HK1031270B - Switch gear - Google Patents

Description

Switching device

Technical Field

The present invention relates to a switchgear having a functional unit in which a main circuit switching section for establishing/disconnecting a connection between a bus-side conductor and a load-side conductor and a ground switching section for establishing/disconnecting a connection between a load-side conductor and a ground-side conductor are integrally provided.

Background

A switching device for distributing electrical energy received via a bus to various types of equipment as loads or to another electrical room has a grounded metal housing. The metal housing can accommodate a bus side conductor for establishing a connection with a bus; a connection conductor such as a load-side conductor for establishing connection of a transmission cable for transmitting electric power to a load; a main circuit switch for establishing/disconnecting a connection between the bus side conductor and the load side conductor; a grounding switch for grounding the load side conductor; and a control device for monitoring purposes.

Such a switch device is described in japanese patent laid-open No. 28488/1995. The switching device has a function unit integrally including a main circuit switch and a ground switch, and a part of a connection conductor. The functional unit is housed in a case and performs only an operation of establishing a connection between the bus and the transmission cable.

Fig. 13 is a plan sectional view showing the configuration of the main portion of the switchgear, and fig. 14 is an electrical connection diagram showing the main portion. As shown in fig. 13, the switchgear includes a metal case 1 filled with an insulating gas; a sleeve 2a provided to be passed through a peripheral wall surface portion of the housing 1 for connecting a transmission cable; and a sleeve 2b provided to be passed through a part of the peripheral wall surface of the housing 1 to connect the bus lines. A first switch 3, a second switch 4, a third switch 5 and a vacuum arc-extinguishing chamber 9 are also arranged in the shell 1.

The bus side branch conductor 6 connected to an external bus not shown through the bushing 2b is supported by an insulating support porcelain 11 mounted on a part of the peripheral wall of the housing 1 and is housed in the housing 1. The bus-side branch conductor 6 is connected to an intermediate conductor 60, which is fixedly supported by an insulating support porcelain 60a mounted to a part of the peripheral wall of the housing 1, by means of a switch not shown provided in the vacuum arc-extinguishing chamber 9 and the first switch 3. The conduction path is divided into two legs by the intermediate conductor 60; one branch is connected to the load side conductor 2 supported by one of the bushings 2a by means of a second switch 4, and the other branch is connected to the other load side conductor 2 supported by the other bushing 2a by means of a bus and a transmission cable. The branch lines are connected to an external transmission cable, not shown, through the load-side conductor 2.

Fig. 13 shows only a single-phase circuit. However, as shown in fig. 14, the starting apparatus can be made into a three-phase circuit. Therefore, for each phase, a circuit is provided which includes the sleeves 2a and 2b, the first switch 3, the second switch 4, and the third switch 5.

The switches 3, 4 and 5 each have a swinging electrode which can swing according to an independent operating mechanical action, not shown in the figures, transmitted by means of the insulating rod 7 and the metal rod 8. The first switch 3 performs a switching operation between a closed position, a grounding position, and a disengaged position according to the swing position of the swing electrode. In the closed position, the output of the internal switch of the vacuum quenching chamber 9 is connected to a projecting fixed electrode located at a corresponding position of the intermediate conductor 60. In the grounding position, the wobble electrode is connected to a ground conductor 10 a. The disengaged position is an intermediate position between the closed position and the grounded position, and is isolated from the fixed electrode and the ground conductor 10 a.

Also, the second switch 4 performs a switching operation among three positions by means of the swinging of a corresponding swinging electrode, using the load-side conductor 2, a projecting fixed electrode provided at a corresponding position on the intermediate conductor 60, and a ground conductor 10 b. In addition, the third switch 5 performs a switching operation in three positions by means of the swinging of a corresponding swinging electrode, using the load-side conductor 2, a projecting fixed electrode located at a corresponding position of the intermediate conductor 60, and a ground conductor 10 c.

In the switch device of the above configuration, a main circuit switch portion for establishing/breaking connection between the bus-side branch conductor 6 and the load-side conductor 2 and a ground switch portion for grounding the load-side conductor 2 are provided in the housing 1 together with the connection conductor. It is only required that the bus side branch conductor 6 be connected to the bus outside the housing 1 via the sleeve 2b, and that the load side conductor 2 be connected to the transmission cable outside the housing 1 via the sleeve 2 a.

As described above, since the case 1 is grounded in the conventional switchgear, the potential difference between the charging portions of the respective first, second, and third switches 3, 4, 5 and the case 1 becomes large, and thus a ground fault is liable to occur.

The first and second switches 3 and 4 or the first and third switches 3 and 5 are connected in series between the bus-side branch conductor 6 and the load-side conductor 2. In order to secure a sufficient space for these switches, there is a limit to miniaturizing the housing 1.

The case 1 is filled with an insulating gas. In each of the switches 3, 4, 5, it is necessary to ensure that there is an insulation distance between the three phases of the three-phase circuit, between the oscillating electrode and the ground conductor, and between the oscillating electrode, the ground conductor and the fixed electrode, which is dependent on the type of insulating gas. Therefore, the switches 3, 4, 5 become bulky, and ensuring a sufficient separation distance between the switches 3, 4, 5 imposes a limit to the miniaturization of the housing.

Each phase of the three-phase loop is provided with a vacuum arc extinguishing chamber 9. Ensuring that the vacuum quenching chamber 9 has sufficient space imposes a limit to the miniaturization of the housing 1 and increases the cost of the product.

When an arc short circuit condition occurs in the housing 1, an explosion occurs, in which the insulating gas filled in the housing container 1 becomes very hot and high in pressure for a short period of time due to the arc energy. In order to prevent the explosion from occurring, a relief portion for relieving pressure must be provided in the case 1, and the case 1 is required to have sufficient strength to withstand high pressure until the internal pressure is completely relieved. Therefore, the structure of the case 1 becomes complicated and the product cost also increases.

In addition, the present invention relates to a switching device equipped with, for example: a main circuit switch portion for establishing/breaking a connection between the bus side conductor and the load side conductor, and a ground switch portion for establishing/breaking a connection between the load side conductor and the ground side conductor.

A switchgear (with attached switchboard) for distributing electrical energy received via a bus to various load devices or another electrical room has a grounded metal housing. A main circuit switch portion which can establish/disconnect a connection between a bus-side conductor for establishing a connection with a bus and a load-side conductor for establishing a connection with a load is accommodated in the metal case; a ground switch portion for establishing/disconnecting a connection between the load-side conductor and the ground-side conductor; and is equipped with control equipment required for monitoring.

Fig. 19 is an electric circuit diagram showing an example of the switching device. The switching device includes a case 201 filled with an insulating gas, a circuit breaker 202, a first switch 203, a second switch 204, and a third switch 205.

When the receiving and converting equipment on the load side of the switchgear is to be maintained and repaired, the circuit breaker 202 is first opened, and the first switch 203, the second switch 204, and the third switch 205 are opened. The first switch 203 is then actuated to electrically connect the bus side conductor 206 to the ground conductor 208, which may then ground the bus side conductor 206. The second switch 204 and the third switch 205 are reactivated to electrically connect the load side conductor 207 to the ground conductor 208, thereby grounding the load side conductor 207. By these operations, the remaining electric charges and induced currents in the bus and the load can be grounded, and electric power can be prevented from returning from the power supply to the bus and the load again, so that worker safety can be ensured.

