JP2000173418A - Vacuum load-break switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum load-break switch which can precisely and easily detect a degree of vacuum without being influenced by a noise and the like of an electric circuit under both charging and interrupting conditions of the electric circuit. SOLUTION: This device is provided with a pair of metallic gaps 101, 104 which are insulated from a pair of electrodes in a vacuum vessel 43. The device is also provided with a power source 107 which applies voltage to the pair of metal gaps 101, 104, and magnetic field generating means 105, 108 which apply magnetic field on the metal gaps 101, 104 outside the vacuum vessel 43. The device measures a degree of vacuum inside the vacuum vessel 43 by detecting a current flowing between the pair of metal gaps 101, 104.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum switchgear used in a power distribution system, and more particularly to a part for monitoring the degree of vacuum.

[0002]

2. Description of the Related Art FIG. 9 is a block diagram showing a conventional vacuum switchgear disclosed in, for example, Japanese Patent Publication No. 4-3612. In particular, here, a vacuum valve and a portion for monitoring the degree of vacuum are shown. The structure of is shown. In the figure, 1 is a vacuum valve, 2 is an arc shield, 3a and 3b are auxiliary shields, 4a and 4b are fixed conductors, 5 is an impedance voltage divider,
Reference numeral 6 denotes a capacitor voltage divider, and reference numeral 7 denotes a determination unit. Judgment unit 7
Has square wave shaping circuits 71 and 72, a pulse generating circuit 73 for a zero point shift, and a pulse width determining circuit 74. 42
a is a fixed electrode, 42b is a movable electrode, and 43 is a vacuum vessel.

Next, the operation will be described. Vacuum valve 1
Is normal, it can be considered that a capacitor is coupled between the arc shield 2 and the electric circuit, and the phase of the voltage detected by the capacitor voltage divider 6 is equal to the phase of the voltage detected by the impedance voltage divider 5. Is complete. Accordingly, in this case, since the judgment unit 7 which detects the phase difference between these outputs has no phase difference between both outputs, an output indicating that the degree of vacuum of the vacuum valve 1 is normal is generated.

On the other hand, when the degree of vacuum of the vacuum valve 1 decreases, the arc shield 2 and the electrodes 42a, 42
Discharge occurs between any part such as 42b and the auxiliary shield 3. This discharge causes resistance coupling between the arc shield 2 and the electric circuit, and causes a phase difference between the voltage detected by the impedance voltage divider 5 and the voltage detected by the capacitor voltage divider 6. Based on the occurrence of the phase difference, the determination unit 7 detects a decrease in the degree of vacuum and issues an alarm.

[0005]

Since the conventional vacuum switchgear is constructed as described above, the impedance voltage divider is directly connected to the electric circuit, and the capacitor voltage divider is connected to the arc shield of the vacuum valve. However, there is a problem in that it may be directly affected by noise of the electric circuit and may be a cause of reducing the reliability of the electric circuit.

Further, since a voltage detected by an impedance voltage divider connected between the power supply side electric circuit and the ground is used to check the phase difference, the degree of vacuum is reduced only when a voltage is always applied to the electric circuit. However, in this method, since the capacitor voltage divider is connected between the arc shield and the ground, the method cannot be used unless a part of the arc shield is exposed to the outside.

The present invention has been made to solve such a conventional problem. The state of the electric circuit, that is, the degree of vacuum can be detected and detected regardless of whether the electric circuit is in a call or power failure state. It is an object of the present invention to provide a vacuum switchgear capable of accurately and easily detecting the degree of vacuum without being affected by noise or the like.

[0008]

According to a first aspect of the present invention, there is provided a vacuum switching device, comprising a pair of electrodes capable of opening and closing an electric circuit in a vacuum container, and a conductor for guiding a current to these electrodes from outside the vacuum container. In a vacuum opening and closing device in which a part of the vacuum container is made of an insulator to electrically insulate the pair of electrodes, the vacuum container is provided in the vacuum container so as to be insulated from the pair of electrodes. A pair of metal gaps, a power supply provided outside the vacuum vessel and applying a voltage to the pair of metal gaps, and a magnetic field generating means provided outside the vacuum vessel and applying a magnetic field to the metal gaps. And detecting the current flowing between the pair of metal gaps to measure the degree of vacuum inside the vacuum vessel.

