Alarm for cable theft prevention

Abstract

The utility model belongs to the technical field of cables, particularly relates to an alarm for cable theft prevention, and provides the following scheme aiming at the problems of complex structure, inconvenience in installation, non-ideal alarm effect and the like existing in most of the existing cable theft prevention alarm devices: the alarm comprises a lower half shell and an upper half shell, the lower half shell is positioned below the upper half shell, and the upper half shell is positioned below the lower half shell; the lower half shell and the upper half shell are combined to form a tubular structure for clamping and connecting two sections of cables; the cable anti-theft alarm further comprises a control box and an installation box, the control box is fixedly installed on the top of the upper half shell, the installation box is fixedly installed on the top of the control box, the cable anti-theft alarm is compact in structure and convenient to install, the upper half shell and the lower half shell are combined to clamp a cable, and a control module, an alarm module and a power supply module are integrated on the top of the upper half shell; the state of the cable is monitored in real time through the triggering and communicating assembly, the buzzer can be triggered in time to give an alarm when the cable is cut off illegally, and theft prevention is effectively achieved. The application range is wide, and the practicability is high.

Description

Technical Field

[0001] This utility model relates to the field of cable technology, and in particular to an alarm device for cable theft prevention. Background Technology

[0002] Cables, as a vital medium for power transmission and signal transmission, play a crucial role in various engineering projects and applications. Cable theft can lead to power or signal outages. However, existing cable theft alarm systems still have the following problems in use:

[0003] Most existing cable burglar alarm devices suffer from problems such as complex structure, inconvenient installation, and unsatisfactory alarm effect. Some of these devices require an external power supply, which not only increases the difficulty of installation but also limits their application range. Furthermore, the installation and maintenance costs of these devices are further increased, making them unsuitable for installation and use.

[0004] To address the aforementioned problems, this utility model document proposes an alarm device for cable theft prevention. Utility Model Content

[0005] The purpose of this invention is to address the shortcomings of existing cable anti-theft alarm devices, such as complex structure, inconvenient installation, and unsatisfactory alarm effect, and to propose an alarm device for cable anti-theft.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] Alarms used for cable theft prevention include:

[0008] The lower half shell and the upper half shell are located below the upper half shell. The lower half shell and the upper half shell are combined to form a tubular structure for clamping and connecting two sections of cable.

[0009] It also includes a control box and a mounting box. The control box is fixedly installed on the top of the upper shell, and the mounting box is fixedly installed on the top of the control box. A buzzer is fixedly embedded in the top of the mounting box, and the buzzer is used to emit an audible alarm to the outside world.

[0010] It also includes a battery compartment located at the top, and the battery compartment contains a battery used to power the buzzer.

[0011] It also includes a triggering component, which is used to connect the circuit between the battery and the buzzer;

[0012] It also includes a connecting component, which is used to connect the two cable segments and simultaneously connect the trigger component to the cable current.

[0013] In one possible design, the triggering component includes a fixing block fixedly installed inside the control box. The fixing block has a through hole inside, and the top and bottom inner walls of the through hole are provided with clearance grooves. Movable electrodes are slidably connected inside the two clearance grooves. One of the movable electrodes is electrically connected to a battery, and the other is electrically connected to a buzzer. A third spring is fixedly installed on the side of the two movable electrodes that is far apart from each other. The other end of each of the two third springs is fixedly connected to one inner wall of the clearance groove.

[0014] In one possible design, the triggering assembly further includes a slider slidably mounted inside the control box. A protrusion is fixedly mounted on the side of the slider near the fixed block, and the protrusion mates with a through hole. A connecting electrode is fixedly embedded inside the protrusion, with its two ends penetrating the top and bottom of the protrusion, respectively. The two ends of the connecting electrode mate with two movable electrodes. Two fixed rods are fixedly mounted on one side of the slider, with one end of each fixed rod slidably penetrating the fixed block and one side of the control box. Tension springs are fitted on the outer walls of both fixed rods, with one end of each tension spring fixedly connected to the inner wall of one side of the control box, and the other end of each tension spring fixedly connected to the outer wall of the corresponding fixed rod. The two tension springs are used to pull the slider to move, thereby causing the protrusion to insert into the through hole, thus completing the tight contact between the connecting electrode and the two movable electrodes. An electromagnet is fixedly mounted on the inner wall of the control box away from the tension springs. A sheet metal layer is provided on one side of the slider, and the electromagnet and the slider are magnetically connected through the sheet metal layer to ensure that the connecting electrode and the two movable electrodes are separated when energized.

