JPH0865835A - Insulating spacer - Google Patents

Abstract

PURPOSE: To make a gas insulated switchgear small in size by improving the withstand voltage characteristic of a conductor piercing part which divides a gas chamber of the insulated switchgear. CONSTITUTION: A truncated-cone-shaped tubular part is provided in projection on the outer periphery of an electrode 2 coaxially with this electrode on the opposite sides of an insulating layer 2 pierced by the electrode 2. The gradient of a slant of the insulating layer at this tubular part is made less than 60 deg. to the axis of the electrode 2. Withstand voltage values on the opposite sides of the insulating layer 2 are made equal for an overvoltage impressed on the surface of the electrode 2 and gas pipes 3A and 3B, while a discharge generated by the overvoltage applied between the surface of the electrode 2 and the gas pipes 3A and 3B is made not from the surface of the insulating layer 2, but through an insulating gas between the surface of the electrode 2 and the gas pipes 3A and 3B. Thereby a withstand voltage characteristic is improved and made stable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating spacer for airtightly partitioning a gas chamber inside a gas insulating switchgear.

[0002]

2. Description of the Related Art Insulating spacers have been conventionally used as an insulated conductor for hermetically partitioning a partition wall of a gas chamber of a gas insulated switchgear. FIG. 6 is a sectional view showing an example of a conventional insulating spacer for three phases.

In FIG. 6, cylindrical gas chambers 9A and 9B are provided.
The insulating layer 1 is attached to the annular insulating spacer provided at the boundary of
Embedded electrodes 22 are arranged inside D in a regular triangle in a plan view (not shown). Also, in the central part on the outer peripheral side,
A ring-shaped electrode 23 is embedded during casting for electric field relaxation, and this electrode 23 is pulled out to the outside by a lead wire 12B and grounded.

Both sides on the outer peripheral side of the insulating layer 1D are annularly welded to the connecting portions of the cylindrical containers 3A and 3B via an O-ring 7C inserted in an annular groove formed in the insulating layer 1D. After being inserted between the flanges 4A and 4B, the airtightness is maintained between the gas chambers 9A and 9B by being held by bolts. Conductors 5A and 5B are connected to both ends of the embedded electrode 22, respectively, and are connected to electric equipment (not shown) housed in the gas chambers 9A and 9B.

The insulating layer 1D is formed by casting using an excellent insulating material such as epoxy resin, and its cross-sectional shape is projected to one gas chamber 9A side as disclosed in JP-A-2-119521. The cross section has a substantially convex shape. That is, by projecting to the gas chamber 9A side on one side, the creeping distance of the slope portions 1d1 and 1d2 is increased, and the withstand voltage characteristic is improved. The thickness of the insulating layer 1D is the same as that of the sloped portion 1d except for the flange portion into which the O-ring 7C is inserted.
Including 1 and 1d2, they have almost the same thickness.

[0006]

By the way, in the insulating spacer thus constructed, the conductor 5A connected to the electrode 22 embedded in the insulating layer 1D having a convex cross section,
The electric field strength on the surface of 5B is determined approximately by the outer diameters of the conductors 5A and 5B and the inner diameters of the flanges 4A and 4B.

However, in the conductors 5A and 5B connected via the electrode 22 embedded in the insulating layer 1D, the slope portion 1d2 is interposed between the conductor 5B and the flange 4B on the gas chamber 9B side. The electric field strength on the flange 4B side of the conductor 5B becomes particularly high. This is because the dielectric constant of the insulating layer 1D is as high as 4 to 5 while the dielectric constant of the insulating gas is about 1.
This is because the gap between d2 and the conductor 5B is narrower than the gap between the conductor 5A and the inner surface of the container 3A.

Therefore, in order to increase the diameter of the flanges 4A and 4B to widen the gap between the conductor 5B and the slope portion 1d2 and to extend the creepage distance of the slope portions 1da and 1d2, the gas chamber 9A side The protrusion height is increased to suppress the increase in electric field strength. Then, the outer diameters of the containers 3A and 3B become large, and the width must be increased, so that the outer shape of the gas insulated switchgear increases.

