JP2000003644A - Switching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switching device capable of immediately damping a direct-current voltage arising by switching operation. SOLUTION: This device, a disconnector, is equipped with a metallic container 11 filled with an insulating gas 12 at a fixed pressure, a plurality of conductors 13a, 13b and shields 17a, 17b, disposed in the metallic container 11 and supplied with a voltage, and a switching part comprising a fixed contact 15 and a movable contact 16 performing switching operation, and is made up so that electron emission is prevented in areas of the shields 17a, 17b, which may emit electrons more than a predetermined quantity when supplied with a voltage, by covering surfaces thereof by insulators 19. Part of the surface of each shield 17a, 17b is provided with a region where no insulator 19 exists and a ground portion 20 is exposed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switchgear, and more particularly to a switchgear capable of efficiently attenuating a DC voltage component generated by the switching operation.

[0002]

2. Description of the Related Art FIG. 7 is a diagram showing a configuration of a conventional disconnector. In the figure, reference numeral 1 denotes a metal container in which an insulating gas 2 is sealed, which is grounded. 3a, 3b are disposed in the metal container 1, and conductors to which a high voltage is applied, 4 are conductors 3a,
3b is a support portion formed of an insulator for supporting each inside the metal container 1.

[0005] Reference numerals 5 and 6 denote fixed contacts and movable contacts formed to contact and separate the conductors 3a and 3b. Reference numerals 7a and 7b are electrically connected to the conductors 3a and 3b, respectively. It is a shield for alleviating. Reference numeral 8 denotes an insulating rod for operating the movable contact 6.

The conventional disconnector is configured as described above, and the shields 7a and 7b are regions where a predetermined amount or more of electrons can be emitted when a voltage is applied.
The surface of 7b is covered with a dielectric film as an insulator to prevent this electron emission. The reason for forming the dielectric film will be described in detail below.

[0005] Fig. 8 shows "IEEE Trans. On P".
WRD vol. PWRD-2, no. FIG. 3C is a view showing the effect of covering the electrode surface with a dielectric, shown in FIG. In the figure, the horizontal axis represents the value of the effective area of the electrode (the area of the portion having an electric field of 90% or more of the maximum electric field intensity), and the vertical axis represents the value of the breakdown electric field (E) with respect to the theoretical breakdown electric field (Ed). .

As apparent from FIG. 1, when no treatment is performed on the electrode surface, the breakdown electric field decreases from the theoretical value according to the area thereof. However, when a dielectric film is formed on the electrode surface, the breakdown electric field is reduced. It can be seen that the electric field rises to about the theoretical value.
For this reason, the surfaces of the shields 7a and 7b are formed so as to be covered with the dielectric film.

Next, FIG. 9A is a circuit diagram showing a part of a system using the disconnector configured as described above.
Reference numeral 9 denotes a circuit breaker, and reference numerals 10a and 10b denote disconnectors configured as described above. FIG. 9B shows the section A shown in FIG.
FIG. 5 is a diagram showing a change in voltage between a conductor between sections A and a grounded metal container when the system is operated.

[0008]

The conventional disconnecting switch is constructed as described above. For example, as shown in FIG. 9, when the circuit breaker 9 is opened and the disconnecting switches 10a and 10b are opened, the section A
, A DC voltage having the same value as the peak value of the operation voltage remains at the maximum. When the DC voltage remains in this manner, the insulator in each device is charged with a time constant inherent to the insulator, and the electric field shifts from a capacitance distribution to a resistance distribution (a commonly used insulator). The time constant has one hour or more).

Conventionally, in an AC device, an electric field is designed for a capacitance distribution such as an AC or a lightning impulse. When the capacitance distribution shifts to a resistance distribution, an unexpected electric field concentration occurs and the dielectric strength is remarkably increased. It was a factor to lower it. FIG. 10 shows a potential distribution of a part of the disconnector shown in FIG. 7 when the resistance distribution is changed from the capacitance distribution. FIG. 10A shows equipotential lines in the capacitance distribution.
(B) shows equipotential lines in the resistance distribution. FIG.
As is clear from FIG. 0 (b), when the resistance distribution becomes
It can be seen that electric field concentration occurs at points P and Q in the figure.

As a means for solving this problem, it is conceivable to change the configuration while paying attention to the electric field design in a DC electric field. However, this may hinder the downsizing of the equipment and the simplification of the configuration of the insulator. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a switchgear having a high reliability and which can be formed without taking a DC electric field into consideration.

[0012]

Means for Solving the Problems Claim 1 according to the present invention.
The switchgear has a metal container in which an insulating gas is sealed at a predetermined pressure or a vacuum inside, a plurality of conductors disposed in the metal container, and a voltage is applied, and An opening / closing unit for performing contact / separation; in each of the conductors, in a region where a predetermined amount or more of electron emission can occur when a voltage is applied as it is, the surface of each conductor is covered with an insulator to emit electrons. In a switchgear which is prevented, a portion where a background portion of a conductor having no insulator is exposed is provided on the surface of a part of the conductor in the region.

