High-voltage misconnection prevention self-recovery protection device and method for weak current switching circuit

Abstract

The invention relates to the technical field of circuit protection, in particular to a self-recovery protection device and method for preventing high-voltage misconnection of a weak current switching circuit, and the device comprises a circuit protection mechanism which comprises a protection lead, and the two ends of the protection lead are respectively connected with a positive terminal and a ground terminal of a power input end of a mainboard weak current circuit. A self-recovery fuse is arranged on the protection wire in series, and a piezoresistor connected with the self-recovery fuse in parallel is further arranged on the protection wire. The circuit protection mechanism is connected with the weak current part of the control mainboard, when a worker misconnects a high-voltage power supply, the resettable fuse can be instantaneously disconnected, meanwhile, the resistance value of the piezoresistor is suddenly reduced, most of current is shared, the current is led into the ground, and then the safety of the weak current part is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of circuit protection technology, specifically to a self-resetting protection device and method for preventing high-voltage misconnection in low-voltage switch circuits. Background Technology

[0002] In the control system of a heat pump unit, the control motherboard is the most important core component. It integrates a power supply module, a central processing module, a signal processing module, a communication interface module, and various sensor interfaces. The modules work together to achieve precise monitoring and control of the heat pump unit.

[0003] The control board includes both high-voltage and low-voltage sections. The high-voltage section primarily connects to the unit's power supply and powers high-power actuators, while the low-voltage section handles signal processing and data transmission. To ensure stable and accurate signal transmission, the low-voltage section is typically designed as a low-voltage circuit, with a common rated operating voltage of 24V. However, during the actual installation and maintenance of heat pump units, due to varying levels of expertise among maintenance personnel and the complex on-site environment, workers sometimes mistakenly connect 220V AC power to the low-voltage port. Because the components in the low-voltage section are selected for low-voltage specifications, connecting a 220V high-voltage power supply can instantly cause the low-voltage section to burn out due to overvoltage, leading to the entire control board malfunctioning.

[0004] In addition, existing control boards are fixedly installed inside the unit via mounting brackets. During operation, the compressor and fan of the heat pump unit generate vibrations, which are indirectly transmitted to the control board. Prolonged high-frequency vibration significantly affects the stability of component solder joints and damages component pins, thus directly impacting the lifespan of the control board. Therefore, we propose a self-resetting protection device and method for preventing high-voltage misconnection in low-voltage switching circuits to effectively address the aforementioned drawbacks. Summary of the Invention

[0005] The purpose of this invention is to provide a self-resetting protection device and method for preventing high voltage misconnection in low-voltage switching circuits, in order to solve the problems mentioned in the background art.

[0006] This invention is achieved through the following technical solution: a self-resetting protection device for preventing high-voltage misconnection in a low-voltage switch circuit, comprising: The circuit protection mechanism includes a varistor and a resettable fuse. The two ends of the varistor are respectively connected to the positive terminal and the ground terminal of the power input terminal of the control motherboard's low-voltage circuit. The resettable fuse is connected in series with the positive terminal of the power input terminal of the low-voltage circuit. The mounting base has a through-hole on its top wall, and a motherboard mounting part is located on the top wall of the mounting base. The bottom of the motherboard mounting part is provided with a mounting sleeve, which is inserted into the through-hole on the top wall of the mounting base. The mounting base has a retaining ring on the lower surface of its top wall at the cutout. The inner wall of the retaining ring has an annular cavity. The annular cavity contains a connecting sleeve for fixed connection with the mounting sleeve. The connecting sleeve is also provided with a rotating sleeve. The connecting sleeve and the rotating sleeve are connected by an elastic component. The rotating sleeve is also provided with a fixing component, which can be detachably contacted with the connecting sleeve. When the fixing component is not in contact with the connecting sleeve, the connecting sleeve and the rotating sleeve are elastically connected; when the fixing component is in contact with the connecting sleeve, the connecting sleeve and the rotating sleeve are fixedly connected. The circuit protection mechanism is located on the inner side of the motherboard mounting section.

[0007] Optionally, the motherboard mounting portion has an internally hollow structure with several ventilation holes on its top surface. The mounting sleeve has a cylindrical structure and is connected to the interior of the motherboard mounting portion. A cooling fan is installed inside the mounting sleeve. Both the connecting sleeve and the rotating sleeve are annular, and the rotating sleeve rotates in conjunction with the inner wall of the annular cavity. The elastic component is a rubber sleeve, with both ends of the rubber sleeve glued to the connecting sleeve and the rotating sleeve, respectively.