In a second aspect of the present invention, the vacuum container includes a metal container in which a part of the vacuum container is insulated from the pair of electrodes, and the metal container is grounded.

According to a third aspect of the present invention, there is provided a vacuum switching device wherein the pair of metal gaps are coaxial.

[0011] A vacuum switchgear according to a fourth aspect of the present invention is configured such that the pair of metal gaps are opposed in parallel.

According to a fifth aspect of the present invention, there is provided a vacuum switching device including display means for displaying a degree of vacuum in accordance with a current value flowing through the pair of metal gaps.

According to a sixth aspect of the present invention, in the vacuum switchgear, the display means displays a state related to the degree of vacuum of the vacuum vessel in two or more stages.

According to a seventh aspect of the present invention, in the vacuum switchgear, the magnetic field generating means and a terminal for applying a voltage from a power supply to the pair of metal gaps are formed into a connector having an integral structure.

In a vacuum switchgear according to an eighth aspect of the present invention, the magnetic field generating means comprises a coil and a power supply for supplying a current for generating a magnetic field to the coil.

According to a ninth aspect of the present invention, in the vacuum switchgear, the magnetic field generating means is constituted by a permanent magnet.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. Embodiment 1 FIG. FIG. 1 is a configuration diagram showing a vacuum switching device according to Embodiment 1 of the present invention. In the figure, 1 is a vacuum valve, 2 is an arc shield, 43 is a vacuum vessel made of an insulating material such as ceramic, 106 is a hole provided in the vacuum vessel 43, 101 is a metal pipe joined to the hole 106, 102 Is an insulating cylinder joined to the metal pipe 101, 1
03 is a metal flange joined to the insulating cylinder 102, 104
Is a metal rod joined to the metal flange 103 and passing through the approximate center of the metal pipe 101.

105 is a metal rod 104 and a pipe 101
Coil 107 for applying a magnetic field to the gap formed by
Is a high-voltage power supply for applying a voltage between the pipe 101 and the metal rod 104; 108 is a coil power supply for supplying a current for generating a magnetic field to the coil 105;
A current measuring unit 110 for measuring a current flowing between the current measuring unit 109 and the metal rod 104; The coil 105 and the coil power supply constitute a magnetic field generating means.

Next, the operation will be described. Metal pipe 1
Since 01 is connected to the vacuum valve 1 through the hole 106, the inside of the metal pipe 101 has the same degree of vacuum as the vacuum valve 1. Metal pipe 101 and metal rod 10
4, a voltage is applied by the high-voltage power supply 107 so that the metal pipe 101 and the metal rod 104 are not broken. In FIG. 1, the metal pipe 101 is connected to the high-voltage power supply 107 so as to be on the cathode side. Metal pipe 101
The electrons extracted at this voltage by the voltage go to the metal rod 104 on the anode side, but when the vacuum degree of the vacuum valve 1 is normal, the electrons hardly collide with gas molecules and the like and reach the metal rod 104 as the anode. .

However, a coil power supply 108 is
Current is supplied from the metal pipe 1 by the coil 105.
When a magnetic field is applied between 01 and the metal rod 104, the electrons drawn from the metal pipe 101 make a spiral motion. When the size of the metal pipe 101 and the metal rod 104, the voltage value of the high voltage power supply 107, and the current value of the coil 105 are optimally selected, electrons do not reach the metal rod 104 serving as the anode, and helical motions until they collide with gas molecules. Will continue.

When the electrons collide with the gas molecules, the gas molecules are ionized, and the ions are ionized by the metal pipe 10 serving as the cathode.
1 and is measured by the current measuring unit 109 as an ion current. The ion current value measured by the current measuring unit 109 is displayed as the degree of vacuum on the vacuum degree display unit 110 by checking the relationship between the ion current value and the degree of vacuum in advance.

