CN211126784U - Gas insulation switch equipment - Google Patents

Abstract

The utility model discloses a gas insulation switchgear, be in including fixing base and setting switch room, mechanism room and the secondary wiring room of fixing base top, be provided with switch module in the switch room, switch module includes the frame of integral type, the frame is from last to installing circuit breaker switch and isolation earthing switch down in proper order. Through with circuit breaker switch and isolation earthing switch integration on the integral type frame, when assembling switch module in the equipment box, need not to assemble each part one by one, reduce the volume, be favorable to the factory stock and simplify the assembly flow.

Description

Gas insulation switch equipment

Technical Field

The utility model relates to a looped netowrk cabinet technical field especially relates to a gas insulated switchgear.

Background

With the rapid development of national economy, the dependence degree of various industries on electric energy is higher and higher, so that the reliability requirement of users in the power industry on switch equipment is higher and higher. Under the background of the national advocated maintenance-free and miniaturization, the ring main unit with simple structure, miniaturization and reliable operation, especially the gas insulated switchgear, becomes a new research project which is disputed in the industry. The gas insulated switchgear among the prior art is bulky, the structure is heavy, need assemble the cabinet body with breaker switch and isolation earthing switch's part one by one, the assembly is difficult, and the operating device of inside circuit breaker adopts spring operating device or permanent magnetism operating device more, spring operating device part is up to 200 surplus money, all need guarantee relative accurate position between every part, especially for the switch guarantees to close the position, the semi-axis of reposition of redundant personnel, processing or assembly error are slightly big, then can cause the condition that the mechanism can not move, so there is higher instability in this type of mechanism, the fault incidence is high. The conventional permanent magnet mechanism generally uses a permanent magnet as a static iron core, reverse current is required to be applied to a coil in the switching-off process to generate a reverse magnetic field, the switching-off is carried out by relying on an over travel spring and a switching-off spring pushing mechanism after the switching-off, in the process, the reverse magnetic field can demagnetize the static iron core made of the permanent magnet, the Curie temperature of the permanent magnet is lower, when the ambient temperature rises, the demagnetization effect can be generated on the permanent magnet, and therefore the potential safety hazard exists in the permanent magnet mechanism by using the permanent magnet as the static iron core.

SUMMERY OF THE UTILITY MODEL

The utility model discloses aim at solving one of the technical problem that exists among the prior art at least. Therefore, the utility model provides a gas insulated switchgear, it is small, the assembly is simple.

The utility model discloses gas insulation switchgear, be in including fixing base and setting switch room, mechanism room and the secondary wiring room of fixing base top, be provided with switch module in the switch room, switch module includes the frame of integral type, the frame is from last to installing circuit breaker switch and isolation earthing switch down in proper order.

According to the utility model discloses gas insulated switchgear has following beneficial effect at least: through with circuit breaker switch and isolation earthing switch integration on the integral type frame, reduce the volume, when assembling switch module in the equipment box, need not to assemble each part one by one, only need assemble circuit breaker switch and isolation earthing switch on the frame, again with the frame installation can, be favorable to the factory stock and simplify the assembly flow.

According to the utility model discloses a gas insulated switchgear of embodiment, circuit breaker includes the base and sets up insulating cylinder on the base, be equipped with the cavity in the insulating cylinder, from last to having set gradually vacuum interrupter, insulating pull rod and permanent magnetism operating device down in the cavity, permanent magnetism operating device includes that the quiet iron core that the rectangular magnetic material was made and the movable iron core that rectangular magnetic material was made, and sets up quiet iron core, movable operation coil and the elastic component between the iron core.

According to the utility model discloses a gas insulated switchgear, one side of frame sets up the fixed plate and sets up insulating support on the fixed plate, the opposite side of frame sets up the contact mounting panel, be provided with the three-phase run-on between circuit breaker switch and the isolation earthing switch, circuit breaker switch is connected to the upper end of three-phase run-on, and isolation earthing switch is connected to the lower extreme, the middle part with insulating support is fixed.