According to a second aspect of the present invention, there is provided the switchgear according to the first aspect, wherein:
The electric field on the conductor surface is the same.

According to a third aspect of the present invention, there is provided the switchgear according to the first or second aspect, wherein the ground portion of the conductor is formed so as to include the highest electric field in the conductor. is there.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, embodiments of the present invention will be described. FIG. 1 is a diagram showing a configuration of a disconnector as a switchgear according to Embodiment 1 of the present invention.
FIG. 3 is a view of the disconnector shown in FIG. 1 as viewed from the arrow direction II on the line B, and FIG. 3 is a view of the disconnector shown in FIG. 1 as viewed from the arrow direction III on the line B.

In FIG. 1, reference numeral 11 denotes a metal container in which an insulating gas 12 is sealed, which is grounded. 13a and 13b are conductors disposed in the metal container 11 and applied with a high voltage.
It is assumed that the conductor 13a is connected to a power supply and the conductor 13b is connected to a circuit breaker. 14a and 14b are the conductors 13a, 1
3b is a support portion formed of an insulator for supporting each inside the metal container 1.

Reference numerals 15 and 16 denote fixed contacts and movable contacts formed as open / close portions for connecting / disconnecting the conductors 13a and 13b.
a, 13b, which are electrically connected to each other and serve as a shield for relaxing the electric field of each of the contacts 15 and 16. Reference numeral 18 denotes an insulating rod for operating the movable contact 16.

The shields 17a and 17b are
As shown in FIG. 2 and FIG. 3, since a region where a predetermined amount or more of electron emission can occur when a voltage is applied, the shield 17
The surfaces of a and 17b are covered with an insulator 19 (for example, made of a dielectric film). Then, at the highest part of the electric field in the shields 17a and 17b in that region, a band is formed in the circumferential direction of the shields 17a and 17b.
A ground portion 20 where no insulator 19 exists is formed on the shields 17a and 17b.

Since the conductors 13a and 13b are regions where no more than a predetermined amount of electrons are emitted when a voltage is applied, the surfaces of the conductors 13a and 13b may or may not be covered with an insulator. Good.

The operation of the disconnector according to the first embodiment configured as described above will be described. First, movable contact 1
When the conductors 13a and 13b are separated by 6, for example, a DC voltage as shown in FIG. 9A remains on the conductor 13b side. When the remaining DC voltage has a negative polarity, electron emission due to field emission or the like occurs from the background portion 20 formed on the shield 17b on the conductor 13b side. If the remaining DC voltage has a positive polarity, the ground portion 20 formed on the shield 17a on the conductor 13a side
Electron emission due to field emission or the like occurs.

As a result, the remaining DC voltage can be attenuated faster than the conventional decay time of only the insulator. FIG. 4 shows an example of dark current measurement by electron emission between the disconnector poles. This example was measured when a DC voltage of about 400 kV remained, and it can be seen that a dark current of about 80 nA flows in the initial stage.

On the other hand, since the combined resistance value (R) of the insulator of the disconnector is about 1 × 10 ¹⁴ Ω, the leakage current value (I) of the insulator is about 4 nA, and the dark current is about 20 nA. It turns out that it is about twice as large. Where the residual DC voltage is
The amount of attenuation (ΔV) that is attenuated only by the insulator is given by the formula I = C ·
It is obtained from ΔV / Δt. At this time, assuming that the capacitance (C) in the remaining section of the DC voltage (for example, the section on the conductor 13b side) is 500 pF, the attenuation ΔV is 14.4 in 30 minutes.
kV.

If the average current for 30 minutes is 30 nA, the attenuation due to the dark current is 108 kV in 30 minutes. It can be seen that the attenuation is very rapid compared to the case where the attenuation is caused only by the insulator. . Therefore,
Before the transition to the resistance distribution (about 1 to 2 hours), the voltage can be attenuated to a voltage level that does not cause a problem in insulation.

The disconnector of the first embodiment configured as described above has a structure in which a part of the shield 17a and 17b is provided.
Since the ground portion 20 is provided, the DC voltage generated by the opening / closing operation at the ground portion 20 can be rapidly attenuated, so that the disconnector does not need to be designed in consideration of the DC electric field. Therefore, the size of the apparatus can be easily reduced.

If the electric field in the background portion is not uniform, electrons are emitted only from a portion of the background portion where the electric field is high, but the background portion 20 is shielded by the shield 1.
Since a band is formed in the circumferential direction of 7a and 17b and the electric field on the surface of the background portion 20 is the same, electron emission occurs in all regions of the background portion 20, so that the DC voltage is efficiently attenuated. Can be. In addition, the ground part 2
Since 0 is formed so as to include the highest electric field portion on the shields 17a and 17b, the electron emission amount is maximized, and the DC voltage can be attenuated more quickly.