[0008] Optionally, the fixing component includes a sleeve disposed on the inner wall of the rotating sleeve, a positioning post disposed inside the sleeve, and the positioning post and the sleeve being elastically connected by a spring. The inner annular wall of the annular cavity has a drive groove adapted to the positioning post. In its natural state, one end of the positioning post passes through the rotating sleeve and abuts against the inner wall of the drive groove. The drive groove has an A end and a B end. The outer surface of the connecting sleeve has positioning holes distributed and aligned with the positioning post. When the outer end of the positioning post abuts against the A end, the inner end of the positioning post is not inserted into the positioning hole. When the outer end of the positioning post abuts against the B end, the inner end of the positioning post is inserted into the positioning hole.

[0009] Optionally, the number of fixing components is at least four, and the fixing components are evenly spaced along the circumference of the mounting sleeve. The retaining ring and the top wall of the mounting base are rotatably fitted. The top of the retaining ring is provided with a rotating body. The top wall of the mounting base has an arc-shaped opening for the rotating body to pass through. A positioning ring is connected to the outside of the rotating body, and the positioning ring is detachably fixed to the top wall of the mounting base. Spring ball bearings are fixedly embedded in the inner wall of the annular cavity at positions directly opposite the two ends of the drive groove along the vertical direction. Limiting holes are formed in the outer wall of the rotating sleeve at positions opposite the positioning pins along the vertical direction. When the outer ends of the positioning pins abut against ends A and B of the drive groove, the two spring ball bearings are respectively embedded in the limiting holes.

[0010] This invention also proposes a self-resetting protection method for preventing high-voltage misconnection in low-voltage switch circuits, applicable to the aforementioned self-resetting protection device for preventing high-voltage misconnection in low-voltage switch circuits, comprising the following steps: When testing the circuit board, first make the fixing component and the connecting sleeve contact to fix the circuit board relative to the mounting bracket. If 220V AC power is mistakenly connected directly to the power input terminal of a low-voltage circuit when connecting the power supply, the resettable fuse will trip instantly. At the same time, the resistance of the varistor will drop sharply under high voltage to allow the current to be conducted to the ground, preventing overvoltage from burning out the main circuit board. After the test is completed, the fixing components and connecting sleeves are separated so that the circuit board and the mounting base are elastically connected, thereby achieving a buffering and vibration reduction effect.

[0011] Compared with the prior art, the present invention provides a self-resetting protection device and method for preventing high voltage misconnection in low-voltage switching circuits, which has the following beneficial effects: 1. This invention connects the circuit protection mechanism to the low-voltage part of the control board. When the operator accidentally connects to a high-voltage power supply, the self-resetting fuse can break the circuit instantly, and at the same time, the resistance of the varistor drops sharply and the current is introduced to the ground, thereby ensuring the safety of the low-voltage part of the control board. 2. The motherboard mounting part and the mounting base in this invention can be either elastically connected or fixedly connected. Specifically, when the motherboard is in operation, the motherboard mounting part and the mounting base are elastically installed to achieve buffer protection for the motherboard. When the motherboard needs maintenance, it is fixedly installed to facilitate the disassembly and assembly of components on the motherboard. 3. When switching between flexible and fixed installation, this invention only requires holding the motherboard mounting part and rotating the positioning ring, making the operation simple and convenient. Attached Figure Description

[0012] Figure 1 This is a circuit diagram of the circuit protection mechanism of the present invention; Figure 2 This is a schematic diagram of the structure of the present invention; Figure 3 This is a cross-sectional view of the structure of the present invention; Figure 4 This is a schematic diagram of the mounting base structure of the present invention; Figure 5 This is a schematic diagram of the retaining ring structure of the present invention; Figure 6 This is a schematic diagram of the connecting sleeve and rotating sleeve structure of the present invention; Figure 7 This is a cross-sectional view of the ring structure of the present invention; Figure 8 for Figure 3Enlarged view of point A in the middle.