According to the utility model discloses a gas insulated switchgear of embodiment, isolation earthing switch includes ground copper bar, ground contact, first isolation contact, second isolation contact, isolation knife tackle spare, insulating boot, keeps apart ground connection operating axis and insulating support, the ground copper bar sets up on the contact mounting panel, ground contact sets up on the ground copper bar, first isolation contact is installed the lower extreme of three-phase run-on, it installs to keep apart the ground connection operating axis on the frame, the insulating boot is installed keep apart on the ground connection operating axis and can wind and keep apart the ground connection operating axis rotatory, in isolation knife tackle spare was fixed in the insulating boot, insulating support was fixed in the bottom of frame, the second is kept apart on the contact and is fixed in on the insulating support.

According to the utility model discloses a gas insulated switchgear of embodiment, ground contact, first isolation contact and second isolation contact interval set up on the circular arc with keep apart ground connection operating axis as the centre of a circle.

According to the utility model discloses a gas insulated switchgear of embodiment, insulating support includes 2 curb plates, support bottom plate and 4 median barriers, the curb plate is established respectively in support bottom plate both sides, curb plate and support bottom plate joggle, the median barrier sets up support bottom plate just is located between two curb plates, median barrier and two curb plate joggles.

According to the utility model discloses a gas insulated switchgear of embodiment, mechanism room top-down place respectively through first movable seal with the manual separating brake mechanism that circuit breaker switch connects and the isolation operating device who connects through second movable seal and isolation earthing switch.

According to the utility model discloses a gas insulated switchgear of embodiment, gas insulated switchgear width is less than or equal to 325mm, and length is less than or equal to 800 mm.

According to the utility model discloses a gas insulated switchgear of embodiment, the frame includes front bezel, back plate, fixed plate, contact mounting panel and circuit breaker mounting panel set up between front bezel and back plate, the circuit breaker mounting panel has two, divides to establish on front bezel and back plate upper portion.

According to the utility model discloses a gas insulated switchgear of embodiment still includes the gas tank, follows the gas tank vertical direction has set gradually top extension sleeve, connection copper bar, circuit breaker, isolation earthing switch, inlet wire water conservancy diversion module, ground connection water conservancy diversion module, inlet wire sleeve and relief valve, switch module upper end links to each other with top extension sleeve through connecting the copper bar, it is circular-arc along being connected the copper bar outward, the gas tank is totally closed box, the inside sulfur hexafluoride gas that fills rated pressure of gas tank, the gas tank is equipped with first through-hole relative with circuit breaker, second through-hole, barometer fixed orifices and the observation hole relative with isolation earthing switch, the gas tank bottom is equipped with ground flange and relief valve.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic structural diagram of a gas insulated switchgear according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a side surface of a gas insulated switchgear according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a switch module according to an embodiment of the present invention;

fig. 4 is a schematic structural diagram of a permanent magnet operating mechanism in an embodiment of the present invention;

fig. 5 is a schematic structural view of an insulating support in an embodiment of the present invention;

FIG. 6 is a diagram illustrating an operation state of the isolation knife assembly according to an embodiment of the present invention;

FIG. 7 is a schematic structural view of an air box according to an embodiment of the present invention;

fig. 8 is a schematic structural diagram of a frame in an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present invention, and should not be construed as limiting the present invention.

In the description of the present invention, it should be understood that the orientation or positional relationship indicated with respect to the orientation description, such as up, down, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, a plurality of means are one or more, a plurality of means are two or more, and the terms greater than, less than, exceeding, etc. are understood as not including the number, and the terms greater than, less than, within, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present invention, unless there is an explicit limitation, the words such as setting, installation, connection, etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in combination with the specific contents of the technical solution.

Referring to fig. 1, 2 and 3, a gas insulated switchgear, includes fixing base 1 and sets up switch room 2, mechanism room 3 and secondary wiring room 4 above fixing base 1, fixing base 1 divide into cable chamber 11 and pressure release chamber 12, upper portion sets up switch room 2 behind fixing base 1, be provided with switch module 24 in the switch room 2, switch module 24 includes the frame 243 of integral type, frame 243 installs circuit breaker switch 241 and isolation earthing switch 242 from last to down in proper order. Through integrating breaker switch 241 and isolation earthing switch 242 on integral type frame 243, when assembling switch module 24 in the equipment box, need not to assemble each part one by one, only need assemble breaker switch 241 and isolation earthing switch 242 on frame 243, again with frame 243 install can, be favorable to the factory stock and simplify the assembly flow.

