Low-voltage surge arrester resistant to superhigh current

Abstract

The application relates to the technical field of low-voltage electric appliance protection equipment, in particular to a low-voltage lightning arrester capable of resisting superhigh current, which has the technical scheme that the lightning arrester comprises an annular resistance sheet, arc extinguishing ceramic, an upper copper sheet, a lower copper sheet and a shell; the annular resistance sheet is of an annular hollow structure; the arc extinguishing ceramic is in a cylindrical shape and is coaxially embedded in the hollow inner diameter of the annular resistance sheet; the upper copper sheet and the lower copper sheet are respectively fixed to the upper end face and the lower end face of the arc extinguishing ceramic, and the edges of the upper copper sheet and the lower copper sheet exceed the outer peripheral surface of the arc extinguishing ceramic; the upper copper sheet and the lower copper sheet and the upper and lower end faces of the annular resistance sheet form built-in discharge gaps; and the shell is wrapped outside the annular resistance sheet, and wiring terminals are arranged on the upper and lower ends of the shell. The built-in discharge gaps have fast response speed, can quickly discharge transient superhigh current above 100kA, avoid overloading and burning of the annular resistance sheet, and are suitable for extreme working conditions such as strong lightning strike and strong start-stop of a low-voltage system.

Description

Technical Field

[0001] This invention relates to the field of low-voltage electrical protection equipment technology, specifically to a low-voltage surge arrester that can withstand ultra-high current. Background Technology

[0002] In low-voltage power supply systems, factors such as lightning strikes and frequent start-ups and shutdowns of various high-power electrical equipment can easily trigger high-energy instantaneous overvoltage phenomena. If such sudden overvoltages are not quickly discharged and attenuated through effective protective measures, they will instantly break down the insulation medium of the electrical equipment, leading to a series of serious faults such as the burning of electrical equipment and damage to circuit components, which will have a significant and far-reaching impact on the reliability and stability of the power supply system.

[0003] The existing low-voltage surge arrester has two major structural defects: First, the design of separating the resistor element and the discharge gap results in a delayed response of the discharge gap during overvoltage, which cannot quickly conduct and discharge current, leading to overload and burnout of the resistor element under ultra-high current. Second, the discharge gap is directly exposed to the inside of the resistor element, and the electric arc generated during the discharge process directly contacts the glaze surface of the inner diameter of the resistor element, causing glaze burns and cracks, reducing the insulation performance and service life of the resistor element, and thus affecting the repeated withstand capability of the surge arrester.

[0004] Therefore, there is an urgent need to develop a low-voltage surge arrester with ultra-high current withstand capability that is compact, responds quickly, and can effectively protect the resistor elements from arc damage, in order to make up for the shortcomings of existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a low-voltage surge arrester that can withstand ultra-high current, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a low-voltage surge arrester that can withstand ultra-high current, comprising an annular resistor, an arc-extinguishing ceramic, an upper copper sheet, a lower copper sheet, and a shell, wherein the annular resistor has an annular hollow structure; The arc-quenching ceramic is cylindrical and coaxially embedded in the hollow inner diameter of the annular resistor sheet; The upper copper sheet and the lower copper sheet are respectively fixed to the upper end face and the lower end face of the arc extinguishing ceramic, and the edges of the upper copper sheet and the lower copper sheet extend beyond the outer peripheral surface of the arc extinguishing ceramic. The upper copper sheet and the lower copper sheet form an internal discharge gap with the upper and lower end faces of the annular resistor sheet. The outer shell is wrapped around the outside of the annular resistor sheet, and the upper and lower ends are provided with terminals, which are electrically connected to the upper copper sheet, the lower copper sheet and the annular resistor sheet respectively.

[0007] Preferably, the annular resistor sheet is made of zinc oxide varistor material, with an inner diameter of 20-50 mm, an outer diameter of 40-80 mm, a thickness of 10-20 mm, and a conductive silver layer sprayed on its outer circumference.

[0008] Preferably, the arc-quenching ceramic is made of high alumina ceramic, with a gap between its outer diameter and the inner diameter of the annular resistor sheet ≤ 0.5 mm, and its height is consistent with the thickness of the annular resistor sheet.