Therefore, an object of the present invention is to prevent an increase in the outer shape of the gas-insulated switchgear caused by the supporting portion of the conductor penetrating the partition wall of the gas chamber of the gas-insulated switchgear and to improve the withstand voltage characteristic. Is to get.

[0010]

According to the present invention, an electrode is provided through a disc-shaped insulating layer whose outer peripheral side is held at the end of a gas chamber, and both sides of the insulating layer are provided on the outer periphery of the electrode. It is characterized in that a cylindrical portion having a conical discoid shape is provided so as to be coaxial with the electrode.

[0011]

The electric field strength between the surface of the electrode and the inner surface of the gas chamber is equal on both sides of the outer periphery of the insulating layer, and the discharge generated between the surface of the electrode and the inner surface of the gas chamber is more void than the surface of the insulating layer. Occurs first, the discharge starting voltage becomes stable, and becomes higher.

[0012]

An embodiment of an insulating spacer according to the present invention will be described below with reference to the drawings. FIG. 1 shows claims 1, 2, and 3.
FIG. 7 is a cross-sectional view showing an example of the insulating spacer of the invention according to claim 4, and is a view corresponding to FIG. 6 shown in the conventional technique. In FIG. 1, a plan view (not shown) has a disk shape, and embedded electrodes 2 for three phases are embedded in positions of an equilateral triangle in an insulating layer 9 formed symmetrically in the front-back direction of FIG. ing.

A semicircular groove 1b is formed on the gas chamber 9A side of the outer peripheral portion of the insulating layer 9, and a groove 1c is also formed on the gas chamber 9B side. Grounding layers 7A and 7B coated with a conductive paint are formed in these grooves 1b and 1c, and O-rings 8A and
8B through the flange 4A on the gas chamber 9A side and the gas chamber 9B
It is fixed to the side flange 4B.

Further, cylindrical containers 3A and 3B are attached to the flanges 4A and 4B by welding. In addition,
A hollow large-diameter portion 2a following the small-diameter portion 2b is formed at each end of each embedded electrode 2, and the end of the insulating layer 1A covers the central portion of the small-diameter portion 2b. The outer periphery of the corner portion of the large diameter portion inside the small diameter portion 2b is largely chamfered, and the electric field strength of the triple junction portion composed of the small diameter portion 2b and the insulating layer on the outer periphery of the small diameter portion 2b and the insulating gas is relaxed. Has been done.

As shown in FIG. 6 of the prior art, the ends of the conductor 5A are connected to both ends of each electrode 2 by fitting them through contact rings (not shown) inside the large diameter part 2b. , Are connected to electrical equipment housed in the gas chambers 9A, 9B.

Here, the insulating layer 1A, as shown in FIG. 1, protrudes in the front-rear direction in the shape of a circular disc to form a slope 1b.
As shown in FIG. 2 which shows a partially enlarged detailed view of the embedded electrode 2 on the left side of FIG. 1 on the gas chamber 9A side, the angle θ sandwiched between the sloped portion 1e and the embedded electrode 2 is as shown in FIG. For the reason described below in 58
It is a degree.

FIG. 3 is a graph showing the results of the analysis by the inventors of the electric field intensity distribution when the angle θ of the inclined surface portion 2e of the insulating layer 2 is changed in the insulating spacer shown in FIG. In FIG. 3, the curve E ₀ is from the small diameter portion 2b to the container 3
The absolute value of the maximum electric field strength on the creeping surfaces of the inner peripheral surfaces of A and 3B. The curve E1 indicated by the alternate long and short dash line is the normal component of the absolute value E ₀ and the curve E ₂ indicated by the alternate long and two short dashes line.
Is a tangential component of the absolute value E ₀ .