As described above, according to the first embodiment, it is possible to measure the degree of vacuum in the vacuum valve by applying a voltage and a magnetic field to the space formed by the metal pipe and the metal rod. Therefore, the degree of vacuum must be measured whether the vacuum circuit path is energized or power is interrupted, whether the vacuum valve contacts are open or closed, and whether or not part of the vacuum valve shield is outside or out. The effect is that you can

Embodiment 2 FIG. 2 is a block diagram showing a vacuum switchgear according to Embodiment 2 of the present invention. In the figure, the parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and the detailed description thereof will be omitted. In the present embodiment, the portion of the vacuum vessel 43 of the vacuum valve 1 made of an insulating material such as ceramic is composed of 43a and 43b.
The insulators 43a and 43 are divided into two parts.
b are connected by a metal part 43c of the vacuum vessel. This metal portion 43c is electrically grounded. A hole 106 is formed in the metal portion 43c, and the metal pipe 101 is joined to the hole 106. Other configurations are the same as those of the first embodiment.

Next, the operation will be described. The operation is the same as in the first embodiment. In the second embodiment,
This is the case where the metal part 43c of the vacuum vessel 43 is grounded. However, the metal part 43c does not necessarily need to be grounded. And vacuum display 1
It is only necessary to devise an electric circuit such as optically insulating the space between the ten circuits.

As described above, according to the second embodiment, it is possible to measure the degree of vacuum even if a part of the vacuum container of the vacuum valve is made of metal.

Third Embodiment FIG. 3 is a configuration diagram showing a vacuum switchgear according to a third embodiment of the present invention. In the figure, the parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and the detailed description thereof will be omitted. In the figure, a vacuum vessel 43 is composed of insulators 43a and 43b, and a vessel-shaped metal part 43c. The electric circuit includes the fixed conductor 4a to the fixed electrode 42a, the movable electrode 42b, the flexible conductor 46, and the second fixed conductor 47. The operation movable rod 4b is insulated from the electric circuit by the insulating rod 45. Further, the vacuum valve 1 has a ground electrode 48 capable of grounding an electric circuit.

The fixed ground electrode 48a is connected to the second fixed conductor 47
The movable ground electrode 48b is joined to a ground rod 49. The metal part 43c of the vacuum vessel 43 is grounded. A hole 106 is formed in the metal part 43c, and the metal pipe 101 is joined to this part. Metal pipe 1
The portions connected to 01 are the same as those in the first embodiment, and the description is omitted.

Next, the operation will be described. In this vacuum valve 1, a fixed electrode 42a and a movable electrode 4
2b not only cuts off the short-circuit current and opens the electric circuit, but also allows the electric circuit to be grounded by the ground electrode 48. Even when the movable ground electrode 48b is put into the fixed ground electrode 48a and all the electric circuits of the vacuum valve 1 are at the ground potential, a voltage is applied between the metal pipe 101 and the metal rod 104 by the high voltage power source 107, and the magnetic field is generated by the coil 105. By applying the voltage, it is possible to measure the degree of vacuum of the vacuum valve 1 as in the first embodiment.

As described above, according to the third embodiment, it is possible to stably measure the degree of vacuum even when the electric circuit of the vacuum valve is grounded without being different from the call state.

Fourth Embodiment FIG. 4 is a block diagram showing a vacuum switchgear according to a fourth embodiment of the present invention. Here, only a portion for measuring the degree of vacuum is shown. In the figure, the parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and the detailed description thereof will be omitted.
In the figure, a metal rod 104 penetrates into the vacuum valve from a point adjacent to the hole 106 and is inserted into the metal pipe 101 from the hole 106. As a result, the configuration is such that the insulating cylinder 102 and the metal flange 103 of the component of the first embodiment are not required. Other configurations are the same as those of the first embodiment.

The operation will be described. As in the first embodiment, a voltage is applied between the metal rod 104 and the metal pipe 101 by the high-voltage power supply 107, and a magnetic field is applied by the coil 105 so that the degree of vacuum inside the metal pipe 101, that is, inside the vacuum valve 1 is increased. Can be measured.

As described above, according to the fourth embodiment, the degree of vacuum can be measured even if the insulating cylinder and the metal flange are omitted, as compared with the first embodiment.