[0013] In the diagram: 100, Circuit protection mechanism; 101, Varistor; 102, Resettable fuse; 200, Mounting base; 201, Mainboard mounting section; 202, Mounting sleeve; 203, Cooling fan; 300, Retaining ring; 301, Drive slot; 302, Rotating body; 303, Positioning ring; 304, Spring ball bearing; 400, Connecting sleeve; 401, Positioning hole; 500, Rotating sleeve; 501, Limiting hole; 600, Elastic component; 700, Fixing component; 701, Tube sleeve; 702, Positioning post. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Example 1: Please refer to Figure 1 - Figure 8 This application proposes a self-resetting protection device for preventing high-voltage misconnection in a low-voltage switch circuit, including a circuit protection mechanism 100 and a mounting base 200. The circuit protection mechanism 100 includes a varistor 101 and a self-resetting fuse 102. The two ends of the varistor 101 are respectively connected to the positive terminal and ground terminal of the power input terminal of the control motherboard low-voltage circuit. The self-resetting fuse 102 is connected in series with the positive terminal of the power input terminal of the low-voltage circuit. Specifically, the operating current of the control motherboard low-voltage circuit is about 0.1A, and the holding current of the self-resetting fuse 102 in this application is slightly higher than 0.1A, for example, 0.15A. When the low-voltage circuit is mistakenly connected to 220V AC power, a high current, such as 10A, will be generated instantaneously in the circuit. This high current is much greater than the operating current of the self-resetting fuse 102, thereby temporarily breaking the circuit and cutting off the subsequent current path.

[0016] Furthermore, the varistor 101 exhibits the characteristic that its resistance decreases as the voltage increases. In this application, the operating voltage of the control motherboard's low-voltage circuit is 24V, while the varistor 101's varistor voltage must be less than 220V. The clamping voltage is lower than the maximum withstand voltage of the low-voltage circuit, ensuring that the varistor 101 can quickly conduct after a 220V power supply is mistakenly connected, diverting the high-voltage energy to ground. Simultaneously, the varistor 101's overvoltage response is on the nanosecond level; its resistance drops sharply the instant a 220V high-voltage connection is made, rapidly discharging the high-voltage current to ground and instantly clamping the low-voltage input voltage. This prevents the high voltage from damaging the motherboard's signal processing chip, communication interface, and other precision low-voltage components within the extremely short time it takes for the fuse to blow, thus solving the defect of a single fuse having a "delay in blowing."

[0017] In this embodiment, the top wall of the mounting base 200 has a through-hole, and a motherboard mounting part 201 is provided above the top wall of the mounting base 200. The motherboard mounting part 201 is used to install the control motherboard, and a mounting sleeve 202 is provided at the bottom of the motherboard mounting part 201. The mounting sleeve 202 is inserted into the through-hole in the top wall of the mounting base 200. Specifically, both the mounting base 200 and the motherboard mounting part 201 are made of hard plastic and have good insulation properties. In addition, the through-hole is circular, and the mounting sleeve 202 is cylindrical.

[0018] As one embodiment and not a limitation, the lower surface of the top wall of the mounting base 200, located at the cutout, is provided with a retaining ring 300. The inner ring wall of the retaining ring 300 has an annular cavity, and a connecting sleeve 400 for fixed connection with the mounting sleeve 202 is provided in the annular cavity. A rotating sleeve 500 is also provided outside the connecting sleeve 400. The connecting sleeve 400 and the rotating sleeve 500 are connected by an elastic component 600. A fixing component 700 is also provided on the rotating sleeve 500. The fixing component 700 can be detachably contacted with the connecting sleeve 400. When the fixing component 700 is not in contact with the connecting sleeve 400, the connecting sleeve 400 and the rotating sleeve 500 are elastically connected. When the fixing component 700 is in contact with the connecting sleeve 400, the connecting sleeve 400 and the rotating sleeve 500 are fixedly connected. Therefore, the connecting sleeve 400 can be fixedly connected to the rotating sleeve 500, or it can be flexibly connected to the rotating sleeve 500. Specifically, when the heat pump unit is in operation, the connecting sleeve 400 can be flexibly installed to provide vibration reduction for the control board. Conversely, when maintaining the control board, the connecting sleeve 400 can be fixedly installed to facilitate the disassembly and assembly of components on the board, thus making maintenance easier.

[0019] It is worth mentioning that the motherboard mounting part 201 has a hollow structure with internal cutouts, and several heat dissipation holes are also provided on the top surface of the motherboard mounting part 201. The circuit protection mechanism 100 is located inside the motherboard mounting part 201. Therefore, when installing the control motherboard, the control motherboard can be fixed to the top surface of the motherboard mounting part 201 first, and then the circuit protection mechanism 100 can be connected to the power input terminal of the low-voltage circuit on the motherboard.

