JPH067139B2 - Surge measurement method for gas-insulated electrical equipment - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to an insulating spacer used mainly in a gas-insulated electric device such as a gas-insulated switchgear using a SF ₆ gas as an insulating medium and a pipeline air-transmitting device. The present invention relates to a surge measuring method for a gas-insulated electric device, which measures the surge voltage in the gas-insulated electric device using an electrode embedded inside.

[Technical Background of the Invention and Problems Thereof] In a gas insulated switchgear and a pipeline air transmission device, many insulating spacers are used to insulate and support a high-voltage conductor in a grounded metal container. This insulating spacer is disclosed, for example, in Japanese Patent Publication No. 54-44106 and Japanese Patent Laid-Open No. 55-15551.
As shown in Japanese Unexamined Patent Publication No. 2, an insulating spacer body made of thermosetting synthetic resin such as epoxy resin supports a high voltage conductor
The flange of this spacer has a buried metal for a mounting bolt embedded therein. Furthermore, since the SF ₆ gas tends to deteriorate the insulation characteristics due to the unequal electric field, the ground shield is integrally embedded around the high-voltage conductor as a countermeasure for this potential, and a grounding metal pad that doubles as a mounting bolt hole is used for this potential. It is usually secured through.

FIG. 3 and FIG. 4 show a longitudinal sectional view of a conventional insulating spacer and a surge measuring device using this insulating spacer. 1
Is a high-voltage conductor, 2 is an insulating gas, and 3 is a grounded container. Four
Is an insulating spacer body. The current-carrying member 41 for joining the high-voltage conductors 1 to each other is cast integrally with the insulating spacer body 4. 6 is a metal flange, which is also cast integrally with the insulating spacer body 4. Reference numerals 71 and 72 are conductive rings that are cast integrally with the insulating spacer body 4, and 71 of these rings is always installed, whereby the connecting portion between the container 3 and the insulating spacer 40 configured as described above. Contributes to the improvement of insulation performance. 7
2 has a structure in which the potential can be floated at any time, either constantly or temporarily, and measures the voltage of the high-voltage side charging unit,
And used for corona measurements. That is, the metal ring 7
When 2 is floating in potential, high voltage conductor 1 and metal ring 7
A voltage proportional to the voltage side charging unit voltage is induced in the metal ring 72 due to the capacitance partial pressure between the two and between the metal ring 72 and the grounded container 3 or the metal flange 6.

By conducting this voltage to the outside through an opening provided in the metal flange 6 by a conductive member that is insulated from the metal flange 6, voltage detection of the high voltage side charging section, that is, voltage measurement and corona measurement, etc. You can

By the way, in the corona measurement in the device using the insulating spacer 40 having the above-described configuration, the terminals are drawn out from the metal ring 72 to the outside of the insulating spacer 40 at two places due to safety requirements. When measuring the surge in the gas insulated switchgear using this insulating spacer 40,
As shown in the figure, a capacitor 21 is connected between one lead terminal 8a and the metal flange 6, and the capacitor 2
The measuring device 20 was connected between the one terminals to perform the measurement, and the other lead terminal 8b was in the open state. However, this conventional insulating spacer has the following drawbacks.

That is, two metal rings 7 are provided in the insulating spacer 40.
It is necessary to cast 1 and 72 integrally with the metal flange 6, which requires a lot of casting man-hours at the time of casting, and the structure is complicated, resulting in high cost.

In addition, it is not preferable to cast a plurality of small metal rings integrally in the insulator mechanically, especially in terms of thermal stress,
It also causes cracks. Therefore, it has been desired that the number of metal rings integrally cast in the insulator be the minimum necessary.

[Object of the Invention] The present invention has been made in view of the above problems, and it is possible to measure a surge voltage by using an insulating spacer having a simple structure, easy manufacturing, and a structure that is preferable in terms of mechanical stress. It is an object of the present invention to provide a method for measuring surge in a gas-insulated electric device.

