JPS645415B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a fuse element for a power line fuse that is connected to a power distribution lead-in line and protects the lead-in line from short circuits and overloads. Conventional electric wire fuse elements connect a high temperature fusible material such as silver and a low temperature fusible material such as lead alloy in series, and the high temperature fusible material is blown by an instantaneous large current such as a short circuit current.
Low-temperature fusible materials are required for fuse elements that melt when an overload current exceeding a specified value continues to flow for a specified period of time, and for intermediate parts of high-temperature fusible materials such as silver wire, copper wire, or copper alloy wire. A type of electric wire fuse element is used in which an intermediate terminal having a current capacity and a heat capacity of However, the silver wires used as these high-temperature fusible materials are said to have low electrical resistance and good shearing performance, but are expensive and uneconomical because they are precious metals. Further, copper and copper alloys cannot be said to have sufficient thermal properties. Particularly in the current situation where the price of silver has soared several times over, it has become economically difficult to use silver for the low-voltage wire fuses used in many distribution lines, and it is also problematic from a resource conservation perspective. It's getting better. The present invention solves these economic problems and
What's more, this fuse element has been developed to provide performance comparable to that of silver in terms of shearing properties. As shown in FIG. 1, in a fuse element in which a high-temperature fusible material 1 and a low-temperature fusible material 2 are connected in series to an element terminal 6 via an intermediate terminal 3, a second
As shown in the figure, silver 11 is clad on the surface of the copper wire 12 of the high-temperature fusible body 1 in a structure that lengthens the fusing time during the shearing time and minimizes the arcing time that occurs following the fusing. The thickness of the silver 11 may be approximately 1% of the wire diameter of the copper wire 12, for example. Note that this wall thickness can be made thinner to some extent within the range of predetermined shear characteristics and in consideration of economic aspects. In the drawing, 4 is an explosion-proof insulated tube, 5 is a lead terminal, and 6 is
1 is an element terminal, 7 is a stopper, 8 is a glass tube, 9 is a cap, and 10 is a terminal cover. Next, regarding the characteristics of the fuse element of the present invention, in terms of fusing characteristics for overload protection, the specific resistance of silver is 1.62 μΩcm, and the specific resistance of copper is 1.69 μΩcm.
Ωcm (20°C), the difference between the two is small, and the difference in fusing time for a given current is not much different from that of silver alone, and it is possible to provide the desired fusing characteristics without any particular adjustment. In addition, in terms of curing properties, the melting point of copper is 1083 times higher than when conventional silver is used alone.
℃, which is higher than silver's 960.5℃, as shown in Figure 3, the experimental results revealed that the melting time during the cooling time is longer and the arc time is shorter, and if only silver is used instead. The explosion power at the time of the fuse rupture is also lower than that of the silver, and therefore the burden of the explosion power on the fuse case is also reduced.Furthermore, the amount of evaporated gas is small, and the insulation resistance value between the terminals after the fuse is ruptured is also lower than that of silver. Better test results were obtained than in the case of . Next, I will show you the test results. The shear breakage test was conducted under the test conditions of voltage 220V, standard current 3200A, and shear breakage rate 0.14 (JIS: 0.4 or less). The test sample was high temperature soluble material 1 of the present invention.
In addition to the one using a silver-clad copper wire of a prescribed configuration, four types of wire fuses were used, each using silver, copper, and brass, all of which were wire fuses for 2.6φ wires, and five wire fuses each were tested for comparison. Four types of fuse elements were used for the high-temperature fusible element 1, and the other low-temperature fusible elements 2 were all made of the same material.

[Table] As shown in the table above and Figure 3, the test results show that the silver-clad copper wire with the specified configuration had the shortest shearing time, 9ms (Figure 3a), followed by copper and brass, which had a shearing time of 10ms (Figure 3a). Figure 3b), silver is 14ms (Figure 3c)
This was the longest result. In particular, the arc time, which has the greatest effect on shearing, is the shortest in the case of silver-clad copper wire, which is 5 ms shorter than in the case of silver only.Therefore, the explosive power at the time of shearing is low, and there is no burden on the case. There are also few. In addition, the megger value between both terminals after the shingle break is also the power factor.
Although tested at a power factor as low as 0.14, the fuse element using the silver-clad copper wire of the predetermined configuration of the present invention exhibited a power factor greater than an integer. On the other hand, in the case of fuse elements made of silver, copper, brass, etc., the resistance may be less than JIS 0.2 mΩ, and the fuse element of the present invention achieved significantly better results. This means that the melting point of the high-temperature fusible material 1 made of the silver-clad copper wire of the predetermined configuration of the present invention is higher than that of silver alone, and that the passing current at the time of shearing is between 3300 A for silver and 3800 A for copper/brass. The melting time at 3600A and curing time is not much different from that of silver, copper, and brass, but the arc time was the shortest, and it worked effectively for curing. In the case of copper or brass, the passing current at the time of shear failure is as high as 3800A, as shown in the table, and it melts and evaporates all at once, resulting in a large explosion power and a large amount of evaporation gas. has a low megger value. In addition, silver has a low melting point, so the passing current
Since it is melted and turned into ion gas at 3300A, the arc time is longer, so there is more evaporated gas, and the power at that time is also higher, and there is also more metal gas deposited on the case, which worsens the megger value. In addition, when a fuse element made of a silver-clad copper wire with a specific configuration is shrunk, the arc time is shortest because when the surface silver melts due to the shear breakage current, the surface of the copper in the core melts. The silver causes a wetting phenomenon, and the copper melts all at once, leading to fusing.
This shortens the arc time. Furthermore, since the arc time is short, there is less evaporation gas and less vapor deposition inside the case. Therefore, the megger value after shearing is set to a high value. In addition to the silver-clad copper wire with a predetermined configuration, a silver-clad copper plate with a predetermined configuration can also be used to achieve effects similar to those of the silver-clad copper wire. As described above, the present invention clads the outer periphery of the copper wire with silver in such a manner that the shearing time is increased and the arcing time is minimized. In other words, by cladding the copper wire with approximately 1% of the wire diameter,
It provides a shearing performance that exceeds that of both copper and silver, and it is extremely economical because the amount of silver used can be greatly reduced, and the price of silver wire of the same wire diameter is currently lower. It is a fuse element that is desirable from a resource-saving perspective because it is low-priced, less than 1/10 of that of silver, and, as mentioned above, has better fringing performance than silver.

[Brief explanation of drawings]

FIG. 1 is an explanatory sectional view of the present invention, FIG. 2 is an explanatory sectional view of the high-temperature fusible body of the present invention, and FIG. 3 is a cross-section diagram. 1 is a high temperature fusible material, 2 is a low temperature fusible material, 3 is a middle terminal, 4 is an explosion-proof insulated tube, 5 is a lead terminal, 6 is an element terminal, 7 is a stopper, 8 is a glass tube, 9 is a cap, 10 is a terminal Cover, 11 is silver, 12 is copper wire,
13 is ceramic paper.

Claims (1)

[Claims] 1. In a fuse element in which a high-temperature fusible material and a low-temperature fusible material are connected in series, the fusing time is increased during the shearing time on the surface of the copper wire of the high-temperature fusible material.
In order to minimize the arc time that occurs following fusing, silver is clad with a thickness of approximately 1% of the copper wire diameter, greatly improving the shearing performance. fuse element.