Fig. 20 is a front sectional view showing a main part of another conventional switchgear. A main circuit switch portion 271 and a ground switch portion 272 are provided in the metal case 221 of the switch device. The main circuit switch section 271 includes a fixed electrode 226 mounted on a fixed electrode rod 230 as a bus-side conductor, and a movable electrode 227 mounted on a movable electrode rod 231. The fixed electrode rod 230 is mounted to the case 221 and electrically isolated from the case 221 by the first metal sealing part 239, the first ceramic insulating part 222, and the second metal sealing part 243. The movable electrode rod 231 is connected to an operating rod 235 via an insulating rod 273. The operating lever 235 is connected to a driving mechanism that switches the main circuit switch portion 271 between a closed position, an interrupted (shut-off) position, and an open position. In addition, the operating rod 235 is connected to a third sealing portion 240 via a bellows 234. The third seal portion 240 is connected to the housing 221 via a second seal portion 223 and a fourth seal portion 244.

When the seal inside the casing 221 is maintained by the bellows 234, the main circuit switch portion 271 can be actuated. The insulating rod 273 includes an insulating portion 253 and a shielding portion 254 connected to both ends of the insulating portion 253. The shielding portion 254 is connected to the insulating portion 253 to relax an electric field generated in a continuous boundary between the insulating portion 253 and the shielding portion 254, thereby protecting the surface of the insulating portion 253 and protecting the insulating portion 253 and the bellows 234 from metal vapor generated from the electrodes 226 and 227 when the main circuit switching portion 271 closes or opens the conductive path. An arc shielding portion 237 is provided around the main circuit switching portion 271 and is mounted on the first insulating portion 222 to prevent metal vapor of the electrodes 226, 227 from splashing that would otherwise occur when opening/closing the conductive path. The main circuit switch portion 271 is electrically insulated from the casing 221. The first ring 247 is disposed near a brass portion between the first sealing portion 239 and the first ceramic insulating portion 222 as a charging portion. The second ring 249 is disposed in the vicinity of a brass portion between the second sealing portion 243, which is a discharge portion, and the first ceramic insulating portion 222. The third ring 250 is disposed near a brass portion between the third and fourth sealing portions 240 and 244 and the second insulating portion 223 as the charging portion. The first to third rings 247, 249 and 250 are provided to relax the electric field. Both the first ring 247 and the second ring 249 are disposed inside the first insulating portion 222 to protect the inner wall surface of the first insulating portion 222 from contamination by metal vapor. The third ring 250 is disposed inside the second insulating portion 223 to prevent the inner wall surface of the second insulating portion 223 from being contaminated by metal vapor.

The grounding switch portion 272 includes a fixed electrode 228 mounted on the fixed electrode rod 232 as a load-side conductor, and a movable electrode 229 mounted on the movable electrode rod 233 as a grounded ground-side conductor. The fixed electrode rod 232 is connected to the case 221 via the first sealing portion 241, the first insulating portion 224, and the second sealing portion 245. The movable electrode rod 233 is connected to the third seal portion 242 via a bellows 236. The third sealing portion 242 is connected to the vacuum housing 221 via the second insulating portion 225 and the fourth sealing portion 246.

The ground switch portion 272 may be activated when the internal seal of the vacuum housing 221 is maintained by the bellows 236. The first ring 248 is disposed near a brass portion between the first sealing portion 241, which is a charging portion, and the first ceramic insulating portion 224. The second ring 251 is disposed in the vicinity of a brass portion between the second sealing portion 245 as a charging portion and the first ceramic insulating portion 224. The third ring 252 is provided in the vicinity of a brass portion between the third sealing portion 242 and the fourth sealing portion 246 and the second insulating portion 225, which are charging portions. The first to third rings 248, 251 and 252 are provided to relax an electric field. Both the first ring 248 and the second ring 251 are disposed inside the first insulating portion 224 to protect the inner wall surface of the first insulating portion 224 from metal vapor contamination. The third ring 252 is disposed inside the second insulating portion 225 to prevent the inner wall surface of the second insulating portion 225 from being contaminated by metal vapor.

The movable electrode rod 231 of the main circuit switch portion 271 is electrically connected to the fixed electrode rod 233 of the ground switch portion 272 by an elastic conductor 238. When the main circuit switch portion 271 is closed and the ground switch portion 272 is opened, the current outputted from the bus flows to the load via the fixed electrode rod 230, the elastic conductor 238, and the fixed electrode rod 232.

The operation of the switching device having the above-described configuration will now be described.

During normal operation, the operating lever 235 is actuated in the downward direction of fig. 20, bringing the movable electrode 227 into contact with the fixed electrode 226. In addition, the movable electrode rod 233 is actuated upward, so that the movable electrode 229 can be separated from the fixed electrode 228. The electric power outputted from the bus bar flows to the loads, i.e., the loads on various devices, through the fixed electrode rod 230, the movable electrode rod 231, the elastic conductor 238, and the fixed electrode rod 232.

In servicing and repairing the apparatus, the operating lever 235 is actuated in an upward direction in fig. 20 to separate the movable electrode 227 from the fixed electrode 226 to a blocking position and then to an open position. Next, the movable electrode rod 233 shown in fig. 20 is actuated downward, thereby bringing the movable electrode 229 into contact with the fixed electrode 228. Accordingly, the grounded movable electrode rod 233 is electrically connected to the fixed electrode rod 232, and thus charges and induced currents remaining in the load can be grounded via the fixed electrode 232 and the movable electrode 233. The movable electrode 227 is separated from the fixed electrode 226 to an open position. Therefore, it is possible to prevent the power from the bus from being applied to various kinds of equipment as a load, thereby enabling a maintenance worker to safely perform maintenance.

In the switching device having the above-described configuration, the movable electrode 229 and the fixed electrode 228 of the ground switch portion 272 and the movable electrode 227 and the fixed electrode 226 of the main circuit switch portion 271 are all the same size, and thus the switching device as a whole will be bulky. The movable electrode 229 and the fixed electrode 228 of the grounding switch portion 272 are made of, for example, a Cu — W-based alloy, and thus the entire switching device is bulky and expensive.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a switching device that reduces the occurrence of ground faults by isolating a vacuum vessel from a ground potential.

It is also an object of the present invention to provide a switchgear which can be made more compact than the existing switchgear by housing the main circuit switch section and the ground switch section in one vacuum vessel.

A further object of the present invention is to provide a switching device which is simpler in construction than existing switching devices, thereby reducing the cost of the product.

It is another object of the present invention to provide a switching apparatus in which a main circuit switching part and a ground switching part are disposed in a vacuum environment, thereby preventing explosion caused when an arc short circuit occurs in one case.

Accordingly, the present invention provides a switching device, the apparatus comprising: a vacuum enclosure insulated from ground potential, the enclosure having disposed therein:

a main circuit switch portion for establishing/breaking connection between a fixed electrode connected to a bus-side conductor or a load-side conductor and a movable electrode connected to the remaining conductors; and

and a ground switch portion for establishing/breaking connection between the fixed electrode and the movable electrode, wherein the fixed electrode is connected to the load-side conductor or a ground conductor, and the movable electrode is connected to the remaining conductors.