The gas insulated switchgear still includes gas tank 21, the utility model discloses an overall structure does: the switch module 24 is arranged in the air box 21, a top expansion sleeve 22, a connecting copper bar 23, a breaker switch 241, an isolation grounding switch 242, an incoming line flow guide module 25, a grounding flow guide module 26, an incoming line sleeve 27 and a pressure release valve 28 are sequentially arranged along the vertical direction of the air box 21, the upper end of the switch module 24 is connected with the top expansion sleeve 22 through a connecting copper bar 23, the outer edge of the connecting copper bar 23 is arc-shaped, the incoming line guiding module 25 comprises an a-phase line bank 251, a B-phase line bank 252, a C-phase line bank 253 and a bushing outgoing line bank 254, the lower end of the switch module 24 is connected with the incoming line casing 27 through the incoming line guide module 25, the grounding guide module 26 includes a grounding flange 261, an inner grounding bar 262 of the air box and an outer grounding bar 263 of the air box, the grounding bar 262 in the air box is connected with the grounding copper bar 2421 of the isolation grounding switch 242 to form a complete grounding system. The secondary wiring chamber 4 is arranged at the front part of the air box 21 and the upper part of the mechanism chamber 3, and the top of the secondary wiring chamber is flush with the top of the air box 21.

Referring to fig. 7, the air box 21 is a fully-closed box body, and in a working state, sulfur hexafluoride gas with rated pressure is filled in the air box, the air box 21 is provided with a first through hole 211 opposite to the breaker switch 241, a second through hole 212 opposite to the isolation grounding switch 242, an air pressure gauge fixing hole 213 and an observation hole 214, and the bottom of the air box 21 is provided with a grounding flange 261 and a pressure release valve 28. The gas density instrument is arranged in the gas insulated switchgear, the concentration and the pressure of sulfur hexafluoride gas in the gas tank 21 can be monitored in real time, data can be transmitted to the background in real time, and a grounding and closing visual window is arranged on the shell of the gas insulated switchgear at a position corresponding to the observation hole 214.

Referring to fig. 3 and 8, the frame 243 includes a front plate 2434, a rear plate 2435, a fixing plate 2431, a contact mounting plate 2432, and a breaker mounting plate 2433, the contact mounting plate 2432 and the breaker mounting plate 2433 being disposed between the front plate 2434 and the rear plate 2435, and the breaker mounting plates 2433 being two in number, being disposed on top of the front plate 2434 and the rear plate 2435. The circuit breaker mounting plate 2433 is an axisymmetric design part, and two mounting modes of the circuit breaker mounting plate which rotates by 210 degrees are respectively mounted on the front plate 2434 and the rear plate 2435 of the frame 243, so that the design effectively reduces the types of parts of the switch module, and the parts mainly provide a supporting effect for the permanent magnet circuit breaker.