Fifth Embodiment FIG. 5 is a block diagram showing a vacuum switchgear according to a fifth embodiment of the present invention. Here, only a configuration for measuring the degree of vacuum is shown. In the figure, the parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and the detailed description thereof will be omitted. In the figure, a metal pipe 101 is joined to a hole 106 drilled in a vacuum vessel 43, which is an insulator part of the vacuum vessel, and an insulating cylinder 102 is joined to the metal pipe 101. The metal flange 103 is joined. The metal pipe 101 has an L-shaped conductor 11
2a, and an electrode 111a is joined to the conductor 112a.

A conductor 112b is joined to the metal flange 103, and an electrode 111b is joined to the conductor 112b. A magnetic field is applied to the gap formed by the electrodes 111a and 111b by the coil 105 as in the first embodiment. The conductor 112a and the conductor 112b are connected to the high-voltage power supply 107 shown in FIG. 1, and one of them is connected to the high-voltage power supply 107 via the current measuring unit 109.

Next, the operation will be described. Electrode 111a
Is a cathode, and the high-voltage power supply 10 is
7 (FIG. 1) will be described. Electrons drawn from the cathode-side electrode 111a are directed to the anode-side electrode 111b. However, since a magnetic field is generated by the coil 105, the electrons make a spiral motion so as to cling to the lines of magnetic force.

When there is no magnetic field, electrons reach the electrode 111b on the anode side almost without colliding with gas molecules. However, the spiral movement by the magnetic field increases the range of the electrons, and By optimizing the magnetic field strength and the voltage value applied to the electrodes 111a and 111b, it is possible to almost collide with gas molecules.
When electrons collide with gas molecules, the gas molecules are ionized,
The ions are drawn into the electrode 111a serving as a cathode and can be detected in the form of an ion current. Although the configuration and the like of the electrodes are different from those of the first embodiment, the principle is substantially the same.

As described above, according to the fifth embodiment, when it is difficult to arrange the electrodes coaxially, by arranging the electrodes to face each other, as in the first embodiment,
The degree of vacuum can be measured regardless of the state of the electric circuit of the vacuum valve.

Sixth Embodiment FIG. 6 is a configuration diagram showing a vacuum switchgear according to a sixth embodiment of the present invention. Here, only the configuration for measuring the degree of vacuum is shown. In the figure, the parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and the detailed description thereof will be omitted. In the figure, a permanent magnet 115 as a cylindrical magnetic field generating means is arranged outside a metal pipe 101,
As shown in the figure, it has an N pole and an S pole. Metal pipe 101
A magnetic field is applied by the permanent magnet 115 to the gap formed by the metal rod 104 and the metal rod 104. Metal pipe 10
1 and the metal rod 104, as in FIG.
7, connected to the current measuring unit 109 and the vacuum degree display unit 110. In the first embodiment, a power source for generating a magnetic field is required.
The use of a power supply eliminates the need for a power supply for generating a magnetic field.

Next, the operation will be described. Permanent magnet 11
5 has an N-pole and an S-pole as shown in the figure, so a magnetic field from the N-pole to the S-pole is generated inside the magnet, and when the metal pipe 101 is used as a cathode, the metal pipe 101 The electrons extracted from the gas collide with gas molecules by making a spiral motion in the same manner as in the first embodiment, and the degree of vacuum can be measured.

As described above, according to the sixth embodiment, a magnetic field can be applied to a gap formed by a metal pipe and a metal rod by a permanent magnet without using a power supply for generating a magnetic field. Can be detected. In the sixth embodiment, the permanent magnet has a cylindrical shape. However, the permanent magnet may have any shape such as a rod shape as long as a magnetic field can be applied to a gap formed by a metal pipe and a metal rod.

Seventh Embodiment FIG. 7 is a configuration diagram showing a vacuum switchgear according to a seventh embodiment of the present invention. Here, only the configuration for measuring the degree of vacuum is shown. In the figure, the parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and the detailed description thereof will be omitted. In the figure, a connector 118 made of an insulator is used.
Among them, there are a terminal 105 connected to the coil 105, the metal rod 104, a terminal 117 connected to the metal pipe 101,
A connection line 119 connecting the terminals 116 and 117 to the high-voltage power supply 107 and the current measuring unit 109 in FIG.
Is connected to the coil power supply 108.

