Isolation operation interlocking structure and isolation circuit breaker

Abstract

The utility model provides an isolation operation interlocking structure and an isolation circuit breaker. The isolation operation interlocking structure comprises a middle door interlocking structure and a switch-on and switch-off interlocking structure which are arranged on two opposite sides of an operating contact during installation. The opening and closing interlocking structure and the middle door interlocking structure are correspondingly linked with the opening and closing state of the opening and closing mechanism and the opening and closing state of the middle door, and the two interlocking structures can be stopped in a direct butt joint channel of the operating contact and the isolation operating handle to prevent the isolation operating handle from entering the channel to be in butt joint with the operating contact. Or a butt joint channel can be rotationally formed to expose the operating contact, so that the handle can be inserted into the operating contact to operate the isolation function of the isolation circuit breaker, and therefore, the isolation switch is prevented from being operated when the middle door is opened and the opening and closing mechanism is closed, the isolation operation safety is improved, and the risk of electric shock is also avoided.

Description

Technical Field

[0001] This utility model relates to the field of high-voltage switchgear technology, and more specifically, to an isolation operation interlocking structure and an isolation circuit breaker. Background Technology

[0002] The longitudinal rotating isolating circuit breaker integrates a high-voltage vacuum circuit breaker and a high-voltage disconnecting switch. It uses a circuit-breaking operating mechanism to drive the moving contacts of the vacuum interrupter within the three-phase poles to open and close the circuit, and an isolating operating mechanism to achieve the isolation function by longitudinally rotating the three-phase poles. To prevent operator error and electric shock accidents, and to improve the safety of isolation operation, the longitudinal rotating isolating circuit breaker is equipped with an interlocking device. The disconnecting switch can only be operated when the intermediate door (the door corresponding to the handcart position) of the longitudinal rotating isolating circuit breaker is closed. That is, the isolating operating handle can only be inserted and connected to the operating contacts on the forward and reverse motors after the intermediate door is closed, controlling the forward and reverse motors for isolation function control. Currently, the interlocking device structure in the longitudinal rotating isolating circuit breaker is relatively complex, occupies a large installation space, and results in a large size of the switchgear. Utility Model Content

[0003] The purpose of this utility model is to provide a simple, safe and reliable isolation operation interlocking structure and an isolation circuit breaker using the same.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] This utility model provides an isolation operation interlocking structure for installation in the operating mechanism of an isolating circuit breaker, near the operating contacts of the forward and reverse motor of the operating mechanism. It includes a closing / opening interlocking structure and a middle door interlocking structure installed on opposite sides of the operating contacts during installation. The middle door interlocking structure prevents the isolating operating handle from entering the docking channel and engaging with the operating contacts when the middle door is open, and allows the docking channel to be opened by the pressure of the isolating operating handle when the middle door is closed. The closing / opening interlocking structure is linked with the closing / opening mechanism. When the closing / opening mechanism is in the closed state, it prevents the isolating operating handle from entering the docking channel and engaging with the operating contacts, and allows the docking channel to be opened by the pressure of the isolating operating handle when the closing / opening mechanism is in the open state.

[0006] In one embodiment, the middle door interlocking structure includes a first mounting base, a limiting fork, and a linkage contact rod; the first mounting base is used to be mounted on the frame of the operating mechanism; the limiting fork is rotatably mounted on the first mounting base and includes a first limiting arm, one end of which is horizontally positioned in front of the operating contact; the linkage contact rod includes a pressing rod and a pressing rod, the pressing rod abutting against the side of the first limiting arm facing the operating contact, and the pressing rod receiving the pressing action from the middle door and rotating vertically to move the pressing rod away from the rotation range of the first limiting arm.

[0007] In one embodiment, the middle door interlocking structure further includes a first tension spring, and the limiting fork includes a connecting arm that is integrally connected to the first limiting arm and defines an included angle. The first tension spring is located within the included angle and its two ends are respectively connected to the first mounting base and the connecting arm, and is used to reset the first limiting arm horizontally in front of the operating contact after the force exerted by the isolation operating handle on the first limiting arm is removed.

