Melt of fuse
By designing a new melt structure in the fuse, and combining variable cross-section and narrowing surface, the problem of relatively weak protection of existing fuses during low overload and short circuit protection is solved, and the effect of effectively protecting electrical circuits and electrical equipment in both cases is achieved.
Patent Information
- Application Number
- CN202420671060.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-03
- Publication Date
- 2025-04-18
- Estimated Expiration
- 2034-04-03
AI Technical Summary
When existing fuses face low overload and short circuit protection, the protection effect is relatively weak, making it difficult to effectively protect electrical circuits and electrical equipment in both cases.
A new type of melt structure is designed, with a variable cross-section composed of several holes along the length direction, and a narrowing surface equal to the variable cross-section is set in the intermediate position to ensure that it can be effectively fused under low overload and short circuit conditions.
In the case of low overload, the temperature rises slowly due to the concentration of heating points, and the temperature rises slowly, and the blowing temperature first reaches the blowing temperature; in the case of short circuit or extreme overload, the temperature rises rapidly, and the variable cross-section and narrowing surface are fuse almost at the same time, quickly cutting off the circuit power supply.
Smart Images
Figure CN222775267U_ABST
Abstract
Description
Technical field:
[0001] The utility model relates to a safety protection device for an electrical circuit and electrical equipment, in particular to a fuse structure of a core component of a fuse for providing safety protection for a nuclear power plant protection system. Background technology:
[0002] The fuse is based on the physical variable characteristics of converting electrical energy into heat energy to achieve the protection purpose of long-term operation under normal current and melting and clearing fault current. When the current exceeds the specified value, the heat generated by itself will cause the fuse to melt and disconnect the circuit. When in use, the fuse is connected in series to the protected circuit. When an overload or short-circuit current passes through the fuse, the fuse itself will heat up and melt, thereby playing a certain protective role for the power system, various electrical equipment and household appliances. It is widely used in ships, nuclear power, aviation, rail transportation and other fields.
[0003] The working status of the fuse can be divided into normal working status, low fault protection status and short circuit protection status:
[0004] 1) When the current flowing through the fuse is less than or equal to the rated current of the fuse, the temperature of the fuse gradually rises to a stable state, at which time the fuse can work normally for a long time.
[0005] 2) When the circuit generates a fault current greater than the rated current of the fuse, the fuse can dissipate the energy of the rated current. The excess energy accumulates at the heat source of the fuse and gradually increases to the melting temperature. The fuse will inevitably operate, the fuse will melt, disconnect the line power, and stop the line / system from powering on.
[0006] 3) When the short-circuit current generated by the circuit flows through the fuse, the temperature of the fuse element rises sharply, and the fuse element cannot conduct energy in a very short time, which can be regarded as an adiabatic state. At this time, the fuse element will act quickly, the fuse element will melt, and the line power will be disconnected, causing the line / system to stop supplying power.
[0007] Therefore, when using fuses, the lines or protected electrical facilities usually face the above 2) "low overload state" and 3) "short circuit state" protection conditions.
[0008] In response to the above two protection requirements, the current relevant international and national standards, as well as the industry's general practice, are to design and manufacture fuses suitable for different protection categories based on different protection categories. The fuse materials, fuse structures, and fuse data used are also different. For example, fuses suitable for short-circuit protection are generally called "fast fuses". As the name suggests, when a short circuit or overload occurs, the fuse needs to blow quickly to cut off the circuit and protect the lines or electrical facilities from damage.
[0009] However, in actual use and operation, power lines are subject to the possibility of low overload and short circuit. If the fuse installed in series in the line loop is designed according to the protection category after the overload phenomenon occurs, then its effect on short-circuit protection will be relatively weak and it may not be able to play a role in short-circuit protection; vice versa.