[0015] In one possible design, the connecting component includes a fixed tube embedded in the inner wall of the top of the upper shell, a movable block slidably connected inside the fixed tube, an electrode plate disposed at the bottom of the movable block, and the electrode plate electrically connected to the electromagnet; a threaded rod is fixedly installed on the inner wall of the bottom of the lower shell, the threaded rod is used to complete the winding connection of two cable segments, the threaded rod is made of conductive material, one end of the threaded rod is slidably engaged with the inner wall of the fixed tube, and the other end of the threaded rod is engaged with the electrode plate at the bottom of the movable block, the threaded rod is used to complete the connection between the electromagnet and the external circuit current; a first spring is disposed inside the fixed tube, one end of the first spring is fixedly connected to the top of the movable block, and the other end of the first spring is fixedly connected to the inner wall of the fixed tube, the first spring is used to ensure that the electrode plate and one end of the threaded rod are tightly fitted.

[0016] In one possible design, a nut is threaded onto the outer wall of the threaded rod, the nut being located below a fixing tube used to press and fix the cable wire wound around the outer wall of the threaded rod.

[0017] In one possible design, a first fixing plate is fixedly installed on both sides of the lower shell, and a second fixing plate is fixedly installed on both sides of the upper shell. Correspondingly, two mounting holes are opened in the first fixing plate and the second fixing plate, and multiple mounting holes are correspondingly connected and bolts are installed through them. The lower shell and the upper shell are locked together by bolts.

[0018] In one possible design, two compression strips are fixedly installed on the inner walls of both the lower and upper shells. Multiple compression strips are located near both ends of the lower and upper shells, and the multiple compression strips are used to ensure that the lower and upper shells have a good clamping and fixing effect on the cable.

[0019] In one possible design, both the lower and upper shells are made of insulating material, an insulating pad is provided at the connection between the threaded rod and the lower shell, and the fixing tube is made of insulating material to prevent the outer shells of the lower and upper shells from becoming electrified.

[0020] In this application, during use, the user needs to connect the device to the corresponding circuit. Specifically, select two cables to be connected in the circuit, place one end of the cable to be connected into the lower half-shell, then wind the cable wires onto the threaded rod, and use a nut to press and fix the wires to ensure a stable connection and also to ensure that the threaded rod can communicate with the circuit. Then, place the upper half-shell on top of the lower half-shell, ensuring that one end of the threaded rod is inserted into the fixing tube. Then, use bolts to lock the lower and upper half-shells together, thus completing the connection of the two cables. When the threaded rod is inserted into the fixing tube, under the action of the first spring, the moving block will cause its bottom electrode plate to remain in close contact with the threaded rod, thereby achieving communication between the electromagnet and the external circuit. After the circuit is powered on, the electromagnet will be simultaneously energized and activated, attracting the slider to remain in close contact with it. The user then needs to ensure the battery compartment is filled with batteries for the device to operate continuously. When the external circuit experiences a power outage due to cable theft or equipment damage, the electromagnet will shut down. The slider, losing its electromagnetic attraction, will be pulled by the tension spring. At this point, a protrusion on one side of the slider will insert into the through-hole, allowing the connecting electrode to contact the two moving electrodes within the fixed block. This close contact between the connecting electrode and the two moving electrodes connects the internal circuitry, powering the buzzer. The buzzer will then emit an audible alarm, alerting nearby personnel to promptly check and repair the device.

[0021] Beneficial effects: In this utility model, the alarm for cable theft prevention can form a tubular structure by combining the lower half shell and the upper half shell to clamp and connect the two sections of cable. At the same time, the control box, mounting box, battery compartment and other components are fixedly installed on the top of the upper half shell, making the whole device compact and easy to install.

[0022] In this invention, the alarm for cable theft prevention achieves real-time monitoring of the cable connection status through the combined use of a triggering component and a connecting component. When the cable is illegally cut or disassembled, the connecting component is disconnected, causing the electromagnet to lose power. The slider moves under the action of the tension spring, making the connecting electrode close to the two moving electrodes, thereby connecting the circuit between the battery and the buzzer. The buzzer then emits an audible alarm, effectively preventing the cable from being stolen.