[0020] As one embodiment and not a limitation, the mounting sleeve 202 has a cylindrical structure and is internally connected to the motherboard mounting portion 201. A cooling fan 203 is installed inside the mounting sleeve 202. Therefore, when the cooling fan 203 is turned on, a negative pressure can be generated inside the motherboard mounting portion 201, thereby absorbing the heat generated by the motherboard and preventing it from overheating due to prolonged operation.

[0021] like Figure 8 As shown, both the connecting sleeve 400 and the rotating sleeve 500 are annular, and the rotating sleeve 500 is rotatably fitted to the inner ring wall of the annular cavity. Specifically, a bearing is fixedly embedded in the outer ring wall of the rotating sleeve 500, and the rotating sleeve 500 is rotatably connected to the inner surface of the annular cavity through this bearing. Furthermore, both the connecting sleeve 400 and the rotating sleeve 500 are made of aluminum alloy, which has the advantages of high hardness and light weight. The elastic component 600 uses a rubber sleeve, and both ends of the rubber sleeve are glued and fixed to the connecting sleeve 400 and the rotating sleeve 500 respectively. In this embodiment, the number of rubber sleeves is not less than four, and the rubber sleeves are evenly spaced. The gap width between the connecting sleeve 400 and the rotating sleeve 500 is between 1.5cm and 2.0cm. The connecting sleeve 400 can move in any direction (up, down, left, right) inside the rotating sleeve 500, and is protected by the elastic force of the rubber sleeve.

[0022] As one embodiment and not a limitation, the fixing component 700 includes a sleeve 701 disposed on the inner wall of the rotating sleeve 500. The sleeve 701 is provided with a positioning post 702. The positioning post 702 and the sleeve 701 are elastically connected by a spring. The inner ring wall of the annular cavity has a drive groove 301 adapted to the positioning post 702. In its natural state, one end of the positioning post 702 passes through the rotating sleeve 500 and abuts against the inner wall of the drive groove 301. It should be noted that the positioning post 702 is in the shape of a stepped shaft. The two ends of the spring abut against the step of the positioning post 702 and the inner end of the sleeve 701, respectively. The spring is in a compressed state and applies an outward pushing force to the positioning post 702, so that its outer end always abuts against the inner wall of the drive groove 301. The drive groove 301 has an A end and a B end, as shown in the figure. The drive groove 301 is deep at one end and shallow at the other end, with the deeper end being the A end and the shallower end being the B end. The outer surface of the connecting sleeve 400 has positioning holes 401 that are aligned with the positioning pins 702. When the outer end of the positioning pin 702 abuts against the A end, the inner end of the positioning pin 702 is not inserted into the positioning hole 401. When the outer end of the positioning pin 702 abuts against the B end, the inner end of the positioning pin 702 is inserted into the positioning hole 401.

[0023] like Figure 8 As shown, the number of fixing components 700 is at least four, and the fixing components 700 are evenly spaced along the circumference of the mounting sleeve 202. The diameter of the positioning hole 401 is adapted to the diameter of the positioning post 702. When the positioning post 702 is inserted into the positioning hole 401, the position of the connecting sleeve 400 can be fully fixed, thereby indirectly controlling the fixed installation of the main board. In addition, since the connecting sleeve 400 and the rotating sleeve 500 are only connected by a rubber sleeve, the positioning hole 401 is not completely aligned with the positioning post 702. Therefore, in order to facilitate the smooth entry of the positioning post 702 into the positioning hole 401, the port of the positioning hole 401 can be designed to be flared, or the inner end of the positioning post 702 can be designed to be constricted, so that the positioning post 702 can be more easily inserted into the positioning hole 401.

[0024] As one embodiment and not a limitation, the retaining ring 300 and the top wall of the mounting base 200 are rotatably fitted. The top of the retaining ring 300 has a rotating body 302. The top wall of the mounting base 200 has an arc-shaped opening through which the rotating body 302 passes. The center of this arc-shaped opening coincides with the center of the retaining ring 300, and the inner width of the arc-shaped opening matches the thickness of the rotating body 302. A positioning ring 303 is externally connected to the rotating body 302. The positioning ring 303 is fixedly connected to the rotating body 302 via a connecting rod, and the positioning ring 303 is detachably fixedly connected to the top wall of the mounting base 200. Specifically, the top of the positioning ring 303 has a bolt, and a threaded hole corresponding to the bolt is opened on the upper surface of the mounting base 200, directly below the positioning ring 303. When the bolt is screwed into the corresponding threaded hole, the positions of the positioning ring 303 and the retaining ring 300 are fixed.