[0009] Preferably, the upper and lower end faces of the arc-extinguishing ceramic are provided with annular grooves, and the annular grooves are coated with an insulating elastic coating. The upper copper sheet and the lower copper sheet are fixed in the annular grooves by conductive adhesive.

[0010] Preferably, the upper and lower copper sheets are made of copper with a thickness of 1-3 mm and silver plating. The length of the edges extending beyond the outer periphery of the arc-extinguishing ceramic is 1-3 mm, and the distance of the discharge gap is 0.3-1 mm.

[0011] Preferably, the outer shell is made of epoxy resin insulating material and has a cylindrical structure.

[0012] Preferably, the terminals are made of metal, with the upper terminals electrically connected to the upper copper sheet and the upper end of the annular resistor, and the lower terminals electrically connected to the lower copper sheet and the lower end of the annular resistor.

[0013] Compared with the prior art, the beneficial effects of the present invention are: This invention features a fast response speed due to its built-in discharge gap, which can quickly discharge instantaneous ultra-high currents of over 100kA, preventing the ring resistor from burning out due to overload. It is suitable for extreme operating conditions such as strong lightning strikes and forced start-up and shutdown of equipment in low-voltage systems.

[0014] The arc-extinguishing ceramic in this invention forms an arc isolation area, which effectively prevents the arc from burning the inner diameter glaze of the resistor, extends the service life of the resistor by ≥3 times, and improves the reliability of repeated operation of the surge arrester.

[0015] This invention features a coaxial integrated design of a ring-shaped resistor, arc-extinguishing ceramic, and copper sheet, resulting in a smaller size compared to traditional surge arresters. It also eliminates the need for complex assembly processes, thereby reducing production and installation costs.

[0016] The arc-extinguishing ceramic in this invention has both support and positioning functions as well as arc extinguishing function. The discharge gap spacing is stable over a long period of time and is not affected by environmental vibration or temperature changes, ensuring the long-term reliable operation of the surge arrester. Attached Figure Description

[0017] Figure 1 This is a cross-sectional structural diagram of the present invention.

[0018] In the diagram: 1. Ring-shaped resistor; 2. Arc-extinguishing ceramic; 3. Upper copper sheet; 4. Lower copper sheet; 5. Discharge gap; 6. Housing; 7. Terminal block; 8. Annular groove. Detailed Implementation

[0019] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0020] like Figure 1 As shown, the present invention proposes a low-voltage surge arrester that can withstand ultra-high current, including an annular resistor 1, an arc-extinguishing ceramic 2, an upper copper sheet 3, a lower copper sheet 4, and a shell 6. The annular resistor 1 has an annular hollow structure and is the main conductive component. It is made of zinc oxide varistor material and has a high-resistivity layer sprayed on its outer surface to ensure conductivity and structural strength. The annular hollow structure design enables it to have both current carrying and installation adaptation functions. The outer surface is used to connect to the low-voltage power supply system line and is the main current path during normal operation. The arc-extinguishing ceramic 2 is cylindrical and coaxially embedded in the hollow inner diameter of the annular resistor 1. The arc-extinguishing ceramic 2 is made of high alumina ceramic material, which has the performance of high temperature resistance and rapid arc extinguishing. The gap between its outer diameter and the inner diameter of the annular resistor 1 is controlled within 0.5mm to ensure the compactness of the structure. The upper copper sheet 3 and the lower copper sheet 4 are fixed to the upper and lower end faces of the arc-extinguishing ceramic 2, respectively, and the edges of the upper copper sheet 3 and the lower copper sheet 4 extend beyond the outer circumferential surface of the arc-extinguishing ceramic 2. The upper copper sheet 3 and the lower copper sheet 4 form an internal discharge gap 5 with the upper and lower end faces of the annular resistor 1. The upper copper sheet 3 and the lower copper sheet 4 are circular conductive sheets, fixed to the upper and lower end faces of the arc-extinguishing ceramic 2, respectively, with the edges extending 1 to 3 mm beyond the outer circumferential surface of the arc-extinguishing ceramic 2. They form a stable internal discharge gap 5 with the upper and lower end faces of the annular resistor 1. The gap distance is 0.3 to 1 mm to ensure rapid breakdown and conduction during overvoltage. The outer casing 6 is wrapped around the outer side of the annular resistor 1. Terminals 7 are provided at its upper and lower ends. The terminals 7 are electrically connected to the upper copper sheet 3, the lower copper sheet 4 and the annular resistor 1 respectively. The outer casing 6 is made of epoxy resin insulating material and is wrapped around the outer side of the annular resistor 1 to provide insulation and protection. The metal terminals 7 at the upper and lower ends of the outer casing 6 are used to realize the line connection between the surge arrester and the low-voltage power supply system, and establish a reliable electrical connection with the upper copper sheet 3, the lower copper sheet 4 and the annular resistor 1 respectively.

