A fast current limiting fuse

Abstract

This invention discloses a fast current-limiting fuse, relating to the field of fuse technology. The fuse includes a fuse tube, a contact head, and a contact seat. One end of the fuse tube is connected to the contact head, and the other end is connected to the contact seat. The fuse tube includes a housing and a main fuse wire, insulating particles, a support mechanism, and an impactor disposed within the housing. End caps are connected to both ends of the housing, and the impactor is adjacent to the contact seat. The support mechanism includes several insulating rods and several insulating plates, with each insulating plate connected by a specific insulating rod. The main fuse wire is spirally wound around the support mechanism and connected to the end caps. The support mechanism is hollow, and the insulating particles are located on the inner and outer sides of the support mechanism. In this invention, the support mechanism has a hollow structure, and there are gaps between adjacent insulating plates, which effectively increases the saturation of the quartz sand filling inside the fuse tube, improving the absorption rate of arc energy and arc-extinguishing performance.

Description

Technical Field

[0001] This invention relates to the field of fuse technology, and more particularly to a fast current-limiting fuse. Background Technology

[0002] High-voltage fuses were among the earliest devices used for fault protection in power systems. Connected in series in the circuit, when the current in the protected circuit exceeds a specified value and a certain period of time has elapsed, the heat generated by the fuse itself melts the fusible element, cutting off the faulty circuit and protecting downstream electrical equipment. Currently, high-voltage fuses used in 10kV distribution network lines are divided into ejector-type fuses and current-limiting fuses. However, both ejector-type and current-limiting fuses have several problems in practical use: Ejection-type fuses work by melting a molten element to form an electric arc. The arc's combustion causes a large amount of gas to be released from the insulating tube, resulting in a surge in pressure. This gas is then ejected downwards along the pipe, eventually extinguishing the arc at zero crossing. Although ejection-type fuses have a simple structure, they produce sparks during the ejection process, and the high-temperature residue ejected can easily ignite flammable materials below, posing a significant safety hazard.

[0003] Most current-limiting fuses are currently integrated with load switches to form a unified protection device. Their main principle is that the fusible element is embedded in quartz sand. When a short-circuit current flows, many weak points on the fusible element melt sequentially, dividing the arc into multiple smaller arcs. These arcs burn within the quartz sand, which forms a high-resistivity lava channel, thus reducing the fault circuit current until it is insufficient to sustain the arc, forcing the current to zero. While current-limiting fuses have strong arc-extinguishing capabilities and quickly and safely interrupt faults, their relatively long fusible element and high resistance lead to significant temperature rise at rated current, potentially causing fuse bursting. Furthermore, because most current-limiting fuses use a seven-core ceramic support, the quartz sand does not completely encapsulate the fusible element, resulting in less quartz sand melting during arc combustion and unstable arc-extinguishing time. Summary of the Invention

[0004] In view of the problems of existing current-limiting fuses, such as long fuse length, high resistance, risk of tube bursting, and insufficient insulation particles to fully encapsulate the fuse, this invention provides a fast current-limiting fuse.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A fast-current-limiting fuse includes a fuse tube, a contact head, and a contact base. One end of the fuse tube is connected to the contact head, and the other end is connected to the contact base. The fuse tube includes a shell, a main fuse wire, insulating particles, a support mechanism, and an impactor. End caps are connected to both ends of the shell, forming cavities. The main fuse wire, insulating particles, support mechanism, and impactor are all disposed within the cavities, with the impactor adjacent to the contact base. The support mechanism includes several insulating rods and several insulating plates, with the insulating plates connected to each other via the insulating rods. The main fuse wire is spirally wound around the support mechanism and connected to the end caps. The support mechanism is hollow internally, with the insulating particles located on the inner and outer sides of the support mechanism.

[0006] Furthermore, a sealant is provided between the end cap and the outer shell, the end cap located at one end of the outer shell is connected to the contact head, and the end cap located at the other end of the outer shell is connected to the contact seat.

[0007] Furthermore, the insulating rods and insulating particles are both made of silicon dioxide, and the insulating plates and outer shells are both made of epoxy resin. Each insulating plate has mounting holes, and each insulating rod is disposed within one of the mounting holes.

