JPS589473Y2 - insulation spacer - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an insulating spacer used for gas insulated switchgear, gas insulated busbars, etc.

Generally, insulating spacers are used for the purpose of holding conductors and separating gas in single-phase or three-phase sealed busbars.

The structure consists of an insulating body in which the conductor or the metal fittings supporting the conductor are integrally molded with thermosetting epoxy resin, and a spacer to alleviate the uneven electric field caused by the flange of the conduit or dust adhering to the surface of the insulating body. Consists of a shield ring placed concentrically with the center of the

The effect of this shield ring can suppress the decline in corona starting voltage and dielectric strength due to contamination near the flange to some extent, but corona discharge is likely to occur not only near the flange but also due to peeling between the center conductor and the resin. Corona discharge in voids and creeping corona generation due to contamination of the insulating material near the conductor are also major problems.

If these discharges continue for a long period of time during operation, there is a risk of mechanical deterioration due to a decrease in dielectric strength or the occurrence of cracks due to corona erosion.

Therefore, in order to improve the safety and reliability of the device, it is necessary to periodically monitor the presence or absence of corona discharge in the spacer from outside the conduit of the sealed busbar.

For this purpose, it has been developed to provide a shield ring for measurement.

That is, as shown in Fig. 1 a, t), a shield ring 3 and terminals 4 and 4' disposed on the outer surface of an insulating spacer are integrally manufactured on an insulating body 2 that is airtightly molded on a conductor 1. The molded parts are embedded and molded into one piece.

The shield ring 3 is usually made of a hollow or solid conductive material such as a metal having a circular cross section.

The terminals 4, 4' of the shield ring 3 are connected to the conduit at the same potential (at the same potential) by means of lead wires or the like using bolts for attaching an insulating spacer to the flange E of the conduit (not shown).

Therefore, when measuring corona discharge, etc., the lead wire is removed, and the electrostatic induction is determined by the ratio of the capacitance between the conductor 1 and the shield ring 3, and the capacitance between the shield ring 3 and the conduit (not shown), that is, the ground. A voltage is induced between the shield ring 3 and ground.

Therefore, for the safety of the measuring circuit and the operator, a large capacitance is connected to the terminal portion and the voltage is divided to a sufficiently low level before measurement is performed.

Even when measuring with this method, a relatively high voltage is generated even at normal operating voltage due to the capacitance partial pressure caused by the capacitance of the shield ring for measurement and the conductor.

For example, even at an operating voltage of 275 KV, a voltage of about 2 KV is generated.

Therefore, since the shield ring is normally connected to the conduit, no particular problem occurs, but in order to measure corona discharge, a high voltage is induced when disconnecting from the conduit. However, unless a large capacity capacitor is connected to the input terminal of the measurement circuit before measurement, there will be some safety issues for the workers.

As a means to solve this problem, an insulating spacer having the structure shown in FIG. 2 can be considered.

That is, the shield rings 3, 3' are embedded in the ground side of the insulating main body 2 in which the conductor 1 is embedded integrally.

Here, the shield rings 3 and 3' have the same cross section and the same inner diameter, and are arranged with a gap within the diameter of the strands of the shield rings 3 and 3'.

The shield ring 3 is connected by a lead wire 7 to an insulating spacer and a bushing 5 to be tightened with a bolt (not shown) of a conduit, and set to the same ground potential as the conduit through the tightening bolt.

On the other hand, the shield ring 3' is used to measure corona discharge, etc., and is drawn out to the outer surface at the measurement terminal 6.

By the way, the electrostatic voltage induced in the shield ring 3' is determined by the ratio of the capacitance between the conductor 1 and the shield ring 3' and the capacitance between the shield ring 3' and the grounded shield ring 3, and most of the electrostatic voltage is Since the capacitance is between 1 and 3', most of the voltage is shared between 1 and 3'.

Therefore, since only a low voltage is induced between 3' and 3,
It can be said that the voltage is sufficient for safety.

In addition, since the terminal 6 of the shield ring 3' is not normally used for measurements such as corona discharge, it can be connected to a conduit power line, etc. by connecting it with a lead wire using a bolt attached to the flange of the conduit (not shown). It works more safely against various types of surges that invade.

However, the insulating spacer having the structure shown in FIG. 2 has the following drawbacks.

That is, in the case of shield rings 3 and 3' having the same ring diameter, especially in the case of a cone-shaped insulating spacer, the equipotential line is directed from the conduit connecting part on the convex side of the insulating spacer toward the inside of the insulating spacer main body 2. Therefore, the electric field on the left side of the diagram becomes significantly higher than that at the conduit connecting portion on the concave side of the insulating spacer, which is a drawback in terms of insulation performance.