[0021] Furthermore, the ring-shaped resistor 1 is made of zinc oxide varistor material, with an inner diameter of 30mm, an outer diameter of 60mm, and a thickness of 15mm. The outer circumference is coated with a conductive silver layer to ensure conductivity and structural strength.

[0022] Furthermore, the arc-extinguishing ceramic 2 is made of high alumina ceramic, with a diameter of 30mm and a height of 15mm. The gap between its outer diameter and the inner diameter of the annular resistor 1 is ≤0.5mm, and its height is consistent with the thickness of the annular resistor 1.

[0023] Furthermore, the upper and lower end faces of the arc-extinguishing ceramic 2 are provided with annular grooves 8, and the annular grooves 8 are coated with an insulating elastic coating. The depth of the annular grooves 8 is 1mm. The upper copper sheet 3 and the lower copper sheet 4 are fixed in the annular grooves 8 by conductive adhesive. The annular grooves 8 are used to position the upper copper sheet 3 and the lower copper sheet 4. Fixing them with conductive adhesive can prevent the copper sheets from shifting and ensure the long-term stability of the discharge gap 5.

[0024] Furthermore, the upper copper sheet 3 and the lower copper sheet 4 are made of copper, with a thickness of 2mm and a diameter of 33mm. The surface is silver-plated, and the edge extends 3mm beyond the outer periphery of the arc-extinguishing ceramic 2. They form a discharge gap 5 with a width of 0.5mm with the upper and lower end faces of the annular resistor sheet 1. The upper copper sheet 3 and the lower copper sheet 4 can reduce the contact resistance, improve the conductivity and resistance to arc erosion, and extend the service life of the discharge gap 5.

[0025] Furthermore, the outer casing 6 is made of epoxy resin insulating material, has a cylindrical structure with an outer diameter of 80mm and a height of 30mm, and is wrapped around the outside of the annular resistor 1. Brass terminals 7 are provided at the upper and lower ends. The upper terminal 7 is electrically connected to the upper copper sheet 3 and the upper end of the annular resistor 1, and the lower terminal 7 is electrically connected to the lower copper sheet 4 and the lower end of the annular resistor 1, so as to realize the low-voltage system line access.

[0026] Furthermore, the terminal 7 is made of metal. The upper terminal 7 is electrically connected to the upper copper sheet 3 and the upper end of the annular resistor 1, and the lower terminal 7 is electrically connected to the lower copper sheet 4 and the lower end of the annular resistor 1.

[0027] During assembly, the arc-extinguishing ceramic 2 is first coaxially pressed into the hollow inner diameter of the annular resistor 1, ensuring that the two fit together without looseness and with a gap ≤0.3mm. Conductive silver paste is evenly applied to the inner sides of the upper copper sheet 3 and the lower copper sheet 4, and then embedded into the annular grooves 8 at the upper and lower ends of the arc-extinguishing ceramic 2, respectively. The mixture is left to cure for 24 hours to ensure that the copper sheets are firmly fixed. The assembled annular resistor 1, arc-extinguishing ceramic 2, upper copper sheet 3, and lower copper sheet 4 are then sequentially installed into the outer casing 6. The wiring terminals 7 are fixed with bolts, and the electrical connection reliability is tested. Finally, both ends of the outer casing 6 are sealed to complete the overall assembly.