Embodiment 2 FIG. In the first embodiment described above, the example in which the conductors of the switchgear are in contact with and separated from each other has been described. Hereinafter, the conductor portion connected to the switchgear will be described. 5 and 6 show a part of the configuration of a switchgear according to Embodiment 2 of the present invention. If a ground portion is formed in any part of the switchgear, the remaining DC voltage is efficiently attenuated. It is a figure for explaining whether it can be made to do.

FIG. 5 shows a supporting portion 14c for supporting the conductor 13b.
And shields 17c to 17f as a part of the conductor formed to alleviate the electric field in the vicinity of the shields 17d and 14d, the shields 17c to 17f generate more than a predetermined amount of electron emission when a voltage is applied. Therefore, the surfaces of the shields 17c to 17f are covered with an insulator 19. Then, a portion where the ground portion 20 is exposed, which is not covered with the insulator 19 on a part of the surface of the shields 17d and 17f, is formed in the circumferential direction.

FIG. 6 shows a case where the shield as shown in FIG. 5 does not exist near the supporting portions 14e and 14f for supporting the conductor 13b. Since there is a region where electron emission can occur, the surface of the conductor 13b is covered with an insulator 19. Then, a portion where the ground portion 20 is exposed, which is not covered by the insulator 19, is formed in a portion of the conductor 13b near the supporting portions 14e and 14f where the electric field is highest, in the circumferential direction.

According to the switching device formed as in the second embodiment, as in the first embodiment, electrons are emitted from the ground portion, and the DC voltage generated during the switching operation is attenuated. Can be. Therefore, the same effect as in the first embodiment can be obtained.

In each of the above embodiments, the case where the disconnecting switch is used as the switching device has been described. However, the present invention is not limited to this, and the same effect can be obtained with a circuit breaker or a grounding device. It goes without saying that it can be done.

In each of the above embodiments, the case where the conductor has a single phase has been described. However, a multi-phase switch, for example, a three-phase switchgear can also be implemented. Needless to say, it works.

[0032]

As described above, according to the first aspect of the present invention, a metal container whose inside is filled with an insulating gas at a predetermined pressure or whose inside is a vacuum, and disposed inside the metal container. It is provided with a plurality of conductors to which a voltage is applied, and an opening / closing unit for bringing and closing each conductor, and in each of the conductors, a region where electron emission of a predetermined amount or more can occur when a voltage is applied as it is,
In a switchgear in which electron emission is prevented by covering the surface of each conductor with an insulator, a portion where the ground portion of a conductor where there is no insulator is exposed on a part of the surface of the conductor. Therefore, it is possible to provide a switchgear capable of emitting electrons in the background portion and rapidly attenuating the DC voltage generated during the switching operation.

According to the second aspect of the present invention, in the first aspect, since the electric field on the conductor surface becomes the same in the portion of the background portion of the conductor, electron emission occurs in the entire region of the background portion. In addition, it is possible to provide a switchgear capable of efficiently and quickly attenuating a DC voltage generated during the switching operation.

According to a third aspect of the present invention, in the first or second aspect, the ground portion of the conductor is formed so as to include the highest electric field in the conductor. In this case, the electron emission amount becomes maximum, and it is possible to provide a switching device capable of attenuating the DC voltage generated during the switching operation more quickly.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a switchgear according to Embodiment 1 of the present invention.

FIG. 2 shows the switchgear shown in FIG.
FIG. 3 is a diagram illustrating a configuration as viewed from the perspective.

FIG. 3 shows the opening and closing device shown in FIG.
FIG. 2 is a diagram showing a configuration as viewed from I.

FIG. 4 is a diagram illustrating a relationship between a dark current value and a time of the switchgear illustrated in FIG. 1;

FIG. 5 is a diagram showing a configuration of a switchgear according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a switchgear according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a conventional switching device.

FIG. 8 is a diagram for explaining the reason why the upper surface of the conductor is covered with an insulator.

FIG. 9 is a circuit diagram showing a circuit using a switching device.

FIG. 10 is a diagram for explaining a problem of a conventional switchgear.

[Explanation of symbols]

11 metal container, 12 insulating gas, 13a, 13b conductor, 14a to 14f support, 15 fixed contact,
16 movable contacts, 17a-17f shield, 1
8 Insulation rod, 19 insulation, 20 ground.

Claims (3)

[Claims] 1. A metal container in which an insulating gas is sealed at a predetermined pressure or whose inside is a vacuum, a plurality of conductors arranged in the metal container and to which a voltage is applied, and An opening / closing unit for bringing the conductor into and out of contact with each other. In a switchgear configured to prevent electron emission by covering, a portion where a ground portion of the conductor without the insulator is exposed is provided on a surface of the conductor in a part of the region. Switchgear characterized by. 2. The switchgear according to claim 1, wherein an electric field on the surface of the conductor is the same in a portion of the conductor at a ground portion. 3. The switchgear according to claim 1, wherein the ground portion of the conductor is formed so as to include the highest electric field in the conductor.