[0008] In one embodiment, the connecting arm is provided with a plurality of spring connecting holes along its length, and the first tension spring hook is provided on the spring connecting holes.

[0009] In one embodiment, the clamping rod is connected to one end of the pressing rod and defines an acute angle, and the width of the pressing rod gradually decreases in the direction away from the clamping rod; the linkage rod also includes a counterweight head, which is connected to the connection part of the clamping rod and the pressing rod, and the counterweight head has a pivot hole for a pivot shaft to pass through so that the linkage rod can rotate around the pivot shaft.

[0010] In one embodiment, the opening and closing interlocking structure includes a second mounting base, a limiting crank arm, and a linkage block. The second mounting base is used to fix it to the frame of the operating mechanism. The limiting crank arm includes a second limiting arm arranged in a horizontal direction and a stop arm arranged in a vertical direction and connected to one end of the second limiting arm. The second limiting arm is rotatably mounted on the second mounting base, and its end away from the stop arm is horizontally positioned in front of the operating contact. The linkage block is used to link with the opening and closing mechanism, rotatably enters the rotation path of the stop arm, and restricts the rotation of the limiting stop arm.

[0011] In one embodiment, the opening and closing interlocking structure further includes a second tension spring, which is disposed on the side of the limit arm facing the forward and reverse motor. One end of the spring is hooked on the second mounting base, and the other end is hooked on the end of the second limit arm near the stop arm. The spring is used to reset the second limit arm horizontally in front of the operating contact after the force exerted by the isolation operating handle on the second limit arm is removed.

[0012] In one embodiment, the opening and closing interlocking structure further includes a limiting post for limiting the rotation angle of the second limiting arm; the second limiting arm is provided with a shaft hole and a limiting groove, the shaft hole is located at one end of the second limiting arm near the stop arm and is used to pass through the shaft and connect to the second mounting base, the limiting groove is located on the side of the shaft hole near the stop arm and on the side of the second limiting arm facing the forward and reverse motor; the second mounting base is provided with a second mounting hole and a limiting post mounting hole corresponding to the shaft hole and the limiting groove, respectively; the limiting post is inserted into the limiting post mounting hole of the second mounting base and abuts against the inner side of the limiting groove.

[0013] In one embodiment, the opening and closing interlocking structure is configured such that the limiting crank arm rotates horizontally and the linkage block rotates vertically.

[0014] As a second aspect, the present invention also provides an isolating circuit breaker, including an operating mechanism and the aforementioned isolating operation interlocking structure. The operating mechanism includes a forward and reverse rotating motor with operating contacts, and the opening and closing interlocking structure and the middle door interlocking structure are arranged on opposite sides of the operating contacts.

[0015] The beneficial effects of the technical solution provided by this utility model are as follows: By setting up a circuit breaker interlocking structure and a middle door interlocking structure, which are linked with the circuit breaker's opening and closing state and the middle door's opening and closing state, both interlocking structures can block the operating handle from entering the channel and connecting with the operating contact in the docking channel between the operating contact and the isolating operating handle, or can rotatably allow the docking channel to be opened to expose the operating contact so that the handle can be inserted into the operating contact to operate the isolating function of the isolating circuit breaker. Thus, the operation of the isolating switch is avoided when the middle door is open and the circuit breaker is closed, which improves the safety of the isolating operation and avoids the risk of electric shock. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model, the accompanying drawings used in the description of the embodiments of this utility model will be briefly introduced below.

[0017] Figure 1 A perspective view of an isolation operation interlocking structure provided in one embodiment of this utility model;

[0018] Figure 2 A perspective view of a limiting fork provided in one embodiment of the present utility model;

[0019] Figure 3 A perspective view of a linkage contact rod provided in one embodiment of the present utility model;

[0020] Figure 4 A perspective view of a second mounting base provided in one embodiment of the present utility model;

[0021] Figure 5 A perspective view of a limiting crank arm provided in one embodiment of the present utility model;

[0022] Figure 6 A perspective view of a first mounting base provided in one embodiment of the present utility model;

[0023] Figure 7 A perspective view of a partial structure of the operating mechanism of an isolating circuit breaker provided in one embodiment of the present utility model. Detailed Implementation

[0024] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0025] It should be understood that the steps described in the method embodiments of this utility model may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of this utility model is not limited in this respect.