[0028] Working principle: Under normal working conditions, the working current of the low-voltage power supply system is connected through the outer circumference of the annular resistor 1 and conducts along the body of the annular resistor 1. The discharge gap 5 between the upper copper sheet 3 and the lower copper sheet 4 is in the open state, and the arc-extinguishing ceramic 2 only plays a supporting and positioning role. Under overvoltage conditions, when a transient overvoltage occurs in the system, the discharge gap 5 between the upper copper sheet 3 and the lower copper sheet 4 is instantaneously broken down (breakdown time ≤ 1μs), forming a conductive path. The ultra-high transient current generated by the overvoltage passes through the upper copper sheet 3, the arc-extinguishing ceramic 2, the discharge gap 5, and the lower copper sheet 4 in sequence, and is then quickly released to the ground. Under arc protection conditions, the arc generated during the discharge process is confined between the outer periphery of the arc-extinguishing ceramic 2 and the inner diameter of the annular resistor 1. At this time, the arc-extinguishing ceramic 2 quickly absorbs the arc heat and extinguishes the arc (extinguishing time ≤ 5ms), avoiding direct contact between the arc and the inner diameter glaze of the annular resistor 1, thus achieving glaze protection.

[0029] The above specific embodiments are merely several preferred embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A low-voltage surge arrester capable of withstanding ultra-high current, comprising an annular resistor (1), an arc-extinguishing ceramic (2), an upper copper sheet (3), a lower copper sheet (4), and a casing (6), characterized in that: The annular resistor (1) has an annular hollow structure; The arc-quenching ceramic (2) is cylindrical and coaxially embedded in the hollow inner diameter of the annular resistor (1); The upper copper sheet (3) and the lower copper sheet (4) are respectively fixed to the upper end face and the lower end face of the arc extinguishing ceramic (2), and the edges of the upper copper sheet (3) and the lower copper sheet (4) extend beyond the outer peripheral surface of the arc extinguishing ceramic (2). The upper copper sheet (3) and the lower copper sheet (4) form an internal discharge gap (5) with the upper and lower end faces of the annular resistor (1). The outer shell (6) is wrapped around the outside of the annular resistor (1), and the upper and lower ends are provided with terminals (7). The terminals (7) are electrically connected to the upper copper sheet (3), the lower copper sheet (4) and the annular resistor (1) respectively.

2. A low-voltage surge arrester capable of withstanding ultra-high current according to claim 1, characterized in that: The annular resistor (1) is made of zinc oxide varistor material, with an inner diameter of 20-50 mm, an outer diameter of 40-80 mm, a thickness of 10-20 mm, and a conductive silver layer sprayed on its outer circumference.

3. A low-voltage surge arrester capable of withstanding ultra-high current according to claim 1, characterized in that: The arc-extinguishing ceramic (2) is made of high alumina ceramic, and the gap between its outer diameter and the inner diameter of the annular resistor (1) is ≤0.5mm. Its height is consistent with the thickness of the annular resistor (1).

4. A low-voltage surge arrester capable of withstanding ultra-high current according to claim 1, characterized in that: The upper and lower end faces of the arc-extinguishing ceramic (2) are provided with annular grooves (8), and the annular grooves (8) are coated with an insulating elastic coating. The upper copper sheet (3) and the lower copper sheet (4) are fixed in the annular grooves (8) by conductive adhesive.

5. A low-voltage surge arrester capable of withstanding ultra-high current as described in claim 1 or 4, characterized in that: The upper copper sheet (3) and lower copper sheet (4) are made of copper with a thickness of 1-3 mm and silver plating. The length of the edge extending beyond the outer periphery of the arc-extinguishing ceramic (2) is 1-3 mm. The distance of the discharge gap (5) is 0.3-1 mm.

6. A low-voltage surge arrester capable of withstanding ultra-high current according to claim 1, characterized in that: The outer shell (6) is made of epoxy resin insulating material and has a cylindrical structure.

7. A low-voltage surge arrester capable of withstanding ultra-high current according to claim 1, characterized in that: The terminal (7) is made of metal. The upper terminal (7) is electrically connected to the upper copper sheet (3) and the upper end of the annular resistor (1), and the lower terminal (7) is electrically connected to the lower copper sheet (4) and the lower end of the annular resistor (1).

Images