[0010] Therefore, the industry needs fuses that have significant protection in both situations. In particular, in terms of the safety protection of the passive electrical system of nuclear power plants, it is necessary to meet the normal load of the system and ensure that when the system has a low fault current and the system issues an early warning signal, it can give maintenance personnel a certain amount of time to check and troubleshoot the fault; but when the system has a high overload (or "extreme overload") or short-circuit current, it can be quickly disconnected to effectively protect the safety of the system lines and equipment. Summary of the invention:
[0011] In order to solve the above shortcomings, the purpose of the utility model is to provide a fuse with a new structure for use in a fuse. The fuse described in the utility model can be installed for overload protection and short-circuit protection without changing or affecting the original electrical properties of the fuse, and has a simple structure and is easy to arrange and manufacture.
[0012] In order to achieve the above purpose, the utility model provides the following technical solutions:
[0013] 1. A fuse element, characterized in that: the fuse element is provided with variable cross-sections consisting of a plurality of holes arranged side by side at intervals along the length direction, and a narrow path for current to pass is provided between the holes, and there is a place where the width of the fuse element is narrowed between two adjacent variable cross-sections near the middle position of the fuse element, and the cross-sectional area of the narrowed place is equal to the total area of the narrow paths between the holes at the variable cross-section position, so that the current flowing through this place has the same current channel as that at the variable cross-section narrow path, but because the heat dissipation surface is concentrated and narrowed, the melt temperature is higher than that at other narrow paths, and when low overload fusing occurs, the melting temperature is reached first here and the melting is fusing.
[0014] 2. There are folding positions on both sides of the fuse that are connected to the fuse contacts. There are three folding methods according to the position and shape of the contact to be welded. One is to fold 90° directly; one is to fold 90° first, and then fold 90° along the length direction; and the other is to fold 90° first, and then fold a U-shaped bend close to the folding position.
[0015] 3. The shapes of the holes that make up the variable cross-section include circular, diamond-shaped, polygonal, etc.
[0016] Since the utility model provides a fuse structure, the fuse is not only provided with a variable cross section composed of a plurality of holes along the length direction, but also provided with a narrowing surface with the same area as the variable cross section between two adjacent variable cross sections in the middle (center) position. According to the principle that the protection function of the fuse is to rely on the heating and melting of the fuse, compared with the narrowing surface with the same area as the variable cross section position and the variable cross section composed of holes, because the heating position is concentrated here, whether the fuse is in normal working state or in low overload state, the heat dissipation speed will be slower than that of the variable cross section due to the concentrated heating position, so that the temperature of this position is higher than that of other positions. When the line has a low overload phenomenon, the temperature of the entire melt rises slowly and continuously (generally calculated in minutes or seconds), but because the temperature of the cross section at this position is higher than that of the variable cross section at other positions under normal working conditions, the cross section at this position will first reach the melting (melting) temperature, so that this position is melted, and the entire line or power supply facility stops supplying power.
[0017] When a short circuit or extreme overload occurs in the line, the temperature of the melt will rise rapidly. The time difference between the variable cross-section and the narrowed surface on the melt to reach the melting (melting) temperature is very short (generally calculated in milliseconds), which is almost negligible. They basically melt at the same time, thereby quickly cutting off the power supply of the line.
[0018] Therefore, the fuse of this structure makes the current flowing through the narrowed surface become crowded because of the narrowed cross-section, and the heat points are concentrated, and the heat dissipation effect is worse than that of the variable cross-section position. The melt temperature here is higher than that of other positions. When melting, the melting temperature is reached here first; therefore, this structure and the process of making this fuse can be applied to both overload protection and short-circuit protection, and the structure is simple and the layout is convenient to make. It is particularly suitable for the protection of power storage systems of equipment such as energy storage, ships, and aircraft, as well as the safety protection of passive electrical systems in nuclear power plants. It is necessary to meet the normal load of the system to ensure that when a low fault current occurs and the system sends an early warning signal, the maintenance personnel can be given a certain amount of time to check and eliminate the fault; and when the system has a high overload (or "extreme overload") or a short-circuit current, it can be quickly disconnected to effectively protect the safety of the system lines and equipment. Description of the drawings:
[0019] Figure 1 It is a schematic diagram of the melt shape structure of an embodiment of the utility model.
[0020] Figure 2 It is a partial enlarged schematic diagram of the melt cross-section variation in an embodiment of the utility model.