[0026] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to". The term "connection" can refer to a direct connection or an indirect connection via intermediate components (elements). The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Definitions of other terms will be given in the following description.

[0027] It should be noted that the concepts of "first" and "second" mentioned in this utility model are only used to distinguish between devices, modules or units, and are not used to limit these devices, modules or units to necessarily be different devices, modules or units, nor are they used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0028] This utility model relates to an isolation operation interlocking structure for installation in the operating mechanism of an isolating circuit breaker. At least a portion of its structure is horizontally positioned in front of the operating contact 210 on the reversing motor 200 within the operating mechanism. This structure can prevent the isolating operating handle from entering the position where it engages with the operating contact 210 when the isolating circuit breaker's intermediate door is open or the opening / closing mechanism is closed, thus obstructing the connection between the isolating operating handle and the operating contact 210 on the reversing motor 200. When the isolating circuit breaker's intermediate door is closed or the opening / closing mechanism is open, the structure allows the isolating operating handle to enter the position where it connects with the operating contact 210. By rotating the operating contact 210 on the motor via the isolating operating handle, the direction of rotation of the reversing motor 200 is changed, causing the three-phase poles of the circuit breaker to operate in the isolation position or the circuit-connected position. Therefore, the isolation operation of the isolating circuit breaker is limited to the middle gate being closed and the opening and closing mechanism being in the open state, avoiding the operation of the isolating switch when the middle gate is open or the opening and closing mechanism is closed, thus improving the safety of the isolation operation and avoiding the risk of electric shock.

[0029] The isolation operation interlocking structure includes a middle door interlocking structure 10 and a circuit breaker interlocking structure 20. The middle door interlocking structure 10 and the circuit breaker interlocking structure 20 are both installed close to the operating contact 210 and are respectively located on opposite sides of the operating contact 210.

[0030] The middle door interlocking structure 10 is used to block the docking channel between the isolation operating handle and the operating contact 210 when the middle door is open, preventing the isolation operating handle from entering the docking channel and docking with the operating contact 210. When the middle door is closed, it can rotate to allow the docking channel between the isolation operating handle and the operating contact 210 to open under the pressure of the isolation operating handle.

[0031] In one embodiment, the middle door interlocking structure 10 includes a first mounting base 13, a limiting fork 11, and a linkage contact rod 12.

[0032] The first mounting base 13 is used to be installed on the frame 400 of the operating mechanism. It includes a first mounting plate 131 arranged horizontally and a first fixing plate 132 bent downward from the first mounting plate 131. The first mounting plate 131 is provided with a first mounting hole 1311 for mounting a rotating shaft connected to the limit fork 11. The first fixing plate 132 is provided with a first fixing hole 1321 for passing screws through and fixing to the frame 400 of the operating mechanism.

[0033] The limiting fork 11 is rotatably mounted on the first mounting plate 131 by means of a pivot inserted into the first mounting hole 1311. It includes a first limiting arm 111, one end of which is horizontally positioned in front of the operating contact 210.

[0034] The linkage rod 12 includes an integrally formed clamping rod 121 and a pressing rod 122. The clamping rod 121 abuts against the side of the first limiting arm 111 facing the operating contact 210 to restrict the rotation of the first limiting arm 111. That is, when the clamping rod 121 abuts against the side wall of the first limiting arm 111, the first limiting arm 111 cannot rotate toward the operating contact 210. Specifically, the first limiting arm 111 cannot rotate clockwise. The pressing rod 122 is used to receive the pressing action from the pusher 300 inside the middle door and rotates vertically to make the clamping rod 121 move away from the rotation range of the first limiting arm 111, so that the first limiting arm 111 can rotate clockwise under the action of external force (such as the pressing action from the isolation operating handle), thereby making room for the docking channel between the isolation operating handle and the operating contact 210.