[0023] In this utility model, the alarm device for cable theft prevention is made of insulating material for both the lower and upper shells, and an insulating pad is provided at the connection between the threaded rod and the lower shell. The fixing tube is also made of insulating material, which effectively avoids the risk of the outer shell being electrified and improves the safety of the device.

[0024] In this utility model, the alarm for cable theft prevention is battery powered, eliminating the need for an external power source. This allows the device to be widely used in various environments without an external power source, while also simplifying maintenance and greatly improving the applicability of the device.

[0025] In this utility model, the alarm for cable theft prevention, with its threaded rod and nut design, not only achieves the winding connection of two cable segments, but also completes the connection between the electromagnet and the external circuit current through the conductivity of the threaded rod. This makes the device not only have the function of theft prevention, but also the function of cable connection, making it more practical.

[0026] This utility model features a compact and easy-to-install cable anti-theft alarm. The cable is held in place by a combination of upper and lower shells, with control, alarm, and power supply modules integrated at the top of the upper shell. It utilizes triggering and connection components to monitor the cable status in real time, triggering a buzzer alarm when the cable is illegally cut, effectively preventing theft. The insulating material and pad design ensure the outer shell remains uncharged, enhancing safety. Battery-powered, it requires no external power source, making it widely applicable in environments without electricity. Maintenance is simple, and it has a wide range of applications and strong practicality. Attached Figure Description

[0027] Figure 1 This is a three-dimensional structural diagram of the alarm device for cable theft prevention proposed in this utility model;

[0028] Figure 2 This is a schematic diagram showing the disassembled structure of the alarm device for cable theft prevention proposed in this utility model;

[0029] Figure 3 This is a cross-sectional structural diagram of the alarm device for cable theft prevention proposed in this utility model;

[0030] Figure 4 This is an enlarged structural diagram of part A of the alarm device for cable theft prevention proposed in this utility model;

[0031] Figure 5 This is a schematic diagram showing the disassembled structure of the control box of the alarm device for cable theft prevention proposed in this utility model;

[0032] Figure 6 This is a schematic diagram of the fixing block structure of the alarm device for cable anti-theft proposed in this utility model.

[0033] In the diagram: 1. Lower shell; 2. Upper shell; 3. Control box; 4. Mounting box; 5. Buzzer; 6. Battery compartment; 7. First fixing plate; 8. Mounting hole; 9. Extrusion strip; 10. Threaded rod; 11. Nut; 12. Second fixing plate; 13. Battery; 14. Electromagnet; 15. Slider; 16. Connecting electrode; 17. Fixing block; 18. Fixing tube; 19. Moving block; 20. First spring; 21. Fixing rod; 22. Tension spring; 23. Through hole; 24. Relief groove; 25. Moving electrode; 26. Third spring. Detailed Implementation

[0034] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0035] Example 1: Refer to Figure 1-6 An alarm device, comprising:

[0036] The lower half-shell 1 and the upper half-shell 2 are located below the upper half-shell 2. Together, they form a tubular structure used to clamp and connect the two cable sections. This design ensures that the cable is securely held inside the alarm, preventing theft or damage.

[0037] The alarm also includes a control box 3 and a mounting box 4. The control box 3 is fixedly installed on the top of the upper shell 2, and the mounting box 4 is fixedly installed on the top of the control box 3. A buzzer 5 is fixedly embedded in the top of the mounting box 4. The buzzer 5 is used to emit an audible alarm to alert the surrounding people when the cable is stolen or when an abnormal situation occurs.

[0038] In addition, the alarm also includes a battery compartment 6, which is located on the top of the mounting box 4. The battery compartment 6 contains a battery 13, which powers the buzzer 5 to ensure the alarm works properly.