[0008] Furthermore, each of the insulating plates is annular, and there is a gap between adjacent insulating plates, the gap being filled with insulating particles. There is a space between the support mechanism and the outer shell, the space being filled with insulating particles.

[0009] Furthermore, the impactor includes a tubular guide, a conductive wire, a spring, and an impact pin. The impact pin is disposed within the tubular guide, and a through hole adapted to the impact pin is provided on one side of the tubular guide. The spring is disposed between the tubular guide and the impact pin. The conductive wire is located within the support mechanism, with one end connected to the end cap located at one end of the housing and the other end connected to the impact pin.

[0010] Furthermore, the conductive wire is connected in parallel with the main fuse, and the resistance of the conductive wire is greater than the resistance of the main fuse.

[0011] Furthermore, the contact head includes a connecting ring and a sleeve, the connecting ring being connected to the sleeve, and the sleeve being fitted onto the end cap located at one end of the outer casing.

[0012] Furthermore, the contact seat includes a pipe clamp, a pressure plate, and a bracket, with the pipe clamp disposed on the end cap located at the other end of the housing. One end of the bracket is rotatably connected to one side of the pipe clamp, and the middle portion of the pressure plate is rotatably connected to the other side of the pipe clamp. One end of the pressure plate is adjacent to the impactor, and the other end is detachably connected to the other end of the bracket.

[0013] Furthermore, a pair of connecting plates are provided at the other end of the bracket, and a connecting rod is provided between the two connecting plates.

[0014] Furthermore, the other end of the pressure plate is provided with a hook-shaped connecting part, which is adapted to the connecting rod.

[0015] The beneficial effects of this invention are as follows: 1. The support mechanism in this invention is a hollow structure with gaps between adjacent insulating plates, effectively increasing the saturation of the quartz sand filling inside the fuse tube. This improves the temperature rise performance of the fuse tube under small fault current conditions and increases the absorption rate of arc energy under large fault current conditions, resulting in stronger arc extinguishing performance. Furthermore, it significantly shortens the breaking time under the same fault current, enhancing protection performance. 2. This invention uses a current-limiting fuse tube, preventing explosive ejection during short-circuit fault operation. The internal use of quartz sand for arc extinguishing ensures the entire breaking process is free of explosive noise, pollutant generation, and falling flammable materials. This not only achieves safe and reliable breaking and dropping action but also avoids impacting surrounding equipment and the environment. 3. In this invention, the striking pin and pressure plate work together to drive the connecting part to separate from the connecting rod through rotation. This allows the fuse tube to break and drop under gravity, completing the entire process automatically and rapidly, effectively improving safety. Attached Figure Description

[0016] Figure 1 The diagram shown is a schematic representation of the structural principle of one embodiment of the present invention.

[0017] Figure 2 The figure shown is a cross-sectional view of the present invention.

[0018] Figure 3 for Figure 1 The partial structural diagram shows the structure of the support mechanism.

[0019] Figure 4 The diagram shown is a schematic diagram of the trigger action of the present invention.

[0020] Explanation of reference numerals in the attached drawings: 1. Outer shell; 2. Insulating particles; 3. Support mechanism; 301. Insulating rod; 302. Insulating plate; 4. Main fuse; 5. Conductive wire; 6. Sleeve; 7. Connecting ring; 8. Tubular guide; 9. Strike pin; 10. Spring; 11. Pipe clamp; 12. Bracket; 13. Pressure plate; 14. Connecting rod; 15. Connecting part. Detailed Implementation

[0021] This invention discloses a fast current-limiting fuse. The following describes one aspect of the invention in detail with reference to the accompanying drawings.

[0022] Combination Figure 1 and Figure 2 As shown, a fast current-limiting fuse includes a fuse tube, a contact head, and a contact seat. The fuse tube includes a housing 1, a main fuse 4, insulating particles 2, a support mechanism 3, and an impactor. The housing 1 is made of epoxy resin material and is narrowed at both ends. The upper end is connected to a first end cap by sealant, and the lower end of the housing 1 is connected to a second end cap by sealant. The first end cap, the second end cap, and the housing 1 cooperate to form a cavity. The main fuse 4, the insulating particles 2, the support mechanism 3, and the impactor are all disposed in the cavity.