Referring to fig. 2, 3 and 4, the circuit breaker switch 241 includes a base 2411 and an insulating cylinder 2412 disposed on the base, a cavity is disposed in the insulating cylinder 2412, a vacuum arc extinguish chamber 24121, an insulating pull rod 24122 and a permanent magnetic operating mechanism 24123 are sequentially disposed in the cavity from top to bottom, the permanent magnetic operating mechanism 24123 has a simple structure and few parts, and can reduce the volume of the equipment, the permanent magnetic operating mechanism 24123 adopts a monostable permanent magnetic operating mechanism 24123, and includes a stationary core 241231 and a moving core 241232 made of a rectangular magnetic material, and an operating coil 241233 and an elastic component disposed between the stationary core 241231 and the moving core 241232, the elastic component includes an over travel spring 241234 and a separating brake spring 241235, the over travel spring 241234 is disposed at an inner ring of the separating brake spring 241235, the rectangular magnetic material can be (Mn-Mg) Fe2O4 series, (Mn-Cu) Fe2O4 series and (Mn-Ni) Fe2O4 series, and the rectangular magnetic material has an initial non-magnetic material, The movable iron core 241232 and the static iron core 241231 are in a non-magnetic state in the initial state, in the closing process, a coil is electrified to generate a magnetic field, the movable iron core 241231 and the static iron core 241231 are simultaneously magnetized, the movable iron core 241232 approaches to the static iron core 241231 to complete closing action and simultaneously compress the over travel spring 241234 and the opening spring 241235 to store energy, in the opening process, reverse current is conducted to the coil, the movable iron core 241232 and the static iron core 241231 are demagnetized until the non-magnetic state, namely, the over travel spring 241234 and the opening spring 241235 release energy to drive a mechanism to open a brake, and the circuit breaker 241 has the characteristics of initial non-magnetism, low coercive force, high remanence, high Curie temperature and the like due to the fact that magnetic materials for manufacturing the movable iron core 232 and the static iron core 241231 have the characteristics of initial non-magnetism, high coercive force, high curie temperature and the like, and is compact in; the power consumption is low, the reaction speed is high, the closing time is less than or equal to 25ms, and the opening time is less than or equal to 15 ms; the temperature of the mechanism enduring environment is more than or equal to 170 degrees, and the demagnetization and failure probability of the mechanism are extremely low.

Referring to fig. 1 to 3, a fixing plate 2431 and an insulating support 24311 disposed on the fixing plate 2431 are disposed on one side of the frame 243, and a contact mounting plate 2432 is disposed on the other side of the frame 243. Be provided with three-phase run-on 244 between circuit breaker switch 241 and the isolation earthing switch 242, three-phase run-on 244 appearance is circular-arcly, goes up to establish the limit of bending, links with permanent magnetism circuit breaker outlet terminal, and the limit of bending is established down, connects isolation earthing switch 242, and well establishing takes the chamfer fixed orifices, and the hookup with insulating support 24311 can effectively bear rated current, and short-circuit current guarantees gas insulation switchgear overall rigidity in the dynamic and thermal stability test. The isolated ground switch 242 includes a ground copper bar 2421, a ground contact 2422, a first isolated contact 2423, a second isolated contact 2424, an isolated blade assembly 2425, an insulating cover 2426, an isolated ground operating shaft 2427 and an insulating support 2428, wherein the ground copper bar 2421 and the ground contact 2422 are both disposed on the contact mounting plate 2432, the first isolated contact 2423 is mounted at the lower end of the three-phase connecting row 244, the isolated ground operating shaft 2427 is mounted on the frame 243, the insulating cover 2426 is mounted on the isolated ground operating shaft 2427 and can rotate around the isolated ground operating shaft 2427, the isolated blade assembly 2425 is fixed in the insulating cover 2426, the insulating support 2428 is fixed at the bottom of the frame 243, and the second isolated contact 2424 is fixed on the insulating support 2428. The isolation grounding operation shaft 2427 is a regular hexagonal shaft, and the manufacturing material of the isolation grounding operation shaft is insulating material, so that the high-potential isolation knife assembly 2425 can be effectively isolated from the ground potential box body, and an effective insulation system is established. The insulating cover 2426 is placed on the insulating grounding operation shaft 2427 through a regular hexagonal hole formed in the upper end of the insulating cover, and the insulating knife assembly 2425 is placed in the insulating cover, so that the charged body insulating knife assembly 2425 can be effectively isolated from the frame 243 due to the fact that the insulating cover is formed by injection molding of an insulating material, and the insulating strength is guaranteed. The isolation ground operation shaft 2427 may also be a square or pentagonal shaft, etc. or a cylinder, which is easily conceivable in the art as a shape to facilitate rotation, and a square hole provided on the insulation case 2426 is modified corresponding to the cross section of the isolation ground operation shaft 2427.