[0039] To establish a circuit connection between battery 13 and buzzer 5, the alarm also includes a triggering assembly. The triggering assembly includes a fixing block 17 fixedly installed within the control box 3, with a through hole 23 inside the fixing block 17. Both the top and bottom inner walls of the through hole 23 have recessed grooves 24, and movable electrodes 25 are slidably connected inside each recessed groove 24. One movable electrode 25 is electrically connected to battery 13, and the other movable electrode 25 is electrically connected to buzzer 5. A third spring 26 is fixedly installed on the side of each movable electrode 25 that is furthest from each other, and the other ends of both third springs 26 are fixedly connected to one inner wall of the recessed groove 24. Under normal conditions, the two movable electrodes 25 are kept separate due to the pulling force of the third springs 26, thereby disconnecting the circuit between battery 13 and buzzer 5.

[0040] To connect the two cable segments and simultaneously energize the trigger assembly and the cable, the alarm also includes a connecting component. This connecting component includes a fixed tube 18 embedded in the inner wall of the top of the upper shell 2, with a movable block 19 slidably connected inside the fixed tube 18. An electrode plate is located at the bottom of the movable block 19, electrically connected to the electromagnet 14. A threaded rod 10 is fixedly installed on the inner wall of the bottom of the lower shell 1. The threaded rod 10, made of conductive material, is used to connect the two cable segments by winding them together. One end of the threaded rod 10 slides against the inner wall of the fixed tube 18 and engages with the electrode plate at the bottom of the movable block 19. When the two cable segments are connected through the threaded rod 10, they form a conductive path, energizing the electromagnet 14.

[0041] To ensure that the connecting electrode 16 is separated from the two movable electrodes 25 when energized, the trigger assembly also includes a slider 15 slidably mounted inside the control box 3. A protrusion is fixedly mounted on the side of the slider 15 near the fixing block 17, and the protrusion engages with the through hole 23. The connecting electrode 16 is fixedly embedded inside the protrusion, with both ends of the connecting electrode 16 penetrating the top and bottom of the protrusion respectively, and engaging with the two movable electrodes 25. Two fixing rods 21 are fixedly mounted on one side of the slider 15, with one end of each fixing rod 21 slidably penetrating the fixing block 17 and one side of the control box 3. Tension springs 22 are fitted onto the outer walls of both fixing rods 21, with one end of each tension spring fixedly connected to the inner wall of one side of the control box 3, and the other end fixedly connected to the outer wall of the corresponding fixing rod 21. The two tension springs 22 are used to pull the slider 15 to move, thereby causing the protrusion to insert into the through hole 23, thus ensuring the tight contact between the connecting electrode 16 and the two movable electrodes 25. However, when the electromagnet 14 is energized, it attracts the sheet metal layer on one side of the slider 15, causing the slider 15 to move against the elastic force of the tension spring 22, thereby separating the connecting electrode 16 from the two moving electrodes 25.

[0042] Specifically, an electromagnet 14 is fixedly installed on the inner wall of the control box 3 on the side away from the tension spring 22, and a sheet metal layer is provided on one side of the slider 15. The electromagnet 14 and the slider 15 are magnetically connected through the sheet metal layer. Thus, when the cable is properly connected and energized, the electromagnet 14 will attract the slider 15, causing the connecting electrode 16 to separate from the two moving electrodes 25, thereby disconnecting the circuit between the battery 13 and the buzzer 5. Once the cable is cut or disconnected, the electromagnet 14 will be de-energized, and the slider 15 will move under the action of the tension spring 22, causing the connecting electrode 16 to come into close contact with the two moving electrodes 25, thereby connecting the circuit between the battery 13 and the buzzer 5, causing the buzzer 5 to sound an alarm.

[0043] This application can be used in the field of cable technology, or in other fields applicable to this application.

[0044] Example 2: Reference Figure 1 , 2 An improvement based on Example 1: an alarm for cable theft prevention, which is applied to the field of cable technology;

[0045] To ensure the cable is securely clamped inside the alarm, first fixing plates 7 are fixedly installed on both sides of the lower half-shell 1, and second fixing plates 12 are fixedly installed on both sides of the upper half-shell 2. Each of the corresponding first fixing plates 7 and second fixing plates 12 has two mounting holes 8, and bolts are threaded through these holes. The lower half-shell 1 and upper half-shell 2 are locked together by bolts.

[0046] In addition, two clamping strips 9 are fixedly installed on the inner walls of both the lower half shell 1 and the upper half shell 2. Multiple clamping strips 9 are located near both ends of the lower half shell 1 and the upper half shell 2. These clamping strips 9 are used to increase the clamping force on the cable, ensuring that the cable is securely clamped inside the alarm.