[0023] like Figure 3 As shown, the support mechanism 3 includes eight insulating rods 301 and at least five insulating plates 302. The insulating rods 301 are glass rods, and the insulating plates 302 are epoxy resin plates. Each insulating plate 302 is annular and has several mounting holes. Each insulating rod 301 is disposed in the mounting holes to connect the insulating plates 302. There are gaps between the insulating plates 302 that can accommodate insulating particles 2. The main fuse 4 is spirally and uniformly wound on the outer surface of the support mechanism 3. The upper end of the main fuse 4 is welded to the inner wall of the first end cap, and the lower end is welded to the inner wall of the second end cap. There is a gap between the support mechanism 3 and the cavity. The insulating particles 2 fill the inner space of the support mechanism 3, the gaps between the insulating plates 302, and the space between the support mechanism 3 and the cavity to fully surround the main fuse 4. The insulating particles 2 are quartz sand.

[0024] The impactor is located at the lower end of the cavity and includes a tubular guide 8, a conductive wire 5, a spring 10, and a striking pin 9. The striking pin 9 is disposed inside the tubular guide 8, and a through hole adapted to the striking pin 9 is provided on one side of the tubular guide 8. The spring 10 is compressed and disposed between the tubular guide 8 and the striking pin 9. The conductive wire 5 is located inside the support mechanism 3, and one end of the conductive wire 5 is connected to the first end cap, while the other end passes through the tubular guide 8 and is connected to the striking pin 9. The conductive wire 5 is connected in parallel with the main fuse 4, and the resistance of the conductive wire 5 is greater than the resistance of the main fuse 4, so that the current mainly flows through the main fuse 4.

[0025] The contact head includes a connecting ring 7 and a sleeve 6, with the connecting ring 7 connected to the sleeve 6, and the sleeve 6 fitted onto the first end cap. The contact seat includes a pipe clamp 11, a pressure plate 13, and a bracket 12, with the pipe clamp 11 fitted onto the second end cap. The upper end of the bracket 12 is rotatably connected to the upper side of the pipe clamp 11, and the lower end is provided with a pair of connecting plates, with a connecting rod 14 between the two connecting plates. The pressure plate 13 is Z-shaped, with its middle part rotatably connected to the lower side of the pipe clamp 11. One end of the pressure plate 13 is adjacent to the through hole of the impactor, and the other end has a hook-shaped connecting part 15, which is adapted to and detachably connected to the connecting rod 14.

[0026] like Figure 4As shown, during use, when the fast-current limiting fuse is installed on the fuse base via bracket 12, the contact head is connected to the power grid input terminal of the distribution network line. Current flows through the contact head, the first end cap, the main fuse 4, the second end cap, the contact seat, and then into the fuse base, thus forming a current path. The first end cap and the second end cap are both sealed to the outer casing 1 with sealant to ensure the integrity of the quartz sand and the main fuse 4, avoid environmental interference, and meet the requirements of outdoor operating environments. When a short-circuit fault occurs in the distribution network line, several weak points on the main fuse 4 will melt sequentially, dividing the arc into multiple small arcs. Since the main fuse 4 is surrounded by quartz sand as insulating particles 2, the arc will burn in the quartz sand, causing the quartz sand to melt due to heat, thereby forming a high-resistance lava channel, which rapidly increases the arc resistance, causing the current in the fault circuit to drop until it is insufficient to maintain the arc and the current is forced to zero. At this time, the short-circuit current will pass through the conductive wire 5. Due to the high resistance of the conductive wire 5, the short-circuit current will instantly generate a large amount of heat energy on the conductive wire 5, melting the conductive wire 5. This will cause the compressed spring 10 to release. The spring 10 will convert its elastic potential energy into elastic force, thereby pushing the striker 9 to move outward along the tubular guide 8 and extend outward through the through hole. After the striker 9 extends out of the tubular guide 8, it will push the pressure plate 13 in the contact seat, causing the pressure plate 13 to rotate relative to the tube clamp 11. This will cause the connecting part 15 to disengage from the connecting rod 14. Under the action of gravity, the fused tube will rotate downward relative to the bracket 12, thereby breaking the current path.

[0027] In practical applications, for existing 10kV distribution transformers, there are already standardized drop-out fuses between the high-voltage line and the transformer. Users can use an insulating rod to remove the fuse carrier and check whether the size of the fuse carrier meets the standard requirements (375mm±1.15mm). If the requirements are met, a fast current-limiting fuse with the same rated current can be directly used for replacement and installation. The operation is simple and convenient.

