CN212810218U - Zero-arcing shield shell, zero-arcing shield structure and circuit breaker - Google Patents

Abstract

The utility model provides a zero arcing shield casing, zero arcing shield structure and circuit breaker belongs to the low-voltage apparatus field, including cavity and closure, the cavity is used for installing the arc extinction piece, and its front end, rear end are equipped with respectively admit air, the opening of giving vent to anger, regard front end, the direction of rear end of cavity as the horizontal direction, except forward direction, the closure has the fender wall in at least upper/lower, back two directions, and the fender wall is located outside the cavity and forms half-through chamber with the cavity; and the side wall of the chamber opposite to the closed part is provided with a vent hole for communicating the chamber with the semi-through cavity. The utility model discloses an use and to cover the explosion chamber gas outlet and introduce the zero arcing shield casing that carries out the arc extinguishing in the cavity and handle with it, can prevent effectively that residual arc from loss in the wiring groove, solve the technical problem that needs get rid of the residual arc in each position among the prior art from the root, effectively keep apart residual arc and binding post.

Description

Zero-arcing shield shell, zero-arcing shield structure and circuit breaker

Technical Field

The utility model relates to a low-voltage apparatus technical field especially relates to a zero arcing cover casing, zero arcing cover structure and circuit breaker.

Background

When the breaker is in short-circuit breaking, because the energy of the generated electric arc is often very large, the electric arc cannot be extinguished only by an internal arc extinguish chamber of the breaker, the residual electric arc can be sprayed to a connecting terminal along an air passage, and meanwhile, a large amount of incandescent metal particles are carried, so that the insulating property of the connecting terminal is easily damaged if the residual electric arc is not treated.

The traditional method is that a terminal cover is added, a metal grid sheet is added in the terminal cover, and the metal grid sheet is used for cutting residual electric arcs and cooling electric arcs again, so that electric arcs are extinguished.

If chinese patent No. CN201920622562.8 a moulded case circuit breaker's terminal cover, including terminal cover and circuit breaker body, the terminal cover is installed in the terminal side of circuit breaker body, it is parallelepiped and forms the opening towards the circuit breaker body, this terminal cover includes a roof that is located the top, two face-to-face parallel arrangement's side board and a back plate of keeping away from the circuit breaker body, establish the back plate venthole on the back plate, terminal cover inside forms a cavity of accepting spun gas when breaking electric current from the circuit breaker body, the cavity docks with the explosion chamber gas outlet of circuit breaker body, be provided with in the cavity and disappear free subassembly, it disappears freely to the spun gas when breaking electric current to the circuit breaker body to disappear free subassembly.

However, the traditional structure or the method for extinguishing the electric arc does not effectively isolate the residual electric arc from the wiring terminal, and meanwhile, the residual electric arc in each direction cannot be quickly removed, so that the risk of insulation fault still exists at the wiring terminal.

Disclosure of Invention

The utility model provides a be not enough to prior art, the utility model provides a zero arcing shield structure and circuit breaker thereof solves and is difficult to effectively keep apart residual arc and binding post's problem to the terminal cover that adds the metal arc-extinguish plate of eliminating electric arc among the prior art, realizes the zero arcing arc extinction, effectively reduces binding post department and receives residual arc's influence.

One of the purposes of the utility model is to provide a zero-flashover cover shell, which comprises a cavity and a closing part, wherein the cavity is used for installing an arc extinguishing part, the front end and the rear end of the cavity are respectively provided with an air inlet opening and an air outlet opening, the direction of the front end and the rear end of the cavity is taken as the horizontal direction, besides the forward direction, the closing part is provided with a blocking wall in at least one direction from top to bottom and a blocking wall in the rear direction, and the blocking wall is arranged outside the cavity and forms a semi-through cavity with the cavity; and the side wall of the chamber opposite to the closed part is provided with a vent hole for communicating the chamber with the semi-through cavity.

The chamber in the above-mentioned zero arcing casing is used for installing the arc extinction piece, the inlet opening of the front end of its chamber is used for setting up relatively with the gas outlet of explosion chamber, semi-through chamber also has opening forward simultaneously, it also sets up relatively with the gas outlet of explosion chamber, thereby block the gas outlet from the rear side blowout in semi-through chamber, but utilize the air vent, make the gas outlet of explosion chamber not directly relative with the chamber enter into the chamber through the circuitous entering in semi-through chamber, discharge from the opening that is used for giving vent to anger of the rear end of chamber after the arc extinction piece of installing in the chamber at last.