[0025] To ensure relative fixation between the rotating sleeve 500 and the retaining ring 300, this embodiment also incorporates the following design: spring ball bearings 304 are fixedly embedded in the inner wall of the annular cavity at positions vertically opposite to both ends of the drive groove 301; a limiting hole 501 is formed on the outer wall of the rotating sleeve 500 at a position vertically opposite to the positioning post 702; when the outer end of the positioning post 702 abuts against end A of the drive groove 301, the ball bearing of one of the spring ball bearings 304 is embedded in the limiting hole 501; when the outer end of the positioning post 702 abuts against end B of the drive groove 301, the ball bearing of the other spring ball bearing 304 is embedded in the limiting hole 501, thereby maintaining the relative fixation between the rotating sleeve 500 and the retaining ring 300.

[0026] In this embodiment, during the initial implementation, the control motherboard is in a flexible installation state, with the outer end of the positioning post 702 abutting against end A of the drive groove 301. To adjust the installation state of the control motherboard, the operator first loosens the bolts on the positioning ring 303, then holds the motherboard mounting part 201 with one hand and rotates the positioning ring 303 with the other until it can no longer be rotated. At this point, the positioning post 702 abuts against end B of the drive groove 301, and a spring ball 304 located at end B is also embedded in the corresponding limiting hole 501. The inner end of the positioning post 702 is inserted into the positioning hole 401, and the connecting sleeve 400 and the rotating sleeve 500 are relatively fixed. The rotating sleeve 500 and the retaining ring 300 are also relatively fixed. Finally, the bolts on the positioning ring 303 are tightened to completely fix the position of the retaining ring 300. Conversely, when it is necessary to switch the control motherboard from a fixed installation to a flexible installation, simply perform the same operation as above and rotate the positioning ring 303 in the opposite direction.

[0027] Example 2: This application proposes a self-resetting protection method for preventing high-voltage misconnection in a low-voltage switch circuit, applicable to the self-resetting protection device for preventing high-voltage misconnection in the low-voltage switch circuit described in Example 1 above, comprising the following steps: When testing the circuit board, first make the fixing component 700 and the connecting sleeve 400 contact each other so that the circuit board is fixedly installed relative to the mounting base 200; that is, rotate the positioning ring 303 so that the positioning pins 702 can be inserted into the corresponding positioning holes 401 to fix the position of the connecting sleeve 400 and ensure that the control board can remain stable during the test.

[0028] When connecting the power supply, if 220V AC power is mistakenly connected directly to the power input terminal of the low-voltage circuit, the resettable fuse 102 will instantly trip, and the resistance of the varistor 101 will drop sharply under the action of high voltage, so that the current can be conducted to the ground to prevent the overvoltage from burning out the control board. This embodiment has a dual protection mechanism of varistor 101 and resettable fuse 102, which can effectively protect the safety of the control board in case of misconnection.

[0029] After testing, the fixing component 700 and the connecting sleeve 400 are separated to allow the circuit board to be elastically connected to the mounting base 200, thereby achieving a buffering and vibration reduction effect. That is, the positioning ring 303 is rotated in the opposite direction to separate the positioning post 702 and the positioning hole 401 again. At this time, the connecting sleeve 400 and the rotating sleeve 500 are connected by a rubber sleeve, thus achieving the elastic installation of the control board.

[0030] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A self-resetting protection device for preventing high-voltage misconnection in a low-voltage switch circuit, characterized in that, include: The circuit protection mechanism includes a varistor and a resettable fuse. The two ends of the varistor are respectively connected to the positive terminal and the ground terminal of the power input terminal of the control motherboard's low-voltage circuit. The resettable fuse is connected in series with the positive terminal of the power input terminal of the low-voltage circuit. The mounting base has a through-hole on its top wall, and a motherboard mounting part is provided above the top wall of the mounting base. The bottom of the motherboard mounting part is provided with a mounting sleeve, which is inserted into the through-hole on the top wall of the mounting base. The mounting base has a retaining ring on the lower surface of its top wall at the cutout. The inner wall of the retaining ring has an annular cavity. A connecting sleeve for fixed connection with the mounting sleeve is provided in the annular cavity. A rotating sleeve is also provided outside the connecting sleeve. The connecting sleeve and the rotating sleeve are connected by an elastic component. A fixing component is also provided on the rotating sleeve. The fixing component can be detachably contacted with the connecting sleeve. When the fixing component is not in contact with the connecting sleeve, the connecting sleeve and the rotating sleeve are elastically connected; when the fixing component is in contact with the connecting sleeve, the connecting sleeve and the rotating sleeve are fixedly connected. The circuit protection mechanism is located on the inner side of the motherboard mounting section.