As shown in FIG. 3, when the angle θ is changed,
The absolute value E ₀ hardly changes, but the curves E ₁ and E
₂ shows the opposite characteristics of the upper right and the lower right, which intersect at the point where θ is 60 degrees. That is, the normal component and the tangent component that make up the absolute value E ₀ at the point where θ is 60 degrees become equal to each other,
When is greater than 60 degrees, the tangential component is large, and conversely, when θ is less than 60 degrees, the normal component is large.

Based on this analysis example, as a result of examining the dielectric breakdown phenomenon of two samples at an angle θ of 60 ° as a boundary, as shown in the discharge path B in the insulating gas in FIG. It was also found that the discharge progresses in the gap between the gases, and at 60 degrees or more, the discharge progresses along the creeping surface of the insulating layer 2 as in the discharge path C shown in FIG.

It is considered that, of the components of the electric field strength on the creeping surface, the normal component is the electric field for ionizing the insulating gas and the tangential component is the electric field propagating on the creeping surface. Therefore, the discharge generated in the insulating gas space showed a dielectric strength with little fluctuation in the value of the breakdown voltage, whereas the discharge developing along the creeping surface was easily influenced by the state of the creeping surface and the fluctuation of the discharge voltage was large. .

The voltage value of the dielectric breakdown largely depends on the electric field strength on the outer circumference of the large diameter portion 2a, but a value of 60 degrees or less, where the variation of the breakdown voltage is small, is higher and the insulation performance is excellent. It was

The reason why the fluctuation of the discharge voltage on the creeping surface is large is that the discharge crawling on the creeping surface causes a destabilization of the discharge due to a subtle difference in the resistivity of the creeping surface, adhesion of foreign matter and minute unevenness. It is believed that

The ground layers 7A and 7B formed on the outer peripheral side of the insulating layer 1A can alleviate the electric field between the ground such as the flanges 4A and 4B for three phases at a time, thus maintaining stable insulating performance. be able to.

Next, FIG. 4 shows another embodiment of the insulating spacer according to claims 1, 2, 3 and 4 and shows an example of an insulating spacer having improved interphase dielectric strength. FIG.
In, the creeping distance including the slope portion 1d in the interphase direction is longer than the creeping distance including the slope portion 1e to the ground layers 7A and 7B with respect to the embedded electrode 2.

As a result, the region under the condition that the electric field strength component formed on the creeping surface satisfies the condition of normal component ≧ tangential component, and the dielectric strength in the interphase direction can be improved. Therefore, the dielectric strength of the insulating spacer configured as described above is in the interphase direction> to-ground direction, and the insulation coordination with other electric devices can be achieved. In addition, as shown in FIG. 4, since the thickness of the insulating layer in the central portion becomes thin, the insulating layer 1
The amount of resin forming B can be reduced, and the weight can be reduced.

Next, one embodiment of the insulating spacer of the invention described in claim 5 is shown in the sectional view of FIG. In FIG. 5, embedded electrodes 2 for three phases are embedded in the insulating layer 1D,
Further, a pair of rings 11 is embedded so as to surround each embedded electrode 2.

When the insulating layer 1C is thick, the ring 11 is formed in two upper and lower stages as shown in FIG. 5, and is connected to the flange 4B by the lead wire 12A to be at the ground potential.

The outer periphery of the insulating layer 1C has an O-ring 8
It is fixed to the flanges 4A and 4B via A and 8B, and is fixed in a state where airtightness is maintained. In the insulating spacer thus configured, the center portion in the interphase direction is set to the ground potential by the ring 11. A voltage between the phases is applied between the buried electrodes 2, but a ground potential is present at a substantially middle portion, so that the potential between the phases is grounded.

Therefore, the dielectric breakdown occurs in the buried electrode 2 for all three phases to the ground, and the dielectric breakdown in the interphase direction can be prevented. Here, the embedding depth of the ring 11 is required to be about several mm, and the electric field strength of the slope portion 1e closest to the ring 11 is relaxed. This also applies to the outside.

Therefore, although it is an insulating spacer for three phases, it is a single-phase insulating spacer which is independent for each phase in terms of insulation and suppresses dielectric breakdown between the phases, so that insulation coordination with other electric equipment can be achieved. It becomes an insulating spacer.