In the switchgear of the present invention, the vacuum casing is electrically isolated from the ground potential, and the potential of the vacuum casing is equal to an intermediate potential between the potential of the charging part belonging to the main circuit switch part and the ground potential outside the vacuum casing. The potential difference between the vacuum housing and the charging portion and the potential difference between the vacuum housing and the ground potential do not increase, so that the risk of occurrence of a ground fault can be reduced.

The main circuit switch portion and the ground switch portion are both housed in a highly insulating vacuum environment, thereby reducing the required insulation distance between the components. Therefore, the switching device of the present invention can be made more compact than the existing switching devices.

Even if an arc short circuit occurs in the vacuum chamber, the vacuum chamber does not contain gas, so that the danger of explosion caused by the arc short circuit can be avoided.

Preferably, two operating portions are provided side by side within the outer peripheral surface of the vacuum casing, one of which activates the main circuit switch portion and the other of which activates the ground switch portion.

According to the switching device of the second embodiment of the present invention, the operating portion of the main circuit switching section and the operating portion of the ground circuit section are disposed close to each other, thereby facilitating interlocking between the driving mechanisms of the operating portions.

Preferably, a pair of electrodes of the main circuit switching portion are provided in an insulating material in order to electrically insulate the fixing portion of the main circuit switching portion from the vacuum casing.

In the switching device according to the present invention, the pair of electrodes of the main circuit switching section is housed in the insulating material, and thus the withstand voltage performance can be improved. Therefore, the insulating material can be made large, and the vacuum casing can be made compact, so that the product cost can be reduced.

Preferably the arc shield around the main circuit switch section electrode is electrically insulated from the vacuum housing.

In the switchgear according to the present invention, the arc shielding portion is electrically insulated from the vacuum casing. Even if discharge occurs from the electrode pair of the main circuit switching section to the arc shielding section, the high potential of the vacuum casing can be prevented from occurring, and thus the withstand voltage performance of the switching device can be improved.

Preferably, the switching device includes an insulating rod connected to a load side electrode of the main circuit switching section and including a metal shielding section for relaxing an electric field, and an elastic conductor electrically connected to a load side electrode of the main circuit switching section and a load side electrode of the earthing switch section, an outer diameter of a fixing section of the elastic conductor adjacent to the main circuit switching section being larger than an outer diameter of the insulating rod.

In the switchgear according to the present invention, the outer diameter of the elastic conductor fixing portion near the main circuit switching portion is larger than the outer diameter of the insulating rod. The fixing portion can alleviate concentration of an electric field at an end of the insulating rod shielding portion and prevent metal vapor emitted from the main circuit switching portion from sticking to a surface of an insulating material of the insulating rod.

Preferably, the insulating rod of the main circuit switching section is disposed inside an insulating material for electrically insulating the main circuit switching section from the vacuum casing, and a pair of electrodes of the earthing switch section is disposed inside an insulating material for electrically insulating the movable part of the earthing switch section from the vacuum casing.

In the switchgear of the present invention, the insulating rod and the electrode pair of the earthing switch portion are disposed inside the insulating material, and thus the withstand voltage performance can be improved to a higher degree.

Preferably, a pair of openable or closable electrodes are provided at a position of an elastic conductor that electrically connects a load side electrode of the main circuit switch portion and a load side electrode of the ground switch portion.

In the switching device according to the present invention, the bus bar can be connected to or disconnected from the load by means of the pair of electrodes being provided at any portion of the elastic conductor and at any portion of the main circuit switching section, and thus the withstand voltage performance of the switching device can be improved to a higher degree.

The present invention has been made to solve the drawbacks of the conventional switchgear, and has as its object to provide a switchgear which can be made compact and inexpensive.

Accordingly, the present invention provides a switching device in which the movable electrode and the fixed electrode of the ground switch portion are smaller than those of the main circuit switch.

The present invention also provides a switching device in which the movable electrode and the fixed electrode of the disconnection switch portion and the movable electrode and the fixed electrode of the grounding switch portion are smaller than the movable electrode and the fixed electrode of the disconnection switch portion.

Preferably, a magnetic field generating portion is provided on a back surface of the movable electrode of the earthing switch portion, and a magnetic field generating portion is provided on a back surface of the fixed electrode of the earthing switch portion. When a conductive path is closed, the magnetic field generating portion may generate a magnetic field to attract the movable electrode and the fixed electrode to each other.

Preferably, the movable electrode and the fixed electrode of the disconnection switch portion and the movable electrode and the fixed electrode of the grounding switch portion are formed in one shape and made of one material.

Preferably, the movable electrode and the fixed electrode of the main circuit switching portion are made of a material different from that of the movable electrode and the fixed electrode of the earthing switch portion.

Preferably, the movable electrode and the fixed electrode of the disconnecting switch section are made of different materials from those of the movable electrode and the fixed electrode of the disconnecting switch section and those of the grounding switch section.

Preferably, a housing means a vacuum housing.

Drawings

Fig. 1 is a front sectional view showing the structure of a main part of a switchgear according to a first embodiment of the present invention;

fig. 2 is a plan view showing the structure of the main part of the switching apparatus according to the first embodiment of the present invention;

fig. 3 is a side view showing the structure of the main part of the switchgear according to the first embodiment of the present invention;

fig. 4 is a front sectional view showing the structure of a main part of a switching apparatus according to a second embodiment of the present invention;

fig. 5 is a plan view showing the structure of a main portion of a switching apparatus according to a second embodiment;

fig. 6 is a side view showing the structure of a main part of a switching apparatus according to a second embodiment;

fig. 7 is a front sectional view showing the structure of a main part of a switching apparatus according to a third embodiment of the present invention;

fig. 8 is a side view showing the structure of a main portion of a switching apparatus according to a third embodiment;

fig. 9 is a front sectional view showing the structure of a main part of a switchgear according to a fourth embodiment of the present invention;

fig. 10 is a front sectional view showing the structure of a main part of a switchgear according to a fifth embodiment of the present invention;

fig. 11 is a front sectional view showing the structure of a main part of a switchgear according to a sixth embodiment of the present invention;

fig. 12 is a front sectional view showing the structure of a main part of a switching apparatus according to a seventh embodiment of the present invention;

fig. 13 is a plan sectional view showing the structure of a main part of a conventional switchgear; and

FIG. 14 is an electrical connection diagram of a prior art switching device;

fig. 15 is a front sectional view showing a main part of a switchgear according to an eighth embodiment of the present invention;

fig. 16 is a front sectional view showing a main part of a switchgear according to a ninth embodiment of the present invention;

fig. 17 is a front sectional view showing a main part of another conventional switchgear as an example according to a tenth embodiment of the present invention;

FIG. 18 is a perspective view showing the main part shown in FIG. 17;

FIG. 19 is an electrical circuit diagram of an example of a conventional switchgear; and

fig. 20 is a front sectional view showing a main part of another conventional switchgear.

Detailed Description

(first embodiment)

Fig. 1 is a front sectional view showing the structure of a main part of a switchgear according to a first embodiment of the present invention; FIG. 2 is a top view thereof; and figure 3 is a side view thereof.