2. The self-resetting protection device for preventing high-voltage misconnection in a low-voltage switch circuit according to claim 1, characterized in that: The motherboard mounting section has a hollow structure with internal cutouts, and several heat dissipation holes are also provided on the top surface of the motherboard mounting section.

3. The self-resetting protection device for preventing high-voltage misconnection in a low-voltage switch circuit according to claim 1, characterized in that: The mounting sleeve has a cylindrical structure and is connected to the interior of the motherboard mounting section.

4. The self-resetting protection device for preventing high-voltage misconnection in a low-voltage switch circuit according to claim 1, characterized in that: A cooling fan is installed inside the mounting sleeve.

5. The self-resetting protection device for preventing high-voltage misconnection in a low-voltage switch circuit according to claim 1, characterized in that: Both the connecting sleeve and the rotating sleeve are annular, and the rotating sleeve and the inner ring wall of the annular cavity are in rotational fit.

6. The self-resetting protection device for preventing high-voltage misconnection in a low-voltage switch circuit according to claim 5, characterized in that: The elastic component is made of rubber sleeve, and the two ends of the rubber sleeve are glued and fixed to the connecting sleeve and the rotating sleeve, respectively.

7. The self-resetting protection device for preventing high-voltage misconnection in a low-voltage switch circuit according to claim 5, characterized in that: The fixing component includes a tube sleeve disposed on the inner wall of the rotating sleeve, a positioning post disposed inside the tube sleeve, and the positioning post and the tube sleeve are elastically connected by a spring. The inner ring wall of the annular cavity has a drive groove adapted to the positioning post. In the natural state, one end of the positioning post passes through the rotating sleeve and abuts against the inner wall of the drive groove. The drive groove has an A end and a B end. The outer surface of the connecting sleeve has positioning holes that are aligned with the positioning pins. When the outer end of the positioning pin abuts against the A end, the inner end of the positioning pin is not inserted into the positioning hole. When the outer end of the positioning pin abuts against the B end, the inner end of the positioning pin is inserted into the positioning hole.

8. The self-resetting protection device for preventing high-voltage misconnection in a low-voltage switch circuit according to claim 7, characterized in that: The number of fixing components is at least four, and the fixing components are evenly spaced along the circumference of the mounting sleeve.

9. A self-resetting protection device for preventing high-voltage misconnection in a low-voltage switch circuit according to claim 7, characterized in that: The retaining ring and the top wall of the mounting base are rotatably fitted. The top of the retaining ring is provided with a rotating body. The top wall of the mounting base is provided with an arc-shaped opening for the rotating body to pass through. A positioning ring is connected to the outside of the rotating body. The positioning ring is detachably fixed to the top wall of the mounting base. Spring beads are fixedly embedded in the inner wall of the annular cavity at the positions directly opposite the two ends of the drive groove along the vertical direction. Limiting holes are opened on the outer wall of the rotating sleeve at the positions of the positioning pins along the vertical direction. When the outer ends of the positioning pins abut against the A and B ends of the drive groove respectively, the two spring beads are respectively embedded in the limiting holes.

10. A method for self-resetting protection against high-voltage misconnection in a low-voltage switch circuit, applicable to the self-resetting protection device for high-voltage misconnection in a low-voltage switch circuit as described in any one of claims 1-9, characterized in that, Includes the following steps: When testing the circuit board, first make the fixing component and the connecting sleeve contact to fix the circuit board relative to the mounting bracket. If 220V AC power is mistakenly connected directly to the power input terminal of a low-voltage circuit when connecting the power supply, the resettable fuse will trip instantly. At the same time, the resistance of the varistor will drop sharply under high voltage to allow the current to be conducted to the ground, preventing overvoltage from burning out the main circuit board. After the test is completed, the fixing components and connecting sleeves are separated so that the circuit board and the mounting base are elastically connected, thereby achieving a buffering and vibration reduction effect.

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