Even in the single-phase insulating spacer, the buried electrode is provided with a stepped portion in order to relieve the local concentration of the electric field due to the triple junction at the interface between the buried electrode and the insulating layer. By keeping the angle of 60 degrees or less and forming a groove on the outer periphery to obtain the ground potential, it is possible to obtain an insulating spacer having excellent dielectric strength. Furthermore, even at the end of a conductor such as a current transformer or transformer formed by casting the outside with an insulating resin, one end is provided, but a step difference of a convex portion is provided near the end of the conductor to form an insulating layer. By maintaining the angle, it is possible to stabilize the dielectric strength of the surface.

[0032]

As described above, according to the present invention, the electrode is provided through the disk-shaped insulating layer whose outer peripheral side is held at the end of the gas chamber, and the conical discoid cylinder is coaxial with the outer periphery of the electrode. By projecting parts on both sides of the insulating layer, the electric field strength between the surface of the electrode and the inner surface of the gas chamber is made equal on both sides of the outer periphery of the insulating layer, and applied between the surface of the electrode and the inner surface of the gas chamber. A discharge generated by a voltage is generated in the air gap before the surface of the insulating layer to increase the discharge start voltage, thereby improving the withstand voltage characteristics of the supporting portion of the conductor that penetrates the partition wall of the gas chamber of the gas insulated switchgear. Since it has been raised, it is possible to obtain an insulating spacer that can prevent an increase in the outer shape of the gas insulated switchgear.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of an insulating spacer of the invention described in claims 1, 2, 3 and 4.

FIG. 2 is a partially enlarged detailed view of FIG.

FIG. 3 is a graph showing the action of the insulating spacers of the present invention according to claims 1, 2, 3, 4 and 5.

FIG. 4 is a cross-sectional view showing another embodiment of the insulating spacer of the present invention according to claims 1, 2, 3 and 4.

FIG. 5 is a sectional view showing an embodiment of an insulating spacer of the invention according to claim 5;

FIG. 6 is a sectional view showing an example of a conventional insulating spacer.

[Explanation of symbols]

1A, 1B, 1C ... Insulating layer, 2 ... Electrode, 2a ... Large diameter part,
2b ... small diameter part, 3A, 3B ... container, 4A, 4B ... flange, 5A, 5B ... connecting conductor, 6 ... insulating gas, 7A, 7B
... ground layer, 8A, 8B ... O-ring, 9A, 9B ... gas chamber, 11 ... ring.

Claims (5)

[Claims] 1. An insulating layer, and electrodes which are provided so as to penetrate through the axis of the insulating layer and have conductors connected to both ends thereof. The insulating layer is provided so as to project in the central portion and the outer peripheral side is an end portion of the gas chamber. An insulating spacer including an annular flange portion that is airtightly held, and a conical disk-shaped tubular portion that is formed on both side surfaces of the central portion of the flange portion and that is coaxially formed on the outer periphery of the electrode. 2. An insulating layer, and an electrode penetrating the shaft center of the insulating layer and having conductors connected to both ends thereof, wherein the insulating layer is a groove formed by projecting in the center and grounded. An annular flange portion whose outer peripheral side is airtightly held at the end of the gas chamber,
An insulating spacer, which is a conical disc-shaped cylindrical portion that is formed on both inner side surfaces of the flange portion and is coaxially formed on the outer periphery of the electrode. 3. The insulating spacer according to claim 1 or 2, wherein an angle formed between the electrode and the inclined surface of the conical discoidal cylinder is less than 60 degrees. 4. A disk-shaped insulating layer having an outer periphery airtightly held by an end of an adjacent gas chamber, and a plurality of disk-shaped insulating layers penetrating around the center of the insulating layer and having conductors connected at both ends. And an insulating spacer having, in the insulating layer, a cylindrical disk-shaped cylindrical portion formed on the outer periphery of the electrode. 5. The insulating spacer according to claim 4, wherein a ground ring is embedded in the insulating layer coaxially with the electrode.