Based on this, the utility model discloses expanded the scope that zero arcing casing can cover the gas outlet of explosion chamber, made its circuit breaker casing cooperation with the structure adaptation again and used, can make and carry out arc extinction, arc extinguishing in the gas outlet department combustion gas that follows the explosion chamber all enters into zero arcing cover casing, establishes the basis for realizing zero arcing.

In order to ensure high air-passing rate between the semi-through cavity and the chamber, and facilitate the introduction of the gas with residual electric arc entering the semi-through cavity into the chamber, the zero-flashover shield shell is further arranged as follows: the vent holes are grid grooves.

For the convenience of processing, the zero-flashover shield shell is further arranged as follows: the grid groove extends to the opening at the front end of the cavity.

In order to simplify the structure of the circuit breaker shell or the terminal cover matched with the zero-flashover cover shell, the zero-flashover cover shell is further provided with the following components: the width of the blocking wall in the up/down direction of the closure is not less than 1/2 or 2/3 of the width of the side wall of the chamber parallel thereto.

For the convenience of processing and matching use, the zero-flashover shield shell is further arranged as follows: the baffle wall is a plate-shaped body which is parallel to and spaced from the side wall of the chamber.

In order to realize the tight fit when the plate-shaped body is in plug-in fit with the circuit breaker shell, the zero-flashover shield shell is further arranged as follows: the plate-shaped body is provided with a bulge for tight fit.

A second object of the utility model is to provide a zero arcing shield structure, include as before zero arcing shield casing, arc extinction piece and circuit breaker casing, be equipped with the mount pad on the circuit breaker casing, zero arcing shield install in on the mount pad. The front end of the zero-arcing shield shell is abutted against the vicinity of an arc extinguish chamber air outlet on the circuit breaker shell and matched with the circuit breaker shell to form a closed space for wrapping the arc extinguish chamber air outlet; the arc extinguishing member is fitted in a chamber of the zero-flashover cover housing.

Through the structure, the utility model discloses zero arcing shield structure makes explosion chamber gas outlet and binding post place space keep apart, and the explosion chamber gas outlet exhaust has the unable dissipation of residual arc's gas, all must get into zero arcing shield structure earlier, just can follow the opening discharge that is used for giving vent to anger of cavity after the arc extinguishing is handled. In the process, the residual electric arc can be effectively contained in the zero-arcing shield shell through the processing of the zero-arcing shield structure.

And grid bars are arranged between the grid grooves, and the grid bars can be matched with the arc extinguishing pieces to apply acting force to the arc extinguishing pieces, so that the arc extinguishing pieces are reinforced, and the stability of the matching structure of the arc extinguishing pieces and the cavity is ensured.

The zero-arcing shield structure is further arranged as follows: the arc extinguish chamber gas outlet is located the lateral wall of the wiring groove upper portion of circuit breaker casing, be equipped with on the lateral wall of wiring groove with the closure cooperation make between closure and the wiring groove form enclosure space's cooperation structure.

In order to associate the zero-flashover shield shell with the circuit breaker shell and make the structure stable, the zero-flashover shield structure is further arranged as follows: the mounting seat is an insertion groove which is arranged on the side wall of the wiring groove and is in insertion fit with the closing piece.

For improving the arc extinguishing effect, the zero-arcing cover structure is further arranged as follows: the arc extinguishing piece is a metal grid sheet formed by U-shaped superposition or V-shaped superposition.

The third object of the utility model is to provide a circuit breaker, include as before zero arcing cover structure, terminal cover, the terminal cover can be dismantled and connect on one side circuit breaker casing that has the explosion chamber gas outlet.

For further stabilizing the relation of being connected between zero flying arc cover structure and the circuit breaker casing, above-mentioned circuit breaker further sets up as follows: and the terminal cover is provided with a limiting rib which is matched with the rear end of the zero-arcing cover shell to press the terminal cover towards the gas outlet of the arc extinguish chamber of the circuit breaker shell. When the terminal cover is used for fixing the zero-arcing shield shell on the circuit breaker shell, the circuit breaker shell can be free from other fixed connection structures such as splicing, clamping and the like except for a mounting seat used for limiting the zero-arcing shield shell relative to the gas outlet of the arc extinguish chamber, so that the structures of the circuit breaker shell and the zero-arcing shield shell are simplified, the cost is reduced, and the production efficiency is improved.