[0035] Preferably, the middle door interlocking structure 10 further includes a first tension spring 14, and the limiting fork 11 includes a connecting arm 112 that is integrally connected to the first limiting arm 111 and defines an included angle. The first tension spring 14 is disposed within the included angle, and the two ends of the first tension spring 14 are respectively connected to the first mounting base 13 and the connecting arm 112, for resetting the first limiting arm 111 horizontally in front of the operating contact 210 after the force exerted by the isolation operating handle on the first limiting arm 111 is removed.

[0036] The limiting fork 11 also includes a mounting block 113 at the connection point between the first limiting arm 111 and the connecting arm 112. The mounting block has a pivot hole 1131, so that the limiting fork 11 can be rotatably mounted on the first mounting plate 131 by means of a pivot passing through the pivot hole and the first mounting hole 1311.

[0037] Preferably, the side of the first mounting plate 13 away from the first mounting hole 1311 extends in a direction away from the first mounting hole 1311 to form a spring connecting arm, on which a spring connecting hole 1312 is provided, and one end of the first tension spring 14 is hooked onto the spring connecting hole 1312.

[0038] In one embodiment, the connecting arm 112 is provided with a plurality of spring connecting holes 1121 along the length direction. The other end of the first tension spring 14 can be hooked onto one of the spring connecting holes 1121 as needed, so that the elastic force of the first tension spring 14 can be adjusted to ensure that the first limiting arm 111 can be accurately reset.

[0039] Preferably, one end of the clamping rod 121 is connected to the pressing rod 122 and defines an acute angle, and the width of the pressing rod 122 gradually decreases in the direction away from the clamping rod 121; the linkage rod 12 also includes a counterweight head 123, which is connected to the connection part of the clamping rod 121 and the pressing rod 122, and the counterweight head 123 has a pivot hole 1231 for a pivot shaft to pass through so that the linkage rod 12 can rotate around the pivot shaft.

[0040] By setting the width of the contact rod 122 to gradually decrease in the direction away from the clamping rod 121 and connecting it to the counterweight head 123, the center of gravity of the linkage contact rod 12 is lowered. The linkage contact rod 12 can automatically reset under the action of gravity after the clamping action of the middle door is removed, so that the clamping rod 121 clamps against the first limit arm 111.

[0041] The opening and closing interlocking structure 20 is used to link with the opening and closing mechanism in the operating mechanism. When the opening and closing mechanism is in the closed state, it blocks the docking channel between the isolation operating handle and the operating contact 210, preventing the isolation operating handle from entering the docking channel and docking with the operating contact 210. When the opening and closing mechanism is in the open state, it can rotate to open the docking channel between the isolation operating handle and the operating contact 210 under the pressure of the isolation operating handle.

[0042] In one embodiment, the opening and closing interlocking structure 20 includes a second mounting base 23, a limiting crank arm 21, and a linkage block 22.

[0043] The second mounting base 23 is used to fix to the frame 400 of the operating mechanism. It includes a second mounting plate 231 arranged horizontally and a second fixing plate 232 formed by bending one end of the second mounting plate 231 upward. The second mounting plate 231 has a second mounting hole 2311 for passing through a rotating shaft and connecting to the limiting crank arm 21. The second fixing plate 232 has a fixing hole 2321 for passing through a screw and connecting to the frame.

[0044] The limiting arm 21 includes a second limiting arm 211 arranged laterally and a stop arm 212 arranged vertically and connected to one end of the second limiting arm 211. The second limiting arm 211 is rotatably mounted on the second mounting base 23, and its end away from the stop arm 212 is arranged horizontally in front of the operating contact 210. The linkage block 22 is used to link with the opening and closing mechanism, and can rotatably enter the rotation path of the stop arm 212 and restrict the rotation of the limiting stop arm 212.