Referring to fig. 5, the insulating support 2428 comprises 2 side plates 24281, a support bottom plate 24282 and 4 middle partition plates 24283, wherein the side plates 24281 are respectively arranged at two sides of the support bottom plate 24282, the side plates 24281 are jogged with the support bottom plate 24282, the middle partition plates 24283 are arranged at the support bottom plate 24282 and are positioned between the two side plates 24281, and the middle partition plates 24283 are jogged with the two side plates 24281. The gas insulated switchgear is formed by splicing by applying a mortise and tenon process without connecting standard parts, so that the possibility of electric breakdown is reduced from the source, and the gas insulated switchgear is of great significance for controlling the overall partial discharge of the gas insulated switchgear.

Referring to fig. 6, the ground contacts 2422, the first isolation contacts 2423 and the second isolation contacts 2424 are spaced apart on an arc centered on an isolation ground operating axis 2427. The relative rotation angle between the grounding contact 2422, the first isolating contact 2423 and the second isolating contact 2424 is 120 degrees, the three-station mechanism is changed into a position state every time the isolating grounding operation shaft 2427 operates for 60 degrees, when two ends of the isolating knife assembly 2425 are respectively connected with the first isolating contact 2423 and the second isolating contact 2424, the switch is in an isolating and closing state, when two ends of the isolating knife assembly 2425 are not connected with any contact, the switch is in an isolating state, when two ends of the isolating knife assembly 2425 are respectively connected with the grounding contact 2422 and the second isolating contact 2424, the switch is in a grounding and closing state, the isolating grounding switch 242 adopts a double-break design, the switching-on and switching-off speed can be improved, the arc pulling time of the grounding switch in a switching-on and switching-off test can be effectively reduced, and the service life of the gas insulated switchgear can be prolonged.

In some embodiments of the present invention, the mechanism chamber 3 is respectively disposed, from top to bottom, with the manual opening mechanism 311 connected to the breaker switch 241 through the first dynamic seal 312 and the isolation operation mechanism 321 connected to the isolation grounding switch through the second dynamic seal 322. The front end of the first dynamic seal 312 is directly connected with the manual opening mechanism 311 of the breaker switch 241, the rear end is directly connected with the output shaft of the breaker switch 241, the front end of the second dynamic seal 322 is directly connected with the isolation operation mechanism 321 of the isolation grounding switch 242, and the rear end is directly connected with the isolation grounding operation shaft 2427, so that the two parts are directly connected, the transmission loss is reduced, the transmission parts are reduced, the cost is reduced, and the air tightness of the air box 21 is ensured.

The gas insulated switchgear of this embodiment has adopted the design of assembling circuit breaker switch and isolation earthing switch to the frame and forming whole module to and circuit breaker switch adopts the permanent magnetism operating device that the volume is less, the part is few, and moving, the quiet iron core of permanent magnetism operating device adopts rectangular magnetic material, and mechanism's demagnetization, probability of failure are extremely low. The gas insulated switchgear has reasonable layout, the width of the gas insulated switchgear is less than or equal to 325mm, the length of the gas insulated switchgear is less than or equal to 800mm, the product size is reduced, the storage space is reduced, and the transportation cost is reduced.

Claims (10)

1. A gas-insulated switchgear device, characterized in that: including fixing base (1) and setting be in switch room (2), mechanism room (3) and secondary wiring room (4) of fixing base (1) top, be provided with switch module (24) in switch room (2), switch module (24) include frame (243) of integral type, frame (243) are from last to installing circuit breaker switch (241) and isolation earthing switch (242) down in proper order.

2. A gas-insulated switchgear device as claimed in claim 1, characterized in that: breaker switch (241) include base (2411) and set up insulating cylinder (2412) on the base, be equipped with the cavity in insulating cylinder (2412), from last to having set gradually vacuum interrupter (24121), insulating pull rod (24122) and permanent magnetism operating device (24123) down in the cavity, permanent magnetism operating device (24123) include quiet iron core (241231) that the rectangular magnetic material was made and move iron core (241232) that the rectangular magnetic material was made, and set up quiet iron core (241231), move operating coil (241233) and the elastic component between iron core (241232).