In order to adapt to different use occasions, the circuit breaker is further provided with the following components: the terminal cover is any one of a long terminal cover and a short terminal cover.

For improving the leakproofness of circuit breaker, reinforcing its safety in utilization performance, above-mentioned circuit breaker further sets up as follows: the bottom of the long terminal cover is matched with a bottom plate, and the bottom plate is connected with the long terminal cover in an inserting or clamping mode.

The utility model has the advantages as follows:

the utility model discloses a set up zero arcing shield structure in explosion chamber gas outlet department, form relative confined space in explosion chamber gas outlet department to make the terminal cover of zero arcing shield casing and circuit breaker keep apart relatively, will lock in the gas that has residual electric arc from explosion chamber gas outlet department exhaust and carry out the arc extinguishing processing in zero arcing shield structure, can suppress residual electric arc in zero arcing shield casing effectively through the metal grid piece. And the residual electric arc is prevented from dissipating to the periphery of the wiring terminal from the outlet, so that the residual electric arc is effectively isolated from the wiring terminal. Through U type stack or V type superimposed metal mesh piece, can get rid of residual electric arc fast, realize zero flashover in the true sense, greatly reduced binding post department's insulation fault risk.

Two, the utility model discloses a can form enclosure space's zero arcing cover structure with the cooperation of arc extinguishing gas outlet and realize, used zero arcing cover shell structure is simple, can realize the cooperation with the circuit breaker casing through mount pad or the mode of pegging graft, very be convenient for production and assembly.

Three, the utility model discloses used U type stack or superimposed metal grid piece independence of V type and modularization, the assembly is accomplished promptly in the cavity of disect insertion zero arcing cover casing, convenient assembling, arc extinguishing are respond well.

Four, the utility model discloses used zero arcing shield casing had both realized covering the explosion chamber gas outlet comprehensively through the half logical chamber with the cavity intercommunication, also made the volume of arc extinguishing piece, structure can realize miniaturization, miniaturization when having the arc extinguishing effect concurrently, so be suitable for the wiring groove in the installation use, still reducible cost, benefit improve.

Drawings

Fig. 1 is a schematic view of the overall structure of embodiment 1 of the present invention.

Fig. 2 is a schematic view of the overall structure of embodiment 3 of the present invention.

Fig. 3 is a schematic structural view of an arc-extinguishing member according to embodiment 3 of the present invention.

Fig. 4 is a schematic view of the whole embodiment 4 of the present invention.

Fig. 5 is a schematic cross-sectional view of embodiment 4 of the present invention.

Fig. 6 is an overall schematic view of a long terminal cover according to embodiment 5 of the present invention.

Fig. 7 is a schematic structural view of a long terminal cover according to embodiment 5 of the present invention.

Fig. 8 is a schematic view of a bottom plate according to embodiment 6 of the present invention.

Fig. 9 is an overall schematic view of a bottom plate according to an embodiment of the present invention.

Fig. 10 is a schematic view of the long terminal cover and the bottom plate according to the embodiment of the present invention.

Reference numerals: 1-circuit breaker shell, 2-zero arcing shield structure, 3-terminal shield, 21-zero arcing shield shell, 22-arc suppression piece, 211-lower convex bag, 212-air outlet opening, 213-grid bar, 214-rear baffle wall, 215-upper baffle wall, 216-upper convex bar, 221-through hole, 222-metal grid sheet;

31-short terminal cover, 32-long terminal cover, 321-connection pre-tapping hole, 322-external thread connecting base, 323-air outlet pre-tapping hole, 324-insertion groove, 325-limiting rib, 326-middle plug, 33-bottom plate, 331-insertion groove and 332-insertion plug.

