JPS6141737A - Cu alloy for electric fuse - Google Patents

Abstract

PURPOSE:To obtain a fuse which fuses in a nearly fixed time when over-current flows by incorporating a specified amount of Sn to a conventional Cu-Zn alloy for a fuse. CONSTITUTION:The electric fuse is made of an alloy having a composition consisting of 37-43% Zn, 0.1-1% Sn and the balance Cu. When over-current flow, the fuse responds at once and fuses in a nearly fixed time. Thus, the fuse has superior reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a Cu alloy that exhibits excellent performance when used as an electrical fuse.

[Conventional technology]

Conventionally, typical Cu alloys for electric fuses include:
A 57% Cu-43% Zn alloy is known, and this Cu
Alloys are mainly used for low voltage and high current applications, and for high voltage applications. However, when the above-mentioned conventional Cu-Zn alloys are used in practical use as electric fuses, there are variations in the fusing time. If there is, the fuse may blow out even if there is no overcurrent (the essential condition for an electric fuse is to blow it within a certain amount of time at an overcurrent of twice the rated current), or vice versa. They are relatively unreliable because they do not melt even when an overcurrent flows, causing problems such as damage to equipment.

[Means for solving problems]

Therefore, the inventors of the present invention, from the above-mentioned viewpoint.

The above conventional Cu alloy for electric fuses, i.e. 57% C
Focusing on the u-43% Zn alloy, we conducted research to reduce the variation in the fusing time as an electric fuse function, and as a result, the results were as follows: Zn: 37 to 43% by weight .

8n: 0.1-1%.

Cu and unavoidable impurities: Remaining.

It was discovered that when a Cu alloy having a composition of

This invention was made based on the above knowledge, and the reason why the component composition was limited as described above will be explained below.

(at Zn The Zn component improves fusing reactivity against overcurrent,
This has the effect of causing melt cutting in a short time, but if the content is less than 37%, the desired effect cannot be obtained, while if the content exceeds 43%, it will cause plate-like, linear, etc. Since it becomes extremely difficult to process into a shaped fuse, the content was set at 37 to 43%.

(b) The 5n Sn component has the property of causing the fuse to blow out immediately in response to an overcurrent, that is, it has the effect of reducing the variation in the blowing time, but if its content is less than 0.1%, the desired effect may not be achieved. The content was determined to be 0.1 to 1% because no effect could be obtained, and even if the content exceeded 1%, no further improving effect would appear due to the above-mentioned action.

In addition, in the Cu alloy of this invention, B, Mg, AJ, Co, Ni, Ag,
Pb.

Even if it contains one or more of Fe, P, etc., if the content is less than 0.1%,
It does not have any adverse effect on the fuse characteristics.

〔Example〕

Next, the Cu alloy of the present invention will be specifically explained using examples.

Using a low-frequency groove-type melting furnace, Cu alloys 1 to 9 of the present invention and conventional Cu alloys having the compositions shown in Table 81 were prepared, and a thickness of 150 m was cast by semi-continuous casting. It was cast into a cake with dimensions of IX width: 40011X length: 1500111, and then hot-rolled into a hot-rolled plate with a thickness of 11m, and then face milled by 0.5 to remove surface scale.
Then, cold rolling, annealing, and pickling were repeated under normal conditions, and finally a cold-rolled plate having a thickness of 0.2 m was final rolled.

Then, five fuses each having a rated current of IOA and 30 A were manufactured from the resulting cold-rolled sheets of the Cu alloys 1 to 9 of the present invention and the conventional Cu alloy.

Note that the rated current varies depending on the composition and cross-sectional area of the fuse, so the rated current of the fuse is 1OA and 3OA.
The width of each fuse was adjusted to the dimensions shown in Table 1 (in this case, the thickness of the fuse was 0.2 m, and the length was 55 mm) so that the current was 0 A.

Subsequently, these fuses were tested using the fusing test apparatus shown schematically in Figure 81 in accordance with Section 5.6 Fusing Test of JISC8352r General Rules for Arranging Fuses and Holders.

In the fusing test device shown in Fig. 1, 1 is a rectangular switch;
is a slider, 3 is a resistor, 4 is a rectifier, 5 is an ammeter, and 6 is a built-in fuse, and by operating the slider 2, the current flowing through the ammeter 5 becomes twice the rated current of the fuse.
In other words, for a fuse with a rated current of 1OA, it is 20A.
After adjusting the 30A fuse to 60A, the fuse was set to fuse setting 6, square switch 1 was turned on, and the time until the fuse blown was measured. This test was conducted for each of five fuses, the longest blowing time and the shortest blowing time were checked, and the variation in blowing time was evaluated based on the difference between the two. These results are also shown in Table 1.

〔Effect of the invention〕

As shown in Table 1, it is clear that all of the fuses manufactured with 5K Cu alloys 1 to 9 of the present invention have extremely small variations in blowing time compared to fuses made of conventional Cu alloys.

As mentioned above, the Cu alloy of the present invention has excellent fusing reactivity and fast response to overcurrent, so when it is used as an electric fuse, the variation in blowing time is extremely small, and it has excellent fuse performance. It exhibits extremely high reliability.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a fusing test device. In the drawings: 1. Rectangular switch, 2. Slider,
3... Resistor, 4... Rectifier, 5... Ammeter, 6... Built-in fuse.

Claims (1)

[Scope of Claims] A Cu alloy for an electric fuse, characterized in that it has a composition (the above weight %) consisting of: Zn: 37 to 43%, Sn: 0.1 to 1%, and the remainder Cu and unavoidable impurities.