[Outline of the Invention] In order to achieve the above object, according to the present invention, an insulating spacer having a structure in which an insulating spacer body and a metal flange are separated is used and embedded in the insulating spacer body.
From two ring-shaped electrodes, terminals are drawn out to the outside of the insulating spacer at two locations or at three or more locations evenly arranged, and capacitors of equal capacity are connected between the respective lead terminals and the metal flange. However, the terminal voltage of at least one of these capacitors is measured.

[Structure of Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

The same parts as those shown in FIGS. 3 and 4 are designated by the same reference numerals. FIG. 2 shows a structure of an insulating spacer which has been improved in order to eliminate the drawbacks of the conventional insulating spacer.

In FIG. 2, the high-voltage conductor 1 is supported and arranged in the grounded container 3 filled with the insulating gas 2 via the insulating spacer 40. Usually, a connecting flange 5 is provided at an end of the grounding container 3 to connect the grounding containers 3 to each other. The insulating spacer 40 supports the high-voltage conductor 1 in the grounding container 3 so as to be sandwiched between the connecting flanges 5. The insulating spacer 40 is composed of a metal flange 6 sandwiched between the connecting flanges 5 and an insulating spacer body 4 engaged with the connecting flange 5, and they are separately cast without being integrally cast as in the prior art. Manufactured separately and assembled as a unit when assembling equipment. The insulating spacer body 4 and the connecting flange 5 are joined to each other via an O-ring 31 to maintain gas tightness.

A protrusion 4a is provided on the outer peripheral portion of the insulating spacer body 4 at the middle portion in the thickness direction, while a protrusion 6a is provided on the inner peripheral surface of the metal flange 6 on one side thereof. Then, the metal flange 6 may be fitted into the insulating spacer body 4 from the side where the protrusion 6a does not exist.

A ground shield 71 is embedded in the insulating spacer body 4 concentrically with the conductor 1. In order to integrally cast the insulating spacer body 4 and the ground shield 71, it is necessary to support the ground shield 71 at at least three points in order to align the central axis of the insulating spacer body 4 with the central axis of the ground shield 71. . That is, it is necessary to form the plane of the ground shield 71 for integral casting. Since this support is exposed to the outside of the spacer after casting, the support can be made of metal and can be used as a terminal for surge measurement.

It is best for casting to arrange the supports at three or four points. That is, it is desirable that all the supporting members have the same shape in terms of manufacturing efficiency, and it is preferable to design so that the same force is applied to each supporting point. For example, when a supporting method in which a large force is applied to only one point is adopted, the strength of the supporting tool must be designed in accordance with this maximum strength, and at other supporting points, it is overdesigned and inefficient. Further, if the number of supporting points is small, the force applied to one supporting tool becomes large and strength is required. On the other hand, if the number of supporting points increases, the number of supporting tools increases, but the force applied to one supporting tool decreases, which is advantageous in terms of strength. From the above, in the present invention, the support tools are equally arranged at three points or four points.

And FIG. 1 shows an embodiment of a surge measuring method using the insulating spacer. Ground shield 71
Extraction terminals 8a, 8b, 8c, 8d used as a support tool at the time of casting the insulating spacer are evenly arranged at four locations, and capacitors 21, 22, 23, 24 of equal capacity are connected to the extraction terminal 8
a, 8b, 8c, 8d and the metal flange 6, respectively, are connected, and the terminal voltage of the capacitor 21 among them is measured by the surge measuring device 20.

With the insulating spacer configured as described above, when casting the insulating spacer body, it is sufficient to embed the minimum number of the ground shield 71 and the lead terminals 8a, 8b, 8c, 8d as the supporting metal fittings. Since it is not necessary to cast a lot of filler metal used for conventional flange tightening, it helps improve work and stabilize quality. Further, since the insulating spacer body 4 and the metal flange 6 are separately made, the processing thereof is very easy, and the integration of the both can be achieved by using a stopper and a bolt.

On the other hand, the following main effects are obtained in surge measurement.