[0047] To press and secure the cable wound around the outer wall of the threaded rod 10, a nut 11 is threaded onto the outer wall of the threaded rod 10, located below the fixing tube 18. After the cable is connected through the threaded rod 10, the nut 11 can be rotated to press it onto the cable, thereby ensuring the stability of the cable connection.

[0048] In addition, both the lower shell 1 and the upper shell 2 are made of insulating material, and an insulating pad is provided at the connection between the threaded rod 10 and the lower shell 1. The fixing tube 18 is also made of insulating material, which can prevent the outer shells of the lower shell 1 and the upper shell 2 from becoming electrified and ensure safety during use.

[0049] However, as is well known to those skilled in the art, the working principles and wiring methods of the buzzer 5 and the electromagnet 14 are commonplace and are all conventional methods or common knowledge. They will not be elaborated here. Those skilled in the art can make any selections according to their needs or convenience.

[0050] The working principle and usage process of this technical solution are as follows: When using the device, the user needs to connect it to the corresponding circuit. Specifically, select two sections of cable to be connected in the circuit, place one end of the cable to be connected into the lower half shell 1, then wrap the wire in the cable around the threaded rod 10, and use the nut 11 to press and fix the wire to ensure a stable connection of the wire, and also to ensure that the threaded rod 10 can be connected to the circuit; then, put the upper half shell 2 on top of the lower half shell 1, and ensure that one end of the threaded rod 10 is inserted into the fixing tube 18 during installation. Then, use bolts to lock the lower half shell 1 and the upper half shell 2, thereby completing the connection of the two sections of cable; when the threaded rod 10 is inserted into the fixing tube 18, under the action of the first spring 20, the moving block 19 will drive the electrode plate at its bottom to continuously stick to the threaded rod 10, thereby realizing the connection between the electromagnet 14 and the external circuit; When the external circuit is powered on, the electromagnet 14 will be simultaneously energized and activated, attracting the slider 15 to remain in close contact with it. The user then needs to ensure that the battery compartment 6 is filled with battery 13 for the device to operate continuously. When the external circuit experiences a power outage due to cable theft or equipment damage, the electromagnet 14 will shut down. Without the attraction of the electromagnet 14, the slider 15 will be pulled by the tension spring 22. At this point, the protrusion on one side of the slider 15 will insert into the through hole 23, allowing the connecting electrode 16 to contact the two movable electrodes 25 within the fixed block 17. The close contact between the connecting electrode 16 and the two movable electrodes 25 will connect the internal circuitry of the device, enabling the battery 13 to power the buzzer 5. The buzzer 5 will then emit an audible alarm, alerting nearby personnel to promptly check and repair the device.

[0051] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. An alarm device for cable theft prevention, characterized in that, include: The lower half shell (1) and the upper half shell (2) are located below the upper half shell (2). The lower half shell (1) and the upper half shell (2) are combined to form a tubular structure for clamping and connecting two sections of cable. It also includes a control box (3) and a mounting box (4). The control box (3) is fixedly installed on the top of the upper shell (2), and the mounting box (4) is fixedly installed on the top of the control box (3). A buzzer (5) is fixedly embedded on the top of the mounting box (4). The buzzer (5) is used to emit a sound alarm to the outside world. It also includes a battery compartment (6), which is located on the top of the mounting box (4). A battery (13) is installed inside the battery compartment (6), and the battery (13) is used to power the buzzer (5). It also includes a triggering component for enabling the connection of the circuit between the battery (13) and the buzzer (5); It also includes a connecting component, which is used to connect the two cable segments and simultaneously connect the trigger component to the cable current.

2. The alarm device for cable theft prevention according to claim 1, characterized in that, The triggering component includes a fixing block (17) fixedly installed in the control box (3). The fixing block (17) has a through hole (23) inside. The top inner wall and bottom inner wall of the through hole (23) are provided with relief grooves (24). The two relief grooves (24) are slidably connected to the interior of each of the two relief grooves (24). One of the relief grooves (25) is electrically connected to the battery (13), and the other relief groove (25) is electrically connected to the buzzer (5). A third spring (26) is fixedly installed on the side of the two relief grooves (25) that are far apart from each other. The other end of the two third springs (26) is fixedly connected to the inner wall of one side of the relief groove (24).