Detailed Description

Embodiment 1 as shown in fig. 1, the present embodiment provides a zero arcing shield shell 21, which includes a cavity and a sealing member, wherein the cavity is a hollow shell, and the front end and the rear end of the cavity are respectively provided with an air inlet opening and an air outlet opening. In this embodiment, the zero-flashover shield shell 21 is horizontally disposed, and the side of the chamber where the air inlet opening is located is the front end, and the side of the chamber where the air outlet opening 212 is located is the rear end. As can be seen in fig. 1, the inlet opening is open and the outlet opening 212 is a square slot. During assembly, the front end of the air inlet opening is directly opposite to the air outlet of the arc extinguish chamber on the circuit breaker shell 1, so that the air inlet opening is designed into an open structure to be directly communicated with the air outlet of the arc extinguish chamber, and residual electric arcs ejected from the air outlet of the arc extinguish chamber can quickly and directly enter the chamber. The chamber is provided with arc suppression pieces 22, and the arc suppression pieces 22 are preferably sized to the chamber volume and can be directly inserted into the chamber from an air inlet opening at the front end of the chamber.

In this embodiment, an upper baffle wall 215 is disposed in parallel on the upper side wall of the chamber, the length of the upper baffle wall 215 is adapted to the distance between the front end and the rear end of the chamber, and a rear baffle wall 214 is disposed between the upper baffle wall 215 and the rear end of the chamber for connection. Both the upper wall 215 and the rear wall 214 are planar plates parallel to and spaced from the chamber sidewall, wherein a lower protrusion (the lower convex hull 211 shown in fig. 1) may be added to the lower surface of the upper wall 215 for tight fitting and positioning. Alternatively, the upper surface of the upper wall 215 may be provided with an upper rib 216 (as shown in fig. 2) for tight fitting. The width of the rear wall 214 is adapted to the distance between the left and right sides of the chamber, so that the closing member formed by the upper wall 215 and the rear wall 214 is matched with the upper side wall of the chamber to form a semi-through cavity with three openings, namely a front opening, a left opening and a right opening.

In order to communicate the semi-through cavity with the cavity, the upper sidewall is provided with a vent hole for communicating the cavity with the semi-through cavity, in this embodiment, the vent hole is a grid groove formed by a plurality of grid bars 213 distributed at intervals. The grid groove is the bar groove, and it both can enlarge the area of intercommunication between semi-through chamber and the cavity, also can cut residual electric arc, improves the arc extinguishing effect. Furthermore, the bars 213 can be used as fixing elements, so that the arc suppression element 22 inserted therein cannot be moved freely in the chamber.

In one embodiment, the length direction of the gate groove is consistent with the front and rear directions of the chamber, and the gate groove preferably extends to the opening of the front end of the chamber.

In other embodiments, the widths of the upper and rear blocking walls 215 and 214 are not less than 1/2 or 2/3 of the width of the side wall of the chamber parallel thereto, but not less than the width thereof, and the shortage is complemented by the circuit breaker housing 1 or the terminal cover 3 with which it is mated. Of course, it inevitably complicates the circuit breaker housing 1, increasing production costs to some extent, compared to an equal-width structural design.

Or, the zero-flashover cover shell 21 shown in fig. 1 is turned over, and the closing piece, namely, the closing piece consists of a lower retaining wall and a rear retaining wall and is matched with the lower side wall of the chamber to block the air outlet of the arc extinguish chamber.

Example 2 this example differs from example 1 in that: the closing member still keeps off the wall and keeps off the wall after with in this embodiment, and the left side keeps off the wall and connects between the top of the left side wall of last fender wall and cavity, and the right side wall is connected between the top of the right side wall of last fender wall and cavity, and the front and rear end that the left side kept off wall, right fender wall extends to the front end of cavity, rear end department respectively to the formation only has an open semi-through chamber forward, and this semi-through chamber still is equipped with air vent and cavity intercommunication.

Compared with the embodiment 1, the embodiment further improves the closure of the semi-through cavity of the zero-flashover cover shell 21, and only the forward opening needs to be closed when the zero-flashover cover shell is matched with the circuit breaker shell 1, so that the zero-flashover cover is more convenient to assemble and practically use.

Embodiment 3 as shown in fig. 2, this embodiment provides a zero arcing shield structure 2, the zero arcing shield case 21, the arc extinguishing member 22 and the circuit breaker case 1 described in embodiment 1, the arc extinguishing member 22 is installed in the cavity of the zero arcing shield case 21, and the arc extinguishing member 22 is a U-shaped or V-shaped metal mesh sheet 222, which is small in size and good in arc extinguishing effect, as shown in fig. 3. The arc extinguish chamber gas outlet is located the upper portion of the wiring groove inside wall of circuit breaker casing 1, below the inside wall adjacent with the arc extinguish chamber gas outlet, the perpendicular to inside wall place plane is provided with the mount pad, zero arcing shield casing 21 is kept flat on the mount pad, be equipped with on the lateral wall of wiring groove with the cooperation of closing member make between closing member and the wiring groove form the cooperation structure of enclosure space, make zero arcing shield casing 21 and the cooperation of circuit breaker casing 1 form the enclosure space of parcel arc extinguish chamber gas outlet.