In the drawings, reference numeral 10 denotes a vacuum housing. A main circuit switch portion 20 and a ground switch portion 30 are housed in the vacuum casing 10. The main circuit switching section 20 includes a fixed electrode 21a provided on the front end of a fixed electrode rod 21 connected to a bus line, and a movable electrode 22a provided on the front end of a movable electrode rod 22. The fixed electrode rod 21 is connected to and electrically insulated from the vacuum casing 10 via a sealing member 41a, an insulating material 51 and a sealing member 41 b. The movable electrode rod 22 is connected to an operation rod 24 in the longitudinal direction via an insulating rod 23. The operating lever 24 is connected to an operating portion 61 that switches the main circuit switching portion 20 between a closed position, an interrupting position, and a disengaged position. The operating rod 24 is connected to and electrically insulated from the vacuum housing 10 via a bellows 71, a seal 42a, an insulating material 52 and a seal 42 b. The operating lever 24 may be activated when the internal seal of the vacuum housing 10 is maintained.

The insulating rod 23 comprises a cylindrical insulating material 23a and annular metallic shield portions 23b, each of which has a U-shaped cross section when viewed in the longitudinal direction. The metallic shield portions 23b are attached to both ends of the insulating material 23 a. The shielding portion 23b is mounted on the insulating material 23a to relax an electric field generated in a connection boundary between the shielding portion 23b and the insulating material 23a, thereby protecting the surface of the insulating material 23a and protecting the insulating material 23a and the corrugated tube 71 from metal vapor generated when the main circuit switching portion 20 closes or opens the conductive path.

Around the main circuit switching section 20, there is provided a cylindrical arc shield 26 which is mounted on the vacuum casing 10 to prevent metal vapor from splashing which would otherwise occur when a conductive path is opened/closed. The ring 51a is arranged in the edge region between the seal 41a and the insulating material 51; the ring 51b is disposed in the boundary region between the insulating material 51 and the seal 41 b; and a ring 52a is disposed in the boundary region between the insulating material 52 and the seal 42 b. These rings 51a, 51b and 52a are provided to relax the electric field generated in the boundary region and to protect the inner surfaces of the insulating materials 51, 52 from contamination (which would otherwise be contaminated by metal vapor).

The ground switch portion 30 includes a fixed electrode 31a provided on a front end of a fixed electrode rod 31, and a movable electrode 32a provided on a front end of a movable electrode rod 32, both the fixed electrode rod 31 and the movable electrode rod 32 being parallel to the fixed electrode rod 21 and the movable electrode rod 22. The fixed electrode rod 31 is disposed on the same side as the position of the movable electrode 22a of the main circuit switching section 20, and the movable electrode rod 32 is disposed on the same side as the position of the fixed electrode 21a of the main circuit switching section 20. The fixed electrode rod 31 is fixed to and electrically insulated from the vacuum casing 10 by a sealing member 43a, an insulating material 53 and a sealing member 43 b. The movable rod 32 is connected to an operating portion 62 to switch the earthing switch 30. The movable electrode rod 32 is connected to and insulated from the vacuum casing 10 via a bellows 72, a seal 44a, an insulating material 54, and a seal 44 b. The movable electrode 32 is activated while the inside of the vacuum casing 10 remains sealed.

The ring 53a is disposed in the boundary region between the seal 43a and the insulating material 53; the ring 53b is disposed in a boundary region between the insulating material 53 and the seal 43 b; and ring 54a is disposed in the boundary region between insulating material 54 and seal 44 b. These rings 53a, 53b and 54b are provided to relax the electric field generated in the boundary region, and protect the inner surfaces of the insulating materials 53, 54 from contamination by metal vapor.

The movable electrode rod 22 of the main circuit switch section 20 is electrically connected to the fixed electrode rod 31 of the earthing switch section by means of a deformable elastic conductor 80. When the main circuit switch portion 20 is closed and the ground switch portion 30 is opened, a current flows between the fixed electrode pole 21 of the main circuit switch portion 20 and the fixed electrode pole 31 of the ground switch portion 30.

In the above-described switchgear, the vacuum casing 10 is not grounded, and the potential of the vacuum vessel is equal to the intermediate potential between the potential of the charging portion belonging to the main circuit switch portion 20 and the ground switch portion 30 and the ground potential outside the vacuum casing 10. The potential difference between the vacuum housing 10 and the charging portion and the potential difference between the vacuum housing 10 and the ground potential do not increase, and thus the risk due to the ground fault can be reduced.

The main circuit switching portion 20 and the ground switching portion 30 are constructed in a highly insulating vacuum environment, and thus the required insulation distance between the components can be reduced. Therefore, the switching device of the present invention can be made more compact than the existing switching devices.

Even if an arc short occurs in the vacuum housing 10, since no gas is present in the vacuum vessel 10, the risk of explosion due to the arc short can be avoided.

(second embodiment)

Fig. 4 is a front sectional view showing the structure of a main part of a switching apparatus according to a second embodiment of the present invention; FIG. 5 is a top view thereof; and figure 6 is a side view thereof.

An operating portion 61 for actuating the main circuit switch portion 20 and an operating portion 62 for actuating the ground switch portion 30 are provided in a side-by-side configuration at the outer peripheral portion of the vacuum casing 10. The operation rod 24 and the movable electrode rod 32 are parallel to each other on the same side of the vacuum casing 10, and protrude from the same side surface of the vacuum casing 10 to be connected to the respective operation portions 61, 62 arranged side by side. The fixed electrode rod 21 of the main circuit switch portion 20 and the fixed electrode rod 31 of the ground switch portion 31 are disposed side by side and are opposed to the operating rod 24 and the movable electrode 32. The fixed electrode rod 21 and the fixed electrode rod 31 protrude outside the vacuum casing 10 from the side surface opposite to the side from which the operation rod 24 and the movable electrode rod 32 protrude. On the other hand, the same components as those related to the first embodiment are given the same reference numerals, and the duplicate explanation thereof is omitted.

In the switch device having the foregoing configuration, the operating portion 61 of the main circuit switch portion 20 and the operating portion 62 of the earthing switch portion 30 are close to each other, so that interlocking between the drive mechanisms of the operating portions 61, 62 can be facilitated.

(third embodiment)

Fig. 7 is a front sectional view showing the structure of a main part of a switching device according to a third embodiment of the present invention; fig. 8 is a side view thereof.

This switchgear embodiment omits the ring 51b and the electrodes 21a, 22a of the main circuit switching section 20 and the arc shielding section 26 are all disposed inside the insulating material 51. The arc shielding portion 26 has a double structure for alleviating the electric field generated at the joint between the insulating material 51 and the sealing material 41 b. On the other hand, the same reference numerals are given to those components which are the same as those described in the second embodiment, and repeated explanation thereof is omitted.

In the switchgear having the above-described configuration, the electrodes 21a, 22a (constituting a pair) of the main circuit switching section 20 are housed in the insulating material 51, and thus the vacuum casing 10 can be made compact. When the vacuum housing 10 is formed by a press process, the depth of drawing the housing can be reduced, and thus the cost of manufacturing the vacuum housing 10 can be reduced.

(fourth embodiment)

Fig. 9 is a front sectional view showing the structure of a main part of a switchgear according to a fourth embodiment of the present invention.