Next, the operation will be described. When it is necessary to measure the degree of vacuum, when the connector 118 is inserted into a portion composed of the metal pipe 101, the insulating tube 102, the metal flange 103, and the metal rod 104, the terminal 116 is connected to the metal rod 104, 117 is connected to the metal pipe 101. As a result, a voltage can be applied between the metal rod 104 and the metal pipe 101 from the high-voltage power supply 107 (FIG. 1). Further, since the coil 105 is built in the connector 118, the metal pipe 1
01 and the metal rod 104 can apply a magnetic field to the gap, which can be electromagnetically the same as the first embodiment.

As described above, according to the seventh embodiment, it is possible to separate a portion required for measuring the degree of vacuum joined to the vacuum valve from a high-voltage power supply, a coil current source, and a measurement portion. For example, one power supply or the like is provided for a plurality of vacuum valves, and the degree of vacuum can be measured at the time of periodic inspection.

Eighth Embodiment FIG. 8 is a configuration diagram showing a vacuum switchgear according to an eighth embodiment of the present invention. Here, only the configuration for displaying the degree of vacuum is shown. For other configurations, any of Embodiments 1 to 7 above may be used. In the first to seventh embodiments, the case where the degree of vacuum is displayed from the value of the ion current is used. Since it is to determine whether the degree of vacuum is sufficient or insufficient, for example, as shown in FIG. 8C, whether the degree of vacuum is normal, caution, or abnormal may be indicated by a lamp or the like. As shown in FIGS. 8A and 8B, a portion displaying the degree of vacuum itself and a normal / abnormal display of the degree of vacuum may be displayed in combination.

In FIGS. 8A and 8B, the degree of vacuum is displayed in an analog system and a digital system, respectively. Although FIG. 8C shows three levels of normal, caution, and abnormality, two levels of normal and abnormal, or a more detailed display may be used.

As described above, according to the eighth embodiment, there is no need for the inspector to judge whether the condition is normal or abnormal based on the degree of vacuum. I can understand.

[0047]

As described above, according to the first aspect of the present invention, a pair of electrodes capable of opening and closing an electric circuit and a conductor for conducting a current to the electrodes from outside the vacuum vessel are provided in the vacuum vessel. In a vacuum opening and closing device in which a part of the vacuum vessel is made of an insulator to electrically insulate the pair of electrodes, the vacuum vessel is provided insulated from the pair of electrodes in the vacuum vessel. A pair of metal gaps, provided outside the vacuum vessel, a power supply for applying a voltage to the pair of metal gaps, and a magnetic field generating means provided outside the vacuum vessel and applying a magnetic field to the metal gaps, Since the current flowing between the pair of metal gaps is detected to measure the degree of vacuum inside the vacuum vessel, the degree of vacuum can be measured whenever necessary regardless of the state of the electric circuit of the vacuum valve, and Electrical circuit There is an effect that accurately and conveniently vacuum unaffected like noise can be measured.

According to the second aspect of the present invention, a part of the vacuum container is formed of a metal container insulated from the pair of electrodes, and the metal container is grounded. Even when a part of the metal gap is made of metal and grounded, one of the electrodes of the metal gap insulated from the electric path for measuring the degree of vacuum is at the same potential as the grounded metal part of the vacuum vessel. And the degree of vacuum can be measured irrespective of the state of the electric circuit of the vacuum valve.

According to the third aspect of the present invention, since the pair of metal gaps as electrodes are coaxial, there is an effect that the degree of vacuum can be detected stably.

According to the fourth aspect of the present invention, since the pair of metal gaps are opposed to each other in parallel, even when the metal gap cannot be made coaxial due to the structure of the device, the metal gap is stable as in the case of the coaxial shape. There is an effect that the degree of vacuum can be detected.

According to the fifth aspect of the present invention, since the display means for displaying the degree of vacuum according to the value of the current flowing through the pair of metal gaps is provided, the degree of vacuum can be determined immediately when measuring the degree of vacuum. effective.

According to the sixth aspect of the present invention, the display means displays the state related to the degree of vacuum of the vacuum vessel in two or more stages, so that the degree of vacuum can be changed according to the current value flowing through the metal gap. It is possible to intuitively judge whether the function is normal or abnormal from the viewpoint of the degree of vacuum of the vacuum valve at the time of measurement.