The mounting seat is a plug-in slot 324 which is arranged on the side wall of the wiring slot and is in plug-in fit with the closing piece.

Embodiment 4 this embodiment provides a circuit breaker including the zero arcing shield case 21 structure described in embodiment 3, and the circuit breaker case 1 and the terminal shield 3. The zero-flashover cover shell 21 comprises a cavity and a closing piece, the cavity is a hollow shell, and the front end and the rear end of the cavity are respectively provided with an air inlet opening and an air outlet opening. An upper blocking wall is arranged on the upper side wall of the cavity in parallel, and a rear blocking wall is arranged between the upper blocking wall and the rear end of the cavity to form a semi-through cavity with three openings, namely a front opening, a left opening and a right opening. The arc extinguish chamber gas outlet is located the upper portion of the wiring groove inside wall of the circuit breaker shell 1, a mounting seat is arranged below the inside wall adjacent to the arc extinguish chamber gas outlet and adjacent to the arc extinguish chamber gas outlet, the mounting seat is of a plate-shaped structure, and a reinforcing rib can be arranged between the bottom of the mounting seat and the inside wall of the wiring groove to support the structure of the mounting seat. The mounting seat is arranged perpendicular to the plane of the inner side wall of the wiring groove, and is arranged in the horizontal direction in fig. 4. The arc extinguishing member 22 is inserted into the zero-flashover cover case 21 from an air inlet opening at the front end of the zero-flashover cover case 21, and is laid on the mount base together with the zero-flashover cover case 21. And the terminal cover 3 is detachably connected to the side breaker shell 1, so that the wiring groove and the wiring terminal inside the wiring groove are isolated together with external connection.

In order to enable the cavity of the zero-arcing shield shell 21, the front end of the semi-through cavity and the inner side wall of the wiring groove to be tightly matched to form a closed space, and further to restrain residual electric arc escaping from the air outlet of the arc extinguish chamber in the zero-arcing shield structure 2, in the embodiment, a limiting rib 325 is arranged on the inner wall of one side, facing the circuit breaker shell 1, of the terminal shield 3 and at the position corresponding to the rear blocking wall of the zero-arcing shield shell 21, after the terminal shield 3 is assembled with the circuit breaker shell 1 in an embedded mode, the limiting rib 325 is matched with the rear blocking wall of the zero-arcing shield shell 21 to enable the zero-arcing shield shell 21 to be communicated with the arc extinguishing piece 22 and to be pressed towards the inner side wall of the wiring groove where the air outlet of the.

In the present embodiment, the terminal cover 3 may be selected from a long terminal cover 32 and a short terminal cover 31, and as shown in fig. 4, the short terminal cover 31 has a shorter length in the direction in which the zero-flashover cover housing 21 is inserted into the wire connecting slot than the long terminal cover 32, and since the short terminal cover 31 has a limited length in this direction, the gap between the bottom of the short terminal cover 31 (see the position state of the short terminal cover 31 shown in fig. 4) and the breaker housing 1 is small, and the terminal cover can be used safely even without shielding the gap.

As shown in fig. 6, 7 and 10, the length of the long terminal cover 32 is obviously longer in the direction of insertion of the zero-flashover cover housing 21 into the wiring slot, so that a large gap will exist between the bottom thereof (at the same position as the short terminal cover 31) and the circuit breaker housing 1 after assembly, and the gap causes the sealability of the circuit breaker terminal to be lowered. The long terminal cover 32 may be provided with a bottom plate 33 depending on the particular application, such as in dusty, watery environments. As shown in fig. 9, the bottom plate 33 is provided with a pair of insertion grooves 331 and insertion heads 332 which are engaged with the long terminal cover 32, and the long terminal cover 32 is provided with a plug and insertion grooves 324 which are engaged with the insertion grooves 331 and the insertion heads 332. The plug and the slot 331 are located on the partition plate between the long terminal cover 32 and the bottom plate 33, the plug slot 324 and the plug 332 are located on two sides of the inside of the long terminal cover 32 and the inside of the bottom plate 33, and the bottom plate 33 and the long terminal cover 32 are inseparable through double plug-in fit of the middle part and the two sides, so that structural stability is effectively guaranteed.