A support for supporting the arc shielding portion 26 provided around the electrodes 21a, 22a of the main circuit switch portion 20 is provided around the outer peripheral surface of the arc shielding portion 26. A support member is fixed at the center of the insulating material 51 for fixing the arc shielding part 26. The arc shielding portion 26 is insulated from the vacuum housing 10. On the other hand, the same components as those described in the third embodiment are given the same reference numerals, and the repetitive explanation thereof is omitted.

In the switchgear having the above-described structure, the arc shielding portion 26 is insulated from the vacuum casing 10. Even when the electrodes 21a, 22a of the main circuit switching section 20 are discharged to the arc shielding section, the high potential of the vacuum casing 10 can be prevented from occurring, and thus the withstand voltage performance of the switching device can be improved.

The insulating material 51 may be formed of two members between which the arc shielding portion 26 may be interposed.

(fifth embodiment)

Fig. 10 is a front sectional view showing the structure of a main part of a switchgear according to a fifth embodiment of the present invention.

Plate-like ends of both ends of the elastic conductor 80 for electrically connecting the main circuit switch portion 20 and the ground switch portion 30 are each sandwiched between a pair of conductor plates 81a and 81 b. One pair of conductor plates (composed of conductor plates 81a and 81 b) is connected to the main circuit switch portion 20, and the other pair of conductor plates is connected to the ground switch portion 30. The outer diameters of the conductor plates 81a and 81b are larger than the outer diameter of the insulating rod 23. The conductor plates 81a and 81b can alleviate the electric field from being concentrated on the end of the shielding portion 23b of the insulating rod 23 and can prevent the metal vapor from sticking to the surface of the insulating material 23a of the insulating rod 23, which would otherwise occur when the main circuit switching portion 20 is opened. On the other hand, the same components as those related to those described in the third embodiment are given the same reference numerals, and the repetitive explanation thereof is omitted.

In the switching device of the above-described structure, the use of the conductor plates 81a and 81b facilitates the connection of the elastic conductor 80 to the movable electrode rod 22 and the fixed electrode rod 31, so that the assembly can be facilitated. The conductor plates 81a and 81b can relax the electric field generated on the end of the shielding portion 23b of the insulating rod 23 and prevent metal vapor from sticking to the surface of the insulating material 23a of the insulating rod 23, which may otherwise occur when the main circuit switching portion 20 is turned off, and thus can improve the withstand voltage performance of the switching device.

A metal plate having a large resistance value may be used as the conductor plate 81a or 81b to reinforce the strength of the conductor plate.

(sixth embodiment)

Fig. 11 is a front sectional view showing the structure of a main part of a switchgear according to a sixth embodiment of the present invention.

The insulating rod 23 of the main circuit switching section 20 is disposed inside the insulating material 52. Further, the electrode 31a of the ground switch portion 30 is disposed inside the insulating material 53, and the electrode 32a thereof is disposed inside the insulating material 54. On the other hand, the same components as those described in the third embodiment are given the same reference numerals, and the duplicate explanation thereof is omitted.

In the switchgear having the above configuration, in the vacuum casing 10, when the switchgear is in the energized state, the disengaged state, or the opened state, the ground potential and the charging portion facing each other are within the insulating rod 23, the insulating rod 23 is disposed inside the insulating material 52, and in the ground switch portion 30, the ground potential and the charging portion face each other, the ground switch is disposed inside the insulating material 54. Therefore, the switching device can reduce the occurrence of ground fault, and thus can improve the withstand voltage performance.

(seventh embodiment)

Fig. 12 is a front sectional view showing the structure of a main part of a switching apparatus according to a seventh embodiment of the present invention.

A switch portion 90 composed of a movable electrode 92a and a fixed electrode 91a is provided between the main circuit switch portion 20 and the ground switch portion 30. The movable electrode 92a is disposed at the front end of a movable electrode rod 92. An operating rod 94 is connected to the other end of the movable electrode rod 92 via an insulating rod 93 including an insulating material 93a and a shielding portion 93 b. The operating lever 94 is connected to an operating portion 63 to activate the switch portion 90. The operating rod 94 is connected to and electrically insulated from the vacuum housing 10 by the bellows 73, a seal 46a, the insulating material 55 and a seal 46 b. The operating lever 94 is actuated while the seal is maintained in the vacuum housing 10. The movable electrode 22 of the main circuit switching section 20 is electrically connected to the movable electrode rod 92 of the switching section 90 through an elastic conductor 80 a.

The fixed electrode 91a is provided at the front end of the fixed electrode rod 91. The other end of the fixed electrode rod 91 is mounted to and electrically insulated from the vacuum casing 10 via an insulating material 95a and an insulating support 95 including a shielding portion 95 b. The fixed electrode rod 91 of the switch portion 90 is electrically connected to the fixed electrode rod 31 of the ground switch portion 30 via a conductor 80 b. On the other hand, the same components as those described in the third embodiment are given the same reference numerals, and the repetitive description thereof will be omitted.

In the switching device having the above-described structure, the electrodes 91a and 92a of the switching section 90 and the electrodes 21a, 22a of the main circuit switching section 20 are both open when the switching device is disconnected or grounded, and thus the withstand voltage performance can be improved.

As described above in detail, in the switchgear according to the first embodiment, the vacuum enclosure is not grounded, and the potential of the vacuum enclosure is equal to the intermediate potential between the potential of the charging portion belonging to the main circuit switch portion and the ground potential outside the vacuum enclosure. The potential difference between the vacuum housing and the charging portion and the potential difference between the vacuum housing and the ground potential are not increased, and thus the risk of occurrence of a ground fault can be reduced.

The main circuit switch portion and the ground switch portion are both housed in a vacuum environment having excellent insulation, thereby reducing the required insulation distance between the components. The switching device of the invention can therefore be made more compact than existing switching devices.

Even when an arc short circuit occurs in the vacuum vessel, since there is no gas in the vacuum vessel, explosion due to the arc short circuit can be prevented.

According to the switching device of the second embodiment, the operating portion of the main circuit switch portion and the operating portion of the earthing switch portion can be disposed close to each other, so that interlocking between the drive mechanisms of the operating portions can be facilitated.

In the switching device of the third embodiment, the pair of electrodes of the main circuit switching portion is covered in the insulating material, and thus the withstand voltage performance can be improved. Thus, the insulating material can be made larger, and the vacuum housing can be made more compact. When the vacuum housing is made by a stamping process, the depth of drawing of the housing can be reduced, and thus the cost of manufacturing the vacuum housing can be reduced.

According to the switching apparatus of the fourth embodiment, the arc shielding portion is insulated from the vacuum casing. Even when discharge occurs from the main circuit switching section electrode pair to the arc shielding section, the high potential of the vacuum casing can be prevented from occurring, and thus the withstand voltage performance of the switching device can be improved.

In the switchgear according to the fifth embodiment, the outer diameter of the elastic conductor fixing portion near the main circuit switching portion is larger than the outer diameter of the insulating rod. The fixing portion can mitigate the concentration of an electric field on the end of the shielding portion of the insulating rod and can prevent metal vapor from sticking to the surface of the insulating material of the insulating rod, which may otherwise occur when the main circuit switching portion is disengaged.