[0045] In one embodiment, the opening and closing interlocking structure 20 further includes a second tension spring 24, used to reset the second limit arm 211 horizontally in front of the operating contact 210 after the force exerted by the isolation operating handle on the second limit arm 211 is removed. The second tension spring 24 is located on the side of the limit arm 21 facing the forward and reverse motor 200. The second limit arm has a protrusion near the stop arm, and the protrusion has a spring connecting hole 214; the second mounting plate has a spring connecting hole 2312 at one end where the second mounting hole is located, and the two ends of the second tension spring are respectively hooked into the spring connecting hole 214 of the second limit arm and the spring connecting hole 2312 of the second mounting plate.

[0046] In one embodiment, the opening and closing interlocking structure 20 further includes a limiting post 25 for limiting the rotation angle of the second limiting arm 211; the second limiting arm 211 is provided with a shaft hole 213 and a limiting groove 215, the shaft hole 213 is provided at one end of the second limiting arm 211 near the stop arm 212 and is used to pass through a shaft and connect to the second mounting base 23, the limiting groove 215 is provided on the side of the shaft hole 213 near the stop arm 212 and is located on the inner side of the second limiting arm 211 facing the forward and reverse motor 200; the second mounting base 23 is provided with a second mounting hole 2311 and a limiting post mounting hole 2314 corresponding to the shaft hole and the limiting groove 215 respectively; the limiting post 25 is inserted into the limiting post mounting hole 2314 of the second mounting base 23 and abuts against the inner side of the limiting groove 215.

[0047] In addition, it is understood that the second mounting plate 231 is also provided with a clearance notch 2313 that cooperates with the housing of the forward and reverse motor, and the limiting post mounting hole 2314 is set near the clearance notch 2313.

[0048] In one embodiment, the limiting crank arm 21 and the limiting fork 11 are both configured to rotate horizontally, while the linkage block 22 and the linkage contact rod 12 rotate vertically. This cleverly utilizes the movement of two planes to jointly achieve the limiting operation of the isolation handle, thus reducing the size of the interlocking structure. Specifically, the limiting crank arm 21 and the limiting fork 11 move in opposite directions under the force of the isolation handle; one rotates clockwise, and the other rotates counterclockwise.

[0049] Secondly, this utility model also provides an isolating circuit breaker, including three-phase poles, an operating mechanism, and the aforementioned isolating operation interlocking structure. The operating mechanism is used to switch the operating state of the three-phase poles, enabling the isolating circuit breaker to operate in either a circuit breaker or isolator state, and can correspondingly switch the circuit breaker to operate in either an open or closed state, and the isolator to operate in either an isolating or connecting state. The operating mechanism includes a forward and reverse motor 200 with an operating contact 210, and the operating state of the isolator can be switched by rotating the operating contact 210. The opening and closing interlocking structure 20 and the middle door interlocking structure 10 are located on opposite sides of the operating contact 210, and are respectively linked to the opening and closing mechanism and the opening and closing of the middle door. Because the isolating circuit breaker adopts the aforementioned isolating operation interlocking structure, its isolation operation is safer and more reliable than existing isolating circuit breakers, and the overall size of the isolating circuit breaker is also smaller than that of existing isolating circuit breakers.

[0050] The above description is merely a preferred embodiment of this utility model and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of this utility model is not limited to the specific combination of the above-described technical features, but also includes other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features of this utility model that have similar functions.

[0051] Although the subject matter has been described using language specific to structural features and / or methodological logic, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

Claims

1. An isolation operation interlocking structure, for being installed in the operating mechanism of an isolating circuit breaker and located near the operating contacts of the forward and reverse motor of the operating mechanism, characterized in that, This includes the interlocking structure of the middle door and the opening and closing interlocking structure that are set on opposite sides of the operating contact during installation; The middle door interlocking structure is used to block the docking channel between the isolation operating handle and the operating contact when the middle door is open, preventing the isolation operating handle from entering the docking channel and docking with the operating contact. When the middle door is closed, it can rotate to allow the docking channel between the isolation operating handle and the operating contact to open up under the pressure of the isolation operating handle. The opening and closing interlocking structure is used to link with the opening and closing mechanism. When the opening and closing mechanism is in the closed state, it blocks the docking channel between the isolation operating handle and the operating contact to prevent the isolation operating handle from entering the docking channel and docking with the operating contact. When the opening and closing mechanism is in the open state, it can rotate to open the docking channel between the isolation operating handle and the operating contact under the pressure of the isolation operating handle.