[0028] For newly built distribution network lines, especially for transformers located close to substation outlets, short-circuit faults can generate extremely large short-circuit currents, potentially affecting the normal operation of the entire substation. Therefore, it is necessary to install fast-acting current-limiting fuses at the high-voltage input of the transformer. In the event of a short-circuit fault, these fuses can disconnect the circuit in an extremely short time (<50ms) and limit the peak fault current, significantly reducing the damage caused by short-circuit faults.

[0029] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A fast current-limiting fuse, characterized in that: The device includes a fusible tube, a contact head, and a contact seat. One end of the fusible tube is connected to the contact head, and the other end is connected to the contact seat. The fusible tube includes a shell (1), a main fuse (4), insulating particles (2), a support mechanism (3), and an impactor. Both ends of the shell (1) are connected to end caps and form cavities. The main fuse (4), insulating particles (2), support mechanism (3), and impactor are all disposed in the cavities. The impactor is adjacent to the contact seat. The support mechanism (3) includes several insulating rods (301) and several insulating plates (302). The insulating plates (302) are connected to each other through the insulating rods (301). The main fuse (4) is spirally wound on the support mechanism (3) and connected to the end caps. The support mechanism (3) is hollow inside, and the insulating particles (2) are located on the inner and outer sides of the support mechanism (3).

2. The fast current-limiting fuse according to claim 1, characterized in that: A sealant is provided between the end cap and the outer shell (1). The end cap located at one end of the outer shell (1) is connected to the contact head, and the end cap located at the other end of the outer shell (1) is connected to the contact seat.

3. A fast current-limiting fuse according to claim 1, characterized in that: The insulating rod (301) and insulating particles (2) are both made of silicon dioxide, and the insulating plate (302) and outer shell (1) are both made of epoxy resin. Each of the insulating plates (302) is provided with a mounting hole, and each of the insulating rods (301) is disposed in the mounting hole.

4. A fast current-limiting fuse according to claim 1, characterized in that: Each of the insulating plates (302) is annular, and there is a gap between adjacent insulating plates (302), the gap being filled with insulating particles (2). There is a space between the support mechanism (3) and the outer shell (1), and the space is filled with insulating particles (2).

5. A fast current-limiting fuse according to claim 1, characterized in that: The impactor includes a tubular guide (8), a conductive wire (5), a spring (10), and a striking pin (9). The striking pin (9) is disposed inside the tubular guide (8). A through hole adapted to the striking pin (9) is provided on one side of the tubular guide (8). The spring (10) is disposed between the tubular guide (8) and the striking pin (9). The conductive wire (5) is located inside the support mechanism (3), with one end connected to the end cap located at one end of the outer shell (1) and the other end connected to the striking pin (9).

6. A fast current-limiting fuse according to claim 5, characterized in that: The conductive wire (5) is connected in parallel with the main fuse (4), and the resistance of the conductive wire (5) is greater than the resistance of the main fuse (4).

7. A fast current-limiting fuse according to claim 1, characterized in that: The contact head includes a connecting ring (7) and a sleeve (6), the connecting ring (7) is connected to the sleeve (6), and the sleeve (6) is sleeved on the end cap located at one end of the outer shell (1).

8. A fast current-limiting fuse according to claim 1, characterized in that: The contact seat includes a pipe clamp (11), a pressure plate (13), and a bracket (12). The pipe clamp (11) is disposed on the end cap located at the other end of the housing (1). One end of the bracket (12) is rotatably connected to one side of the pipe clamp (11), and the middle part of the pressure plate (13) is rotatably connected to the other side of the pipe clamp (11). One end of the pressure plate (13) is adjacent to the impactor, and the other end is detachably connected to the other end of the bracket (12).

9. A fast current-limiting fuse according to claim 8, characterized in that: A pair of connecting plates are provided at the other end of the bracket (12), and a connecting rod (14) is provided between the two connecting plates.

10. A fast current-limiting fuse according to claim 9, characterized in that: The other end of the pressure plate (13) is provided with a hook-shaped connecting part (15), which is adapted to the connecting rod (14).

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