3. A gas-insulated switchgear device as claimed in claim 1, characterized in that: one side of frame (243) sets up fixed plate (2431) and sets up insulating supporter (24311) on fixed plate (2431), the opposite side of frame (243) sets up contact mounting panel (2432), be provided with three-phase run-on (244) between circuit breaker switch (241) and isolation earthing switch (242), circuit breaker switch (241) is connected to the upper end of three-phase run-on (244), and isolation earthing switch (242) is connected to the lower extreme, the middle part with insulating supporter (24311) is fixed.

4. A gas-insulated switchgear device as claimed in claim 3, characterized in that: the isolation grounding switch (242) comprises a grounding copper bar (2421), a grounding contact (2422), a first isolation contact (2423), a second isolation contact (2424), an isolation knife component (2425), an insulating cover (2426), an isolation grounding operation shaft (2427) and an insulating support (2428), wherein the grounding copper bar (2421) is arranged on the contact mounting plate (2432), the grounding contact (2422) is arranged on the grounding copper bar (2421), the first isolation contact (2423) is arranged at the lower end of the three-phase connecting row (244), the isolation grounding operation shaft (2427) is arranged on the frame (243), the insulating cover (2426) is arranged on the isolation grounding operation shaft (2427) and can rotate around the isolation grounding operation shaft (2427), the isolation knife component (2425) is fixed in the insulating cover (2426), and the insulating support (2428) is fixed at the bottom of the frame (2428), the second isolation contact (2424) is fixed on an insulating support (2428).

5. A gas-insulated switchgear device as claimed in claim 4, characterized in that: the grounding contact (2422), the first isolation contact (2423) and the second isolation contact (2424) are arranged on an arc with an isolation grounding operation shaft (2427) as a circle center at intervals.

6. A gas-insulated switchgear device as claimed in claim 4 or 5, characterized in that: the insulating support (2428) comprises 2 side plates (24281), a support bottom plate (24282) and 4 middle partition plates (24283), the side plates (24281) are respectively arranged on two sides of the support bottom plate (24282), the side plates (24281) are in joggled joint with the support bottom plate (24282), the middle partition plates (24283) are arranged on the support bottom plate (24282) and located between the two side plates (24281), and the middle partition plates (24283) are in joggled joint with the two side plates (24281).

7. A gas-insulated switchgear device as claimed in claim 1, characterized in that: the mechanism chamber (3) is respectively provided with a manual brake separating mechanism (311) connected with the breaker switch (241) through a first dynamic seal (312) and an isolation operating mechanism (321) connected with the isolation grounding switch through a second dynamic seal (322) from top to bottom.

8. A gas-insulated switchgear device as claimed in claim 1 or 2, characterized in that: the width of the gas insulated switchgear is less than or equal to 325mm, and the length of the gas insulated switchgear is less than or equal to 800 mm.

9. A gas-insulated switchgear device as claimed in claim 1, characterized in that: the frame (243) comprises a front plate (2434), a rear plate (2435), a fixing plate (2431), a contact mounting plate (2432) and a breaker mounting plate (2433), wherein the contact mounting plate (2432) and the breaker mounting plate (2433) are arranged between the front plate (2434) and the rear plate (2435), and the number of the breaker mounting plates (2433) is two and is respectively arranged on the upper portions of the front plate (2434) and the rear plate (2435).

10. A gas-insulated switchgear device as claimed in claim 1, characterized in that: the device also comprises an air box (21), wherein a top expansion sleeve (22), a connecting copper bar (23), a breaker switch (241), an isolation grounding switch (242), an incoming line flow guiding module (25), a grounding flow guiding module (26), an incoming line sleeve (27) and a pressure release valve (28) are sequentially arranged along the vertical direction of the air box (21), the upper end of the switch module (24) is connected with the top expansion sleeve (22) through a connecting copper bar (23), the outer edge of the connecting copper bar (23) is arc-shaped, the air tank (21) is a totally-enclosed tank body, the gas box (21) is filled with sulfur hexafluoride gas with rated pressure, the gas box (21) is provided with a first through hole (211) opposite to the breaker switch (241), a second through hole (212) opposite to the isolation grounding switch (242), a gas pressure meter fixing hole (213) and an observation hole (214), and a grounding flange (261) and a pressure release valve (28) are arranged at the bottom of the air box (21).

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