can be suppressed, the size can be reduced while maintaining insulation performance.

Note that in the above explanation, the spacer 20 is
Although we have described the case where the method is used in air (gas), it is clear that it can also be applied in air. However, in the air, there is no triple junction, so there is no effect.

[Effects of the Invention] As explained above, according to the present invention, when a spacer and a disconnector are conventionally housed in a gas-insulated switchgear, the pitch between these phases is different, so it is difficult to bend the connecting conductor or when assembling. However, the spacer of the present invention can suppress the electric field strength at each part, so the diameter of the spacer can be reduced while maintaining insulation performance, making it easier to connect with other equipment. The pitch between the phases can be made the same,
Improves workability and conductor processability.

In addition, since the opposing ends of the mounting base and fixed flange on the center conductor side do not have curvature, machining for this purpose is no longer required six times in a 3-phase circuit, greatly improving the machinability of the mounting base and fixed flange. be done.

Furthermore, it is possible to easily avoid triple junctions and relax the electric field on the ground side, eliminating the need for embedded electrodes in the insulator, making casting easier, eliminating the risk of cracks and partial discharges, and improving reliability (1) workability (2). Yield can be improved.

In addition, by using the spacer of the present invention, it is possible not only to reduce the size of the spacer, but also to reduce the size of the entire gas-insulated electrical equipment and improve workability and ease of assembly.

Yield and reliability can be improved, and the overall cost can be reduced.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention, with one side cut along the center line, FIG. 2 is a side view of a gas-insulated switchgear related to the present invention, and FIG. 3 is a conventional gas-insulated switchgear. A cross-sectional view showing one side of the insulating spacer cut along the center line.
FIG. 2 is a cross-sectional view showing a conventional gas insulating spacer, which is different from the one shown in the drawing, with one side cut along the center line. 11... Mounting base 21... Center conductor 23... Main body portion 25... U-shaped groove 27... Ground layer 12... Fixed flange 22... Insulator 24... Flange portion 26 ...Semi-circular groove (8733) Agent Patent attorney Yoshiaki Inomata (and 1 other person) Houki 2 Kaze

Claims (1)

[Claims] In a gas insulated spacer, which is composed of a center conductor and an insulator in which epoxy resin is cast coaxially with the center body, and which is attached to gas insulated electrical equipment to enable gas division of each compartment, the longitudinal section of the center conductor is The insulator is formed into an H-shape, and a thin flange portion with a step is formed at the outer peripheral end of the insulator, and the step portion has a width equal to or greater than the thickness of the grounding metal member constituting the fixing portion. and a ring-shaped first groove coaxially facing the center conductor, and a ring-shaped first groove in the axial direction of the center conductor on the first groove side near the boundary between the first groove and the creeping surface of the insulator. a ring-shaped second groove having a circular arc and coaxial with the center conductor, and further, the first groove and the flange portion up to the second groove are provided with the same potential as the fixed portion. A gas insulating spacer characterized by being provided with a ground layer.