[0021] Explanation of the accompanying reference numerals: A, variable cross-section; B, narrowing surface; 1, variable cross-section hole; 2, narrow diameter. Specific implementation method:
[0022] The utility model is further described below in conjunction with the accompanying drawings.
[0023] Embodiment, a fuse structure of a fuse, as shown in the attached Figure 1 , 2 As shown, the melt is provided with variable cross-sections at intervals along the length direction. The variable cross-section is provided in the width direction of the melt, as shown in the attached figure, and is composed of holes 1 set up side by side, and a narrow path 2 between the holes 1. The current flowing through here passes through the narrow path 2. Compared with other positions, the cross-section here is narrowed, and a narrowing surface is provided between the two variable cross-sections near the middle position. The cross-sectional area at the narrowing surface B is equal to the cross-sectional area at the variable cross-section A. In this way, when a fault current flows through, the temperature of these two places rises first and reaches the melting temperature within a certain time. Compared with the two places, if the current flowing through the line belongs to a low overload current, the narrowing surface B is relative to the variable cross-section A, because the heat points are concentrated and the heat dissipation is more difficult than that at A. Therefore, the temperature at B is higher than that at A. In this way, in terms of melting time, the tolerable melting time here is shorter than the melting time at the variable cross-section A. Therefore, B melts first.
[0024] When a short circuit occurs in the line, the electrical facilities do not bear any load, or bear almost no load. The load is borne entirely or almost entirely by the wires and the fuses connected in series on the line. In a short period of time, the variable cross-section and narrowing surface of the fuse installed in the fuse will generate very large Joule-Lenz heat because of the narrowest cross-section. The temperature of the variable cross-section and narrowing surface of the fuse reaches the melting temperature almost instantly. At this time, the temperature difference between the variable cross-section and narrowing surface can be ignored, and they will melt almost at the same time, cutting off the power supply to the circuit.
[0025] In summary, the fuse of a new structure provided by the design scheme of the utility model has variable cross-sections arranged at intervals along the length direction of the fuse, and a narrowing surface is arranged between the two variable cross-sections near the middle position, the cross-sectional area of the narrowing surface is equal to the cross-sectional area at the variable cross-section, the current channel at the variable cross-section and the narrowing surface is narrower than that at other positions, the temperature in the working state or the fault state is higher than that at other positions, and when the fuse blows, it will first blow from these two positions; and relative to the variable cross-section, although the cross-sectional area at the narrowing surface position is equal to that at the variable cross-section, because the heat points are concentrated here, the heat dissipation speed is more difficult than that at the variable cross-section position, so the temperature here is higher than that at the variable cross-section, so the melting temperature will be reached here first and the fuse will be melted, so no matter it is in the normal working state or in the fault state, the temperature is higher than the temperature at the variable cross-section, so the melt inside the fuse forms a stepped temperature, the temperature at the narrowing surface position is the highest, the temperature at the variable cross-section is the second, and the temperature at other positions on the fuse is the lowest. When an overload occurs, the variable cross-section at the narrowing surface will melt first because the temperature continues to rise slowly.
Claims
1. A fuse element, characterized in that: The melt is provided with variable cross-sections composed of a number of holes arranged side by side at intervals along the length direction, and narrow paths for current to pass are arranged between the holes. There is a place where the melt width is narrowed between two adjacent variable cross-sections near the middle position of the melt, and the cross-sectional area at the narrowing point is equal to the total area of the narrow paths between the holes at the variable cross-section position. In this way, the current flowing through this place has the same current channel as that at the variable cross-section narrow path, but because the heat dissipation surface is concentrated and narrowed, the melt temperature is higher than that at other narrow paths. When low overload melting occurs, the melting temperature is reached here first and it is melted.
2. The fuse element of a fuse according to claim 1, characterized in that: There are folding positions on both sides of the fuse that are connected to the fuse contacts. There are three folding methods according to the position and shape of the weld on the contact. One is to directly fold 90°; one is to fold 90° first, and then fold 90° along the length direction; and the other is to fold 90° first, and then fold a U-shaped bend close to the folding position.
3. The fuse element of a fuse according to claim 1, characterized in that: The shapes of the holes that make up the variable cross-section include circle, diamond, polygon, etc.