3. The alarm device for cable theft prevention according to claim 2, characterized in that, The triggering assembly also includes a slider (15) slidably mounted inside the control box (3). A protrusion is fixedly mounted on the side of the slider (15) near the fixed block (17). The protrusion cooperates with the through hole (23). A connecting electrode (16) is fixedly embedded inside the protrusion. The two ends of the connecting electrode (16) pass through the top and bottom of the protrusion, respectively. The two ends of the connecting electrode (16) cooperate with two moving electrodes (25), respectively. Two fixing rods (21) are fixedly mounted on one side of the slider (15). One end of each fixing rod (21) slidably passes through the fixed block (17) and one side of the control box (3). A tension spring (22) is sleeved on the outer wall of each fixing rod (21). One end of each tension spring (22) is fixedly connected to the inner wall of one side of the control box (3), and the other end of each tension spring (22) is fixedly connected to the outer wall of the corresponding fixing rod (21). The two tension springs (22) are used to pull the slider (15) to move, thereby inserting the protrusion into the through hole (23) to complete the tight contact between the connecting electrode (16) and the two moving electrodes (25). An electromagnet (14) is fixedly installed on the inner wall of the control box (3) away from the tension spring (22). A sheet metal layer is provided on one side of the slider (15). The electromagnet (14) and the slider (15) are magnetically connected through the sheet metal layer to ensure that the connecting electrode (16) and the two moving electrodes (25) are separated when energized.

4. The alarm device for cable theft prevention according to claim 3, characterized in that, The connecting component includes a fixed tube (18) fixedly embedded in the inner wall of the top of the upper shell (2), a movable block (19) slidably connected inside the fixed tube (18), an electrode plate being provided at the bottom of the movable block (19), and the electrode plate being electrically connected to the electromagnet (14); a threaded rod (10) is fixedly installed on the inner wall of the bottom of the lower shell (1), the threaded rod (10) being used to complete the winding connection of the two cable segments, the threaded rod (10) being made of conductive material, and one end of the threaded rod (10) being connected to the inner wall of the fixed tube (18). The wall sliding fit, one end of the threaded rod (10) is engaged with the electrode plate at the bottom of the moving block (19), the threaded rod (10) is used to complete the connection between the electromagnet (14) and the external circuit current; the fixed tube (18) is provided with a first spring (20), one end of the first spring (20) is fixedly connected to the top of the moving block (19), and the other end of the first spring (20) is fixedly connected to the inner wall of the fixed tube (18), the first spring (20) is used to make the electrode plate and one end of the threaded rod (10) fit tightly together.

5. The alarm device for cable theft prevention according to claim 4, characterized in that, The outer wall of the threaded rod (10) is threaded with a nut (11), which is located below the fixing tube (18). The fixing tube (18) is used to press and fix the cable wire wound on the outer wall of the threaded rod (10).

6. The alarm device for cable theft prevention according to claim 1, characterized in that, The lower shell (1) is fixedly mounted with a first fixing plate (7) on both sides, and the upper shell (2) is fixedly mounted with a second fixing plate (12) on both sides. Correspondingly, the first fixing plate (7) and the second fixing plate (12) each have two mounting holes (8). The multiple mounting holes (8) are corresponding and bolts are installed through them. The lower shell (1) and the upper shell (2) are locked together by bolts.

7. The alarm device for cable theft prevention according to claim 1, characterized in that, The inner walls of the lower shell (1) and the upper shell (2) are each fixedly equipped with two extrusion strips (9). The multiple extrusion strips (9) are located near the two ends of the lower shell (1) and the upper shell (2). The multiple extrusion strips (9) are used to ensure that the lower shell (1) and the upper shell (2) have a good clamping and fixing effect on the cable.

8. The alarm device for cable theft prevention according to claim 4, characterized in that, Both the lower shell (1) and the upper shell (2) are made of insulating material. An insulating pad is provided at the connection between the threaded rod (10) and the lower shell (1). The fixing tube (18) is made of insulating material to prevent the outer shells of the lower shell (1) and the upper shell (2) from becoming electrified.

Images