(1) Since the surge measuring terminal is grounded at two or more places, the grounding shield 71 does not have a high potential when the surge measuring instrument 20 is attached, and the surge measuring device 20 has a gas It is safe from the reliability of the insulation equipment. That is, the ground shield 71 is always connected to the metal flange 6 and is replaced with the capacitors 21 to 24 only when measurement is performed. At this time, if one terminal is disconnected from the metal flange 6 and the capacitor is attached before disconnecting the other terminals from the metal flange 6, even if all the remaining terminals are disconnected from the metal flange, The potential of the ground shield 71 is suppressed by the previously connected capacitor.

(2) Since the capacitors 21 to 24 are grounded to all the terminals 8a to 8d, the potential of the terminals is suppressed by the capacitors, and there is no dielectric breakdown between the terminals and the metal flange 6. If a capacitor is not connected to any one terminal, that terminal and metal flange 6
It was confirmed in a factory test that a dielectric breakdown occurs between them. This phenomenon occurs for the following reasons. The voltage of a circuit surge or switch surge generated in a gas-insulated device changes by several hundred kV within a short time of 20 ms or less when the surge occurs. With respect to such a large voltage change rate, the ground shield 71 acts as an inductance, and a considerably large voltage is generated in this inductance. This voltage causes insulation breakdown. Since this voltage can be absorbed by the capacitor, if a capacitor is connected to each terminal, there will be no dielectric breakdown between the terminal and the metal flange 6. In the conventional insulating spacer shown in FIG. 3, two indispensable ground shields 71 and 72 are embedded, and the ground shield 71 near the high-voltage conductor 1 is always grounded to the metal flange 6. Such a phenomenon did not occur without connecting a capacitor to one of the extraction terminals.

(3) Since capacitors of equal capacity are connected to all terminals, there is no resonance phenomenon between capacitors and accurate surge measurement is possible. If the terminals are not evenly distributed and / or the capacitors have different capacities, or both, those capacitors will be grounded.
Since they are separated by the inductance component of 1, the voltage instantaneously applied to each capacitor is different at the moment when the surge occurs. Then, each capacitor and the ground shield 71
The resonance phenomenon occurs due to the inductance of, and accurate surge measurement becomes impossible.

[Effects of the Invention] As described above, according to the present invention, the structure is simple,
It is possible to provide a method of measuring a surge of a gas-insulated electric device, which utilizes an insulating spacer that is easy to manufacture and is also preferable in terms of mechanical stress.

[Brief description of drawings]

FIG. 1 is a diagram showing a method of measuring a surge voltage using an insulating spacer to which the present invention is applied, FIG. 2 is a sectional view showing an embodiment of the insulating spacer of FIG. 1, and FIG. FIG. 4 is a vertical sectional view of the spacer, and FIG. 4 is a diagram showing a conventional method of measuring a surge voltage. DESCRIPTION OF SYMBOLS 1 ... High-voltage conductor, 2 ... Insulating gas, 3 ... Grounding container, 4 ... Insulating spacer main body, 5 ... Grounding container flange, 6 ... Metal flange, 8a, 8b, 8c, 8d ... Support metal fittings (drawing terminal), 20 ... Surge measuring instruments 21, 22, 23, 24 ...
Capacitor, 31 ... O-ring, 40 ... Insulating spacer,
41 ... energizing member, 71 ... annular ground shield.

Claims (3)

[Claims] 1. A gas-insulated electric device in which a high-voltage conductor inserted into a grounding container is supported by insulating spacers sandwiched and fixed between connecting flanges of the grounding container. And an insulating spacer body that is engaged with the metal flange and is concentrically embedded with an annular ground shield concentric with the metal flange, and is insulated from the ground shield embedded in the insulating spacer body. A plurality of lead-out terminals are led out to the outside of the spacer, and capacitors of equal capacity are connected between the respective lead-out terminals and the metal flange of the grounding container or the insulating spacer, and one terminal of the capacitors is used for surge measurement. A surge measuring method for a gas-insulated electric device adapted to measure voltage. 2. A lead-out terminal led out from a ground shield,
Claim 1 which is arranged equally on the ground shield.
A method for measuring surge of a gas-insulated electric device according to the paragraph. 3. A surge measuring method for a gas-insulated electric device according to claim 1, wherein the lead-out terminal is a support fitting used when the ground shield is integrally embedded in the insulating spacer body. .