According to the seventh aspect of the present invention, the magnetic field generating means and the terminal for applying a voltage from a power supply to the pair of metal gaps are formed into an integral connector, so that the degree of vacuum is measured. It is only necessary to connect the power supply and the measurement unit only when the measurement is performed, and there is an effect that the measurement can be performed efficiently.

According to the eighth aspect of the present invention, since the magnetic field generating means is constituted by the coil and the power supply for supplying a current for generating a magnetic field to the coil, the magnetic field applied to the metal gap is controlled by the coil. By controlling the value of the current generated in the coil and controlling the current flowing through the coil, it is possible to generate an optimum magnetic field strength for measuring the degree of vacuum, thereby improving the sensitivity of the degree of vacuum measurement.

According to the ninth aspect of the present invention, since the magnetic field generating means is constituted by a permanent magnet, the magnetic field applied to the metal gap is generated by the permanent magnet.
This has the effect of eliminating the need for a dedicated power supply for generating a magnetic field.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a vacuum switching device according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram illustrating a vacuum switching device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a vacuum switching device according to Embodiment 3 of the present invention.

FIG. 4 is a configuration diagram showing a vacuum switching device according to a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram showing a vacuum switching device according to a fifth embodiment of the present invention.

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

FIG. 7 is a configuration diagram illustrating a vacuum switchgear according to a seventh embodiment of the present invention;

FIG. 8 is a diagram for explaining a vacuum switching device according to an eighth embodiment of the present invention.

FIG. 9 is a configuration diagram showing a conventional vacuum switching device.

[Explanation of symbols]

1 vacuum valve, 2 arc shield, 43 vacuum vessel, 45 insulating rod, 46 flexible conductor, 47
2nd fixed conductor, 48 ground electrode, 49 ground rod, 101 metal pipe, 102 insulating cylinder, 10
3 Metal flange, 104 Metal flange, 105
Coil, 106 hole, 107 high voltage power supply, 10
8 coil power supply, 109 current measurement unit, 110 vacuum degree display unit, 111 electrode, 112 conductor, 115
Permanent magnet, 116 terminals, 117 terminals, 118
Connector, 119 connection lines, 120 connection lines.

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Atsushi Sawada 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) in Mitsubishi Electric Corporation 5G026 KA01

Claims (9)

[Claims] A vacuum vessel has a pair of electrodes capable of opening and closing an electric circuit, and a conductor for conducting a current to the electrodes from outside of the vacuum vessel, and electrically insulates the pair of electrodes. In a vacuum opening and closing device in which a part of the vacuum container is formed of an insulator, a pair of metal gaps provided insulated from the pair of electrodes in the vacuum container, and a pair of metal gaps provided outside the vacuum container, A power supply for applying a voltage to the pair of metal gaps; and a magnetic field generating means provided outside the vacuum vessel and applying a magnetic field to the metal gap. A vacuum switchgear, characterized in that the degree of vacuum inside the container is measured. 2. The vacuum switching device according to claim 1, wherein a part of the vacuum container is formed of a metal container insulated from the pair of electrodes, and the metal container is grounded. 3. The vacuum switching device according to claim 1, wherein the pair of metal gaps are coaxial. 4. The vacuum switching device according to claim 1, wherein the pair of metal gaps are configured to face each other in parallel. 5. The vacuum switching device according to claim 1, further comprising display means for displaying a degree of vacuum according to a current value flowing through the pair of metal gaps. 6. The vacuum switching device according to claim 5, wherein the display means displays a state related to the degree of vacuum of the vacuum container in two or more stages. 7. The connector according to claim 1, wherein said magnetic field generating means and a terminal for applying a voltage from a power supply to said pair of metal gaps are formed into an integral connector.
The vacuum switchgear according to any one of the above. 8. The vacuum switching system according to claim 1, wherein said magnetic field generating means comprises a coil and a power supply for supplying a current for generating a magnetic field to said coil. apparatus. 9. The vacuum switching device according to claim 1, wherein said magnetic field generating means is constituted by a permanent magnet.