To sum up, the utility model provides a zero arcing shield casing 21, use this zero arcing shield casing 21's zero arcing shield structure 2 and use this zero arcing shield structure 2's circuit breaker, can cover the explosion chamber gas outlet and introduce the zero arcing shield casing 21 that carries out the arc extinguishing in the cavity and handle through the use, can effectively prevent residual arc loss in the wiring groove, solve the technical problem that needs get rid of the residual arc in each position among the prior art from the root, effectively keep apart residual arc and binding post, protection binding post does not receive the residual arc influence, ensure binding post's life.

Claims (14)

1. A zero-flashover shield shell is characterized in that: the arc extinguishing chamber comprises a chamber and a sealing piece, wherein the chamber is used for installing an arc extinguishing piece, the front end and the rear end of the chamber are respectively provided with an air inlet opening and an air outlet opening, the direction of the front end and the rear end of the chamber is taken as the horizontal direction, the sealing piece is provided with a blocking wall in at least the upper direction and the lower direction and a blocking wall in the rear direction except the forward direction, and the blocking walls are arranged outside the chamber and form a semi-through cavity with the chamber; and the side wall of the chamber opposite to the closed part is provided with a vent hole for communicating the chamber with the semi-through cavity.

2. The zero-flashover boot housing of claim 1, wherein: the vent holes are grid grooves.

3. The zero-flashover boot housing of claim 2, wherein: the grid groove extends to the opening at the front end of the cavity.

4. A zero-flashover dome housing as set forth in any one of claims 1-3 wherein: the width of the blocking wall in the up or down direction of the closure is not less than 1/2 or 2/3 of the width of the side wall of the chamber parallel thereto.

5. The zero-flashover boot housing of claim 4, wherein: the baffle wall is a plate-shaped body which is parallel to and spaced from the side wall of the chamber.

6. The zero-flashover boot housing of claim 5, wherein: the plate-shaped body is provided with a bulge for tight fit.

7. The utility model provides a zero arcing cover structure which characterized in that: comprising the zero-flashover cover housing, the arc extinguishing member and the circuit breaker housing of any one of claims 1 to 6, wherein the circuit breaker housing is provided with a mounting seat, and the zero-flashover cover is mounted on the mounting seat; the front end of the zero-arcing shield shell is abutted against the vicinity of an arc extinguish chamber air outlet on the circuit breaker shell and matched with the circuit breaker shell to form a closed space for wrapping the arc extinguish chamber air outlet; the arc extinguishing member is fitted in a chamber of the zero-flashover cover housing.

8. The zero arcing shield structure of claim 7, wherein: the arc extinguish chamber gas outlet is located the lateral wall of the wiring groove upper portion of circuit breaker casing, be equipped with on the lateral wall of wiring groove with the closure cooperation make between closure and the wiring groove form enclosure space's cooperation structure.

9. The zero arcing shield structure of claim 8, wherein: the mounting seat is an insertion groove which is arranged on the side wall of the wiring groove and is in insertion fit with the closing piece.

10. The zero-flashover shield structure of any one of claims 7 to 9, wherein: the arc extinguishing piece is a metal grid sheet formed by U-shaped superposition or V-shaped superposition.

11. A circuit breaker, characterized by: comprising a zero arcing shield structure according to any one of claims 8-10, a terminal shield, which is detachably connected to a side circuit breaker housing having an arc chute outlet.

12. A circuit breaker as claimed in claim 11, wherein: and the terminal cover is provided with a limiting rib which is matched with the rear end of the zero-arcing cover shell to press the terminal cover towards the gas outlet of the arc extinguish chamber of the circuit breaker shell.

13. A circuit breaker as claimed in claim 12, wherein: the terminal cover is either a long terminal cover or a short terminal cover.

14. The circuit breaker of claim 13, wherein: the bottom of the long terminal cover is matched with a bottom plate, and the bottom plate is connected with the long terminal cover in an inserting or clamping mode.

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