In the switchgear according to the sixth embodiment, both the insulating rod and the electrode pair of the earthing switch portion are disposed inside the insulating material, and thus the withstand voltage performance can be improved to a higher degree.

In the switching device according to the seventh embodiment, by disposing the pair of electrodes on any portion of the elastic conductor and on any portion of the main circuit switching portion, the bus bar can be connected to or disconnected from a load, and thus the withstand voltage performance of the switching device can be improved to a higher degree.

The preferred embodiments of the present invention will be described below. Those components that are the same as or correspond to those in fig. 19 and 20 are given the same reference numerals, and those components will be explained with reference to the reference numerals.

(eighth embodiment)

Fig. 15 is a front sectional view showing a switching apparatus according to an eighth embodiment of the present invention. A main circuit switch portion 271 and a ground switch portion 272 are provided in the metal case 221 of the switch device. The main circuit switch section 271 includes a fixed electrode 226 mounted on the fixed electrode rod 230 of the bus-side conductor, and a movable electrode 227 mounted on the movable electrode rod 231. The fixed electrode rod 230 is mounted to and electrically insulated from the case 221 via a first metal sealing portion 239, a first ceramic insulating portion 222, and a second metal sealing portion 243. The movable electrode rod 231 is connected to a lever 235 via an insulating rod 273. The lever 235 is connected to a drive mechanism that switches the main circuit switch portion 271 between a closed position, an interrupted position, and an open position. In addition, the operating rod 235 is connected to a third sealing portion 240 via a bellows 234. The third seal portion 240 is connected to the housing 221 via a second seal portion 223 and a fourth seal portion 244.

When the seal inside the casing 221 is maintained by the bellows 234, the main circuit switch portion 271 can be activated. The insulating rod 273 includes an insulating portion 253 and shielding portions 254 mounted to both ends of the insulating portion 253. The shield portion 254 is mounted to the insulating portion 253 in order to relax an electric field generated in a connection boundary between the insulating portion 253 and the shield portion 254, protect the surface of the insulating portion 253, and protect the insulating portion 253 and the bellows 234 from metal vapor generated from the electrodes 226 and 227 when the main circuit switching portion 271 closes or opens the conductive path. An arc shielding portion 237 is provided around the main circuit switching portion 271 and is mounted on the first insulating portion 222 to prevent the electrodes 226 and 227 from being splashed by metal vapor which would otherwise occur when the conductive path is opened/closed. The main circuit switch portion 271 is insulated from the casing 221. A first ring 247 is disposed adjacent a brass portion between a first seal portion 239, which is a charging portion, and the first ceramic insulating portion 222. A second ring 249 is provided in the vicinity of a brass portion between a second sealing portion 243 as a charging portion and the first ceramic insulating portion 222. A third ring 250 is provided in the vicinity of a brass portion between the third and fourth sealing portions 240 and 244 and the second insulating portion 223 as the charging portion. The first to third rings 247, 249 and 250 are provided to relax the electric field. Both the first ring 247 and the second ring 249 are disposed inside the first insulating portion 222 to protect the inner wall surface of the first insulating portion 222 from contamination by metal vapor. The third ring 250 is disposed inside the second insulating portion 223 to protect the inner wall surface of the second insulating portion 223 from being contaminated by metal vapor.

The ground switch portion 272 includes a fixed electrode 328 mounted on the fixed electrode rod 232 as a load-side conductor and a movable electrode 329 mounted on the movable electrode rod 233 of a grounded ground-side conductor. The fixed electrode 328 and the movable electrode 329 are both smaller than the fixed electrode 226 and the movable electrode 227 of the main circuit switch section 271. The fixed electrode rod 232 is mounted to the case 221 via a first sealing portion 241, a first insulating portion 224, and a second sealing portion 245. The movable electrode rod 233 is connected to a third seal portion 242 via a bellows 236. A third sealing portion 242 is connected to the vacuum housing 221 via a second insulating portion 225 and a fourth sealing portion 246.

The ground switch portion 372 may be activated while maintaining the interior of the vacuum housing 221 sealed via the bellows 236. The first ring 248 is disposed adjacent a brass portion between the first sealing portion 241 and the first ceramic insulating portion 224 of the charging portion. A second ring 251 is disposed adjacent a brass portion between the second sealing portion 245 of the charging portion and the first ceramic insulating portion 224. Third ring 252 is disposed about a brass portion between third sealing portion 242 and fourth sealing portion 246 of the charging portion and second insulating portion 225. The first to third rings 248, 251 and 252 are provided to relax the electric field. Both the first ring 248 and the second ring 251 are disposed inside the first insulating portion 224 to protect the inner wall surface of the first insulating portion 224 from contamination by metal vapor. The third ring 252 is disposed inside the second insulating portion 225 to protect the inner wall surface thereof from being contaminated by metal vapor.

The movable electrode rod 231 of the main circuit switch portion 271 is electrically connected to the fixed electrode rod 232 of the ground switch portion 372 via an elastic conductor 238. When the main circuit switch portion 271 is closed and the ground switch portion 372 is open, the current sent by the bus flows to the load through the fixed electrode rod 230, the elastic conductor 238, and the fixed electrode rod 232.

The housing 221 is a component of a housing as are the sealing portions 222, 239, 240, 241, 242, 243, 244, 245 and 246 and the insulating portions 222, 223, 224 and 225. The housing maintains the interior vacuum environment of the switchgear.

The operation of the switching device having the above-described configuration will be described below.

During normal operation, the operation lever 235 is driven in the downward direction shown in fig. 15, thereby bringing the movable electrode 227 into contact with the fixed electrode 226. In addition, the movable electrode rod 233 is driven upward, so that the movable electrode 329 is separated from the fixed electrode 328. The electric power sent from the bus line flows to the load, for example, various kinds of load devices, via the fixed electrode rod 230, the movable electrode rod 231, the elastic conductor 238, and the fixed electrode rod 232.

When the apparatus is serviced and repaired, the operating lever 235 is driven in an upward direction as shown in fig. 15, thereby separating the movable electrode 227 from the fixed electrode 226 to a blocking position and further to an open position. Next, the movable electrode rod 233 shown in fig. 15 is driven downward, thereby bringing the movable electrode 329 into contact with the fixed electrode 328. Accordingly, the grounded movable electrode rod 233 is electrically connected to the fixed electrode rod 232, and thus charges and induced currents remaining in the load may be grounded through the fixed electrode rod 232 and the movable electrode rod 233. The movable electrode 227 is separated from the fixed electrode 226 to an open position. Therefore, the electric power from the bus can be prevented from being applied to various kinds of load devices, thereby enabling the maintenance work to be performed safely.

In the switching apparatus having the above-described configuration, the ground switch portion 372 does not require an unexpected current breaking capability or a load current switching capability, which are required in the main circuit switch portion 271.

In the eighth embodiment, in consideration of the above-described characteristics of the ground switch portion 372, both the fixed electrode 328 and the movable electrode 329 of the ground switch portion 372 are made smaller and thinner than the fixed electrode 226 and the movable electrode 227 of the main circuit switch portion 271. Therefore, the number of Cu — W matrix alloys used to manufacture the movable electrode 329 and the fixed electrode 328 can be reduced, and thus the manufacturing cost can be reduced. In addition, the grounding switch portion 372 can be made compact, which in turn can make the entire switching device compact. Both the fixed electrode 328 and the movable electrode 329 can be made compact in diameter or thickness.