Therefore, the present invention has been developed in view of the above points, and the object thereof is to obtain an insulating spacer that allows safe corona measurement of the insulating spacer and eliminates defects in insulation performance.

In order to achieve this purpose, according to the present invention, the first and second shield rings are embedded in the ground side of the insulating main body (the diameter of the first shield ring is made smaller than the diameter of the second shield ring). Also, the first shield ring is placed closer to the ground than the first shield ring (the first shield ring is guided through the terminal device to the outer surface of the insulating spacer) , the second shield ring is connected to the conduit.

An embodiment of the present invention will be described below with reference to FIGS. 3 to 6, in which the same parts as in FIGS. 1 and 2 are denoted by the same reference numerals.

Here, FIGS. 3 to 5 all show different embodiments of the present invention.

In other words, the inner diameter of the shield ring 3 to be grounded is smaller than the inner diameter of the shield ring 3' for measurement.

This allows the electric field to be brought closer to 3, so that 3' can be shielded.

Also, by doing this, the induced voltage in the shield ring 3' can be reduced.

In particular, in the case of a cone-shaped spacer as shown in Fig. 4, the shield ring 3 to be grounded should be placed on the convex side.
It is clear from electric field calculations that this effect is even more remarkable.

In addition, especially in the case of a desk type, as shown in FIG. The electrostatic voltage will be extremely low.

FIG. 6 shows an embodiment of a terminal device according to the present invention, which is intended to have the terminal 6 of the measuring shield ring 3' at the same potential as the conduit except during measurement.

That is, the present invention is applied to cases where the flange portion of the insulating spacer 2 is replaced with a bushing and a metal ring 5 is used.

The grounding shield ring 3 is fixed to the metal ring 5 by welding, bolting, or the like.

In this example, welding is shown.

The terminal portion is constructed as shown in FIG. 6C.

A nipple 10 is tightened and fixed to the metal ring 5 via a screw 10'.

A guide 11 made of an insulating material such as polyacetal resin or nylon resin is fixed within the nipple 10 by means of adhesive or the like.

A spring 13 and a pressure contact 12 are disposed on the inner surface of the guide 11 so that the sliding part 14 in the nipple 10 can slide freely. A grounding metal fitting 15 which also serves as a stopper to prevent this is tightened to the nipple 10& through a screw 15'.

The shield ring 3' for measurement is grounded by the following action except during measurement.

That is, the terminal 6 of the shield ring 3' and the grounding fitting 1
5, the pressure contact 12 and the measuring element 14 are pressed by the spring 13 (thereby, the same potential as that of the metal ring 5 is obtained via the threaded portions 15' and 10').

Therefore, when measuring corona discharge, etc., the probe 20 is inserted into the hole of the grounding fitting 15, and insulation is maintained by stroking the probe 14 by δ, and measurement is possible due to the action of the shield ring described above. .

That is, when the probe 20 is removed, the shield ring 3' returns to the same grounded state as before, making it extremely easy to work safely.

As explained above, according to the present proposal, there are two
One shield ring is used for measurement and the other for grounding, and the ring diameter of the measurement shield ring is larger than the grounding shield ring diameter. It is possible to provide an insulating spacer that has excellent insulation performance and can be safely operated.

[Brief explanation of the drawing]

Figures 1a and 5 are sectional views and front views of a spacer showing a conventional example, Figure 2 is a sectional view of a spacer preceding the present invention, and Figures 3 to 5 are sectional views of different embodiments of the present invention. , FIGS. 6a, b, and c are a sectional view, a front view, and a detailed sectional view for explaining the measurement terminal used in the present invention. 1...conductor, 2...mainly insulated, 3...
...Shield ring, 5...Butshu 6
...Measurement terminal, 7...Lead wire.

Claims (3)

[Scope of utility model registration request] (1) A conductor is disposed inside to interconnect pipes filled with insulating gas, and to support the conductor disposed in the pipes (in the insulating spacer thus formed, The first and second shield rings are embedded in the ground side of the insulating spacer, and the first shield ring with the larger ring diameter is connected to the exposed outer surface of the insulating spacer through the terminal device. An insulating spacer characterized in that a second shield nong having a smaller ring diameter than the second shield nong can be connected to a conduit. (2) An insulating spacer is formed in a cone, a second shield ring connected to the conduit is disposed on the convex side of the cone shape, and a first shield ring is provided with a terminal device for taking out the cone shape.
The insulating spacer according to claim (1), wherein the shield ring is arranged on the concave side. (3) The insulating spacer according to claim (1) of the utility model registration, in which a second shield ring is disposed inside the first shield ring, and both shield rings are disposed on the same cross section.