2. The isolation operation interlocking structure according to claim 1, characterized in that, The middle door interlocking structure includes a first mounting base, a limit fork, and a linkage contact rod; The first mounting base is used to mount onto the frame of the operating mechanism; The limiting fork is rotatably mounted on the first mounting base, and includes a first limiting arm, one end of which is horizontally positioned in front of the operating contact. The linkage contact rod includes a clamping rod and a pressing rod. The clamping rod abuts against the side of the first limiting arm facing the operating contact. The pressing rod is used to receive the pressing action from the middle door and rotates in the vertical direction to make the clamping rod leave the rotation range of the first limiting arm.

3. The isolation operation interlocking structure according to claim 2, characterized in that, The middle door interlocking structure also includes a first tension spring. The limiting fork includes a connecting arm that is integrally connected to the first limiting arm and defines an included angle. The first tension spring is located within the included angle and its two ends are respectively connected to the first mounting base and the connecting arm. It is used to reset the first limiting arm horizontally in front of the operating contact after the force exerted by the isolation operating handle on the first limiting arm is removed.

4. The isolation operation interlocking structure according to claim 3, characterized in that, The connecting arm is provided with multiple spring connecting holes along its length, and the first tension spring hook is provided on the spring connecting holes.

5. The isolation operation interlocking structure according to claim 2, characterized in that, The clamping rod is connected to one end of the pressing rod and defines an acute angle; the width of the pressing rod gradually decreases in the direction away from the clamping rod. The linkage contact rod also includes a counterweight head, which is connected to the connection between the clamping rod and the pressing rod. The counterweight head has a pivot hole for the linkage contact rod to rotate around the pivot.

6. The isolation operation interlocking structure according to claim 1, characterized in that, The opening and closing interlocking structure includes a second mounting base, a limiting crank arm, and a linkage block. The second mounting base is used to fix it to the frame of the operating mechanism. The limiting crank arm includes a second limiting arm arranged in a horizontal direction and a stop arm arranged in a vertical direction and connected to one end of the second limiting arm. The second limiting arm is rotatably mounted on the second mounting base, and its end away from the stop arm is horizontally positioned in front of the operating contact. The linkage block is used to link with the opening and closing mechanism, rotatably enters the rotation path of the stop arm, and restricts the rotation of the limiting stop arm.

7. The isolation operation interlocking structure according to claim 6, characterized in that, The opening and closing interlocking structure also includes a second tension spring, which is located on the side of the limit arm facing the forward and reverse motor. One end of the spring is hooked on the second mounting base, and the other end is hooked on the end of the second limit arm near the stop arm. It is used to reset the second limit arm horizontally in front of the operating contact after the force of the isolation operating handle on the second limit arm is removed.

8. The isolation operation interlocking structure according to claim 6, characterized in that, The opening and closing interlocking structure also includes a limiting post for limiting the rotation angle of the second limiting arm; The second limiting arm is provided with a rotating shaft hole and a limiting groove. The rotating shaft hole is located at one end of the second limiting arm near the stop arm and is used to pass through the rotating shaft and connect to the second mounting base. The limiting groove is located on the side of the rotating shaft hole near the stop arm and on the side of the second limiting arm facing the forward and reverse motor. The second mounting base is provided with a second mounting hole and a limit post mounting hole respectively corresponding to the shaft hole and the limit groove; The limiting post is inserted into the limiting post mounting hole of the second mounting base and abuts against the inner side of the limiting groove.

9. The isolation operation interlocking structure according to claim 6, characterized in that, The opening and closing interlocking structure is configured such that the limiting crank arm rotates horizontally and the linkage block rotates vertically.

10. An isolating circuit breaker, comprising an operating mechanism, said operating mechanism including a forward and reverse rotating motor having operating contacts, characterized in that, It also includes the isolation operation interlocking structure according to any one of claims 1 to 9, wherein the opening and closing interlocking structure and the middle door interlocking structure are arranged on opposite sides of the operating contact.

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