As in the case of the fixed electrode 226 and the movable electrode 227 of the main circuit switch portion 271, the fixed electrode 328 and the movable electrode 329 of the ground switch portion 372 are also required. High welding resistance performance (easy to separate electrodes) and high voltage resistance performance are achieved. However, the fixed electrode 328 and the movable electrode 329 of the ground switch portion 372 are not required to have an unexpected current breaking capability or a load current switching capability. For these reasons, the fixed electrode 328 and the movable electrode 329 are both made of a Cu — W matrix alloy, in contrast to the fixed electrode 226 and the movable electrode 227 which are made of a Cu — Cr matrix alloy.

The main circuit switch portion 271 and the ground switch portion 372 are both housed in a vacuum environment having a good insulation, and thus the required insulation distance between the main circuit switch portion 271 and the ground switch portion 372 can be reduced. In addition, even if an arc short circuit occurs in the vacuum enclosure, since no gas exists in the vacuum vessel, the risk of explosion due to the arc short circuit can be avoided, thereby ensuring high safety.

Fig. 16 is a front sectional view showing a main part of a switchgear according to a ninth embodiment of the present invention. In the explanation of this embodiment and the following embodiments, only constituent members different from those described in the eighth embodiment will be described.

The housing of the present embodiment accommodates therein the following members:

a cut-off switch portion 371 which interrupts a conductive path by separating the fixed electrode rod 230 as a bus-side conductor from the fixed electrode rod 232 as a load-side conductor, and which has a movable electrode 327 and a fixed electrode 326;

a cut-off switch portion 400 electrically connected to the cut-off switch portion 371 via the elastic conductor 238, wherein the fixed electrode 326 and the movable electrode 327 are separated from each other to open a circuit, and the cut-off switch has a fixed electrode 257 and a movable electrode 258; and

a grounding switch portion 372 electrically connected to the disconnection switch portion 400 via a conductor 268 and separating the fixed electrode rod 232 from the movable electrode rod 233, the electrode rod 233 being grounded and serving as a grounding side conductor, the grounding switch portion having a fixed electrode 328 and a movable electrode 329.

The movable electrode 258 of the disconnection switch portion 400 is mounted on the front end of the movable electrode bar 275, and the fixed electrode 257 is mounted on the fixed electrode bar 274. The fixed electrode rod 274 and the fixed electrode rod 232 are electrically connected via the conductor 268. The fixed electrode rod 274 is mounted to the housing 221 via an insulating support portion 265. The insulating support portion 265 includes a cylindrical insulating portion 266, and electric field relaxation shielding portions 267 mounted to both ends of the insulating portion 266. The movable electrode rod 275 is attached to the case 221 via the same support structure as that for supporting the movable electrode rod 231 of the interruption switch portion 371. The supporting structure and its surrounding structure are the same as those of the movable electrode rod 231 for supporting the interruption switch portion 371 and its surrounding structure. Therefore, the same reference numerals are given to the structures, and explanations thereof are omitted.

The stationary electrode 257 and the movable electrode 258 of the disconnection switch portion 400 have a disconnection performance and are identical to the stationary electrode 328 and the movable electrode 329 of the grounding switch portion 372 because neither of these electrodes requires an accidental current disconnection capability or a load current switching capability. In addition, the same electrodes as the fixed electrode 328 and the movable electrode 329 of the ground switch portion 372 are used as the fixed electrode 257 and the movable electrode 258.

In the maintenance and repair of the equipment, the operation rod 235 is driven in an upward direction as shown in fig. 16, so that the movable electrode 327 can be separated from the fixed electrode 326 to an open position. The operating rod 235 connected to the movable electrode rod 275 is driven in an upward direction as shown in fig. 16, so that the movable electrode 258 of the cut-off switch portion 400 can be separated from the fixed electrode 257 to an open position. Next, the movable electrode rod 233 shown in fig. 16 is driven downward, thereby bringing the movable electrode 329 into contact with the fixed electrode 328. Accordingly, the grounded movable electrode rod 233 is electrically connected to the fixed electrode rod 232, and thus the residual charge of the load and the induced current that occurs can be grounded via the fixed electrode rod 232 and the movable electrode rod 233. In addition, the fixed electrode 230 as the bus side conductor and the fixed electrode rod 232 as the load side conductor are detached by the separation of the movable electrode 258 from the fixed electrode 257, thereby preventing the electric power from the bus from being applied to various types of load equipment and enabling a maintenance worker to perform maintenance safely.

In this embodiment, both the fixed electrode 257 and the movable electrode 258 of the cut-off switch portion 400 are open when the switching device is in an open or a grounded state. The withstand voltage performance of the switching device is achieved by a gap between the fixed electrode 326 and the movable electrode 327 of the interrupter switch portion 371 and a gap between the fixed electrode 257 and the movable electrode 258, thereby improving the withstand voltage performance of the switching device. In addition, as in the case of the fixed electrode 328 and the movable electrode 329 of the ground switch portion 372, the fixed electrode 257 and the movable electrode 258 of the disconnection switch portion 400 do not require an unexpected current disconnection capability or a load current switching capability, which is required in the disconnection circuit switch portion 371. Therefore, a general electrode may be used to form the fixed electrode 257 and the movable electrode 258 of the disconnection switch portion 400, and may also be used to ground the fixed electrode 328 and the movable electrode 329 of the switch portion 372.

(tenth embodiment)

Fig. 17 is a front sectional view showing a main part of another conventional type of switchgear according to a tenth embodiment of the present invention, and fig. 18 is a perspective view showing the main part shown in fig. 17.

In this embodiment, a magnetic field generating portion 281 is installed at the rear surface of the fixed electrode 328 of the ground switch portion 472 to generate a magnetic field in the axial direction of the fixed electrode rod 232. In addition, a magnetic field generating portion 282 is installed on the rear surface of the movable electrode 329 of the ground switch portion 472 to generate a magnetic field in the axial direction of the movable electrode rod 233.

When the ground switch portion 472 is grounded and closed, if sufficient external pressure is not applied in the direction in which the movable electrode 329 is in contact with the fixed electrode 328, repulsion between the fixed electrode 328 and the movable electrode 329 occurs after the fixed electrode 328 and the movable electrode 329 have been in contact with each other, thereby allowing a gap to be generated and an arc to be generated. This action causes the fixed electrode 328 and the movable electrode 329 to splash the metal vapor. Therefore, the areas of the fixed electrode 328 and the movable electrode 329 melted by the arc will increase. Therefore, a large moving force must be applied to the movable electrode rod 233 to open the ground switch portion 472.

In order to prevent the arc from being generated, a sufficient external pressure is necessary to prevent the generation of a gap, which would otherwise occur after the fixed electrode 328 and the movable electrode 329 have been brought into contact with each other. The increase in the external pressure involves the necessity of reinforcing the strength of the driving mechanism connected to the movable electrode rod 233, and thus increases the load of manual operation.

In the present embodiment, when the grounding switch portion 472 is grounded and closed, an electric current flows from the fixed electrode rod 232 to the movable electrode rod 233 via the grounding switch portion 472. At this time, current flows through the magnetic field generating portions 281 and 282. The fixed electrode 328 and the movable electrode 329 are attracted to each other by the magnetic field generated by the current flowing through the magnetic field generating portions 281 and 282, so that the gap can be prevented from being generated therebetween. Accordingly, it is possible to prevent the metal vapor of the fixed electrode 328 and the movable electrode 329 from splashing, which would otherwise occur by the arc action after the fixed electrode 328 and the movable electrode 329 are brought into contact with each other. In addition, the number of electrodes melted by the arc may be reduced, thereby enabling the ground switch portion 472 to be opened with a small force. As a result, the mechanism of the ground switch portion 472 can be made compact.

As described above, in the switching device of the present invention, the movable electrode and the fixed electrode of the ground switch portion are smaller than those of the main circuit switch portion. Therefore, the entire switchgear can be made compact, and the cost thereof can be reduced.

In the switching device of the present invention, the movable electrode and the fixed electrode of the disconnecting switch portion and the movable electrode and the fixed electrode of the grounding switch portion are smaller than the movable electrode and the fixed electrode of the disconnecting switch portion. Therefore, the entire switchgear can be made compact, and the cost thereof can be reduced.

In the switch device of the present invention, a magnetic field generating portion is provided on the back surface of the movable electrode of the earthing switch portion, and a magnetic field generating portion is provided on the back surface of the fixed electrode of the earthing switch portion. When the conductive path is closed, the magnetic field generating portion may generate a magnetic field to attract the movable electrode and the fixed electrode to each other. Therefore, it is possible to prevent the metal vapor of the fixed electrode and the movable electrode from splashing, which would otherwise occur due to the arc after the fixed electrode and the movable electrode are brought into contact with each other. In addition, since the number of electrodes melted by the arc is reduced, the earthing switch is partially opened with a small force. Therefore, the mechanism for actuating the earthing switch portion can be made compact.

In the switch device of the present invention, the movable and fixed electrodes of the disconnection switch portion and the movable and fixed electrodes of the grounding switch portion may be formed in one shape and made of one material. Therefore, a common electrode can be used for manufacturing the fixed electrode and the movable electrode of the interruption switch portion, and can also be used for manufacturing the fixed electrode and the movable electrode of the grounding switch portion.

In the switching device of the present invention, the material for the movable electrode and the fixed electrode of the main circuit switching portion may be selected from a variety of materials having excellent accidental current interruption performance, load current switching performance, solder resistance performance, and voltage resistance performance. The movable electrode and the fixed electrode used for the earthing switch portion may be selected from materials having soldering resistance and voltage resistance.

In the switching device of the present invention, the material for the movable electrode and the fixed electrode of the interruption switch portion may be selected from a variety of materials having excellent unexpected current interruption performance, load current switching performance, solder resistance, and voltage resistance. The materials for the movable electrode and the fixed electrode of the disconnection switch portion and the materials for the movable electrode and the fixed electrode of the grounding switch portion may be selected from materials having excellent soldering resistance and voltage resistance.

In the switchgear of the present invention, a housing is a vacuum housing. Thus, gas expansion and explosion due to short circuit of small arc can be prevented, and safety can be improved.

Claims (13)

1. A switching device, comprising:

a housing insulated from ground potential and evacuated therein, said housing having therein:

a main circuit switch portion for establishing/releasing connection between a fixed electrode connected to a bus-side conductor or a load-side conductor and a movable electrode connected to the remaining conductors; and

a grounding switch portion for establishing/breaking connection between a fixed electrode connected to the load-side conductor or the grounding conductor and a movable electrode connected to the remaining conductor.

2. The switching device according to claim 1,

two operation portions, one of which activates the main circuit switch portion and the other of which activates the ground switch portion, are provided side by side on an outer peripheral surface of the vacuum casing.

3. The switching device according to claim 1,

a pair of electrodes of the main circuit switching section is provided inside an insulating material for electrically insulating the main circuit switching section from the vacuum casing.

4. The switching device according to claim 1,

an arc shield portion disposed around the main circuit switch portion electrodes is electrically insulated from the vacuum housing.

5. The switching device of claim 1, further comprising:

an insulating rod connected to a load side electrode of the main circuit switching part and including a metal shielding part for relaxing an electric field, an

An elastic conductor electrically connected to a load side electrode of the main circuit switch portion and a load side electrode of the earthing switch portion, the elastic conductor fixing portion being located close to the main circuit switch portion and having an outer diameter larger than that of the insulating rod.

6. The switching device according to claim 5,

the insulating rod of the main circuit switch portion is disposed inside an insulating material for electrically insulating the movable portion of the main circuit switch portion from the vacuum casing, and

a pair of electrodes of the earthing switch portion is disposed inside an insulating material for electrically insulating a movable portion of the earthing switch portion from the vacuum casing.

7. The switching device according to claim 1,

a pair of openable or closable electrodes are provided at a position on an elastic conductor which can electrically connect a load side electrode of the main circuit switch portion and a load side electrode of the ground switch portion.

8. A switching device, comprising:

a housing insulated from ground potential and having a vacuum therein, the housing having: a main circuit switching section which separates a bus side conductor and a load side conductor and includes a movable electrode and a fixed electrode; and

a ground switch portion which separates a load-side conductor and a ground-side conductor from each other and has a movable electrode and a fixed electrode, wherein

The movable electrode and the fixed electrode of the ground switch portion are smaller than the movable electrode and the fixed electrode of the main circuit switch.

9. The switching device according to claim 8,

a magnetic field generating portion is provided on the back surface of the movable electrode of the earthing switch portion, and

the grounding switch part is provided with a magnetic field generating part on the back of the fixed electrode, and when a conductive channel is closed, the magnetic field generating part can generate a magnetic field to enable the movable electrode and the fixed electrode to attract each other.

10. The switching device according to claim 8,

also includes a circuit breaking switch part with a fixed electrode and a movable electrode, wherein

The fixed electrode and the movable electrode of the disconnection switch portion and the movable electrode and the fixed electrode of the grounding switch portion are made in one shape and made of one material.

11. The switching device according to claim 8,

the movable electrode and the fixed electrode of the main circuit switching portion are made of a material different from that of the movable electrode and the fixed electrode of the earthing switch portion.

12. A switching device, comprising:

a housing insulated from ground potential and evacuated therein, said housing having:

a cutoff switch portion separating a bus side conductor and a load side conductor and including a movable electrode and a fixed electrode;

a cut-off switch portion electrically connected to the cut-off switch portion and opened after the movable electrode and the fixed electrode are separated from each other, and having a movable electrode and a fixed electrode; and

a ground switch portion electrically connected to the disconnection switch portion and capable of separating the load side conductor from a grounded ground conductor and having a movable electrode and a fixed electrode, wherein

The movable electrode and the fixed electrode of the disconnection switch portion and the movable electrode and the fixed electrode of the grounding switch portion are smaller than the movable electrode and the fixed electrode of the disconnection switch portion.

13. The switching device according to claim 12,

the movable electrode and the fixed electrode of the disconnecting switch section are made of different materials from those of the movable electrode and the fixed electrode of the disconnecting switch section and those of the movable electrode and the fixed electrode of the grounding switch section.