JPS6041411B2 - current limiting fuse - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a current-limiting fuse, and in particular, the present invention relates to a current-limiting fuse. This invention relates to a slit-type current-limiting fuse that exhibits high current-limiting performance by suppressing the expansion of the arc cross-sectional area by confining the arc.

As shown in Figures 1 and 2, conventional current-limiting fuses are
Notch l that melts when overcurrent or short circuit current flows
A fusible body 1 having a diameter a is sandwiched between two insulating plates 2, 2, and the fusible body is held by tightening the insulating plates 2, 2 with screws 3. The insulating plate sandwiching the fusible body 1 in this way is placed in an electrically insulating outer cylinder 4, both ends of the outer cylinder are closed with conductive caps 5, and electrically connected to the fusible body 1, and the outer cylinder 4 and the cap are closed. 5 and the outer cylinder 4 and the cap 5 are bonded with adhesive.
The space formed by these is filled with cinnabar sand 6 in order to suppress the increase in pressure inside the cylinder after the fusible body 1 is fused. The conventional current limiting fuse configured as described above operates as follows.

That is, when a short circuit current flows through the fusible body 1, the fusible body 1 is heated by Joule heat, melts, and vaporizes, and an arc is generated between the two insulating plates 2, 2.

This arc is suppressed from increasing its cross-sectional area by the two insulating plates 2, 2, and is also cooled by the insulating plates 2, 2, so it has a high resistance and the short circuit current is limited and then cut off. Ru. However, when conventional current-limiting fuses attempt to break a high-voltage circuit, a large amount of arced gas is generated, and a large amount of arced gas is emitted from between the two insulating plates 2, 2 as shown by the arrow in Figure 1. Since it blows out to the outside of the insulator, an internal circuit occurs on the side surfaces of the insulating plates 2, 2, resulting in a decrease in arc resistance and a deterioration in current limiting and breaking performance.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and its purpose is to provide a current-limiting fuse that does not reduce its breaking ability even in high-voltage circuits.
The present invention provides a current limiting fuse in which an insulating plate is divided, an arced gas discharge port is provided, and the gas discharge port is provided in a portion of the fusible body that is not a cut portion.

The present invention will be specifically described below with reference to an illustrated embodiment.

As shown in FIGS. 3 and 4, in this invention, one of the two insulating plates 2 is divided into three small insulating plates 2a, 2b, 2c, and the insulating plates 2a, 2b, 2c are divided into three small insulating plates 2a, 2b, 2c. 2 is tightened with a screw 3, a gas discharge port 7 is formed between the insulating plates 2a, 2b, and 2c.

The insulating plates hold the fusible body 1 between them at the notches la so that the gas discharge ports 7 are located in the part of the fusible body where the notches la are not present. The mounting of the fusible body sandwiched between insulating plates in the outer cylinder is the same as in the case of FIGS. 1 and 2, so the same parts are indicated by the same numerals and the explanation will be omitted. Due to the above-described structure of the current-limiting fuse of the present invention, when a short circuit current flows through it, the fusible body 1 generates joules. It is the same as the conventional current-limiting fuse shown in FIG. 1 in that it is heated and fused by heat, and the short-circuit current is limited or cut off.

However, since the gas discharge port 7 is provided between the divided arc extinguishing plates 2a, 2b, and 2c, the arced gas flows out in the direction of the gas discharge port 7, as shown by the arrows in FIGS. 3 and 4. Therefore, compared to those shown in FIGS. 1 and 2, the amount of gas released to the side surface of the insulating plate 2 is significantly reduced. Therefore, the first
This prevents an internal arc from occurring on the side surface of the insulating plate 2, which occurs in the diagram. Therefore, excellent current limiting and disconnection can be obtained even in high voltage circuits. In addition, in this invention, the cut portion la of the fusible body 1 is formed on the insulating plates 2, 2a.
Since the insulating plates 2, 2a, 2b, 2 have a much better thermal conductivity than the cinnabar sand 6, the notches la of the fusible material, where the temperature rise is the largest when an overcurrent is applied, are sandwiched in contact with the insulating plates 2, 2a, 2b, 2.
It is cooled by c. As a result, the temperature rise in the cut portion la of the fusible body 1 can be suppressed, so that thermal deterioration of this portion can be prevented. In the above embodiment, one side of the insulating plate 2 is divided and the gas discharge port 7 is provided between the divided insulating plates 2a, 2b, and 2c, but the other insulating plate 2 may also be divided and a gas discharge port provided therebetween. This makes it possible to reduce the flow rate of the arced gas in the side direction of the insulating plate 2, making it possible to further prevent internal circuits from occurring.

Further, in the illustrated example, one insulating plate is divided into three parts and two gas discharge ports are provided, but it will be easily understood that the number of divisions is not limited to three parts. As described above, according to the present invention, an insulating plate is divided and a gas release port is provided between the insulating plates, and this gas release port is provided in a part of the fusible material that does not have a notch, so that internal circuits can be prevented even in high voltage circuits. This has the effect of not only achieving simulated current limiting and breaking performance but also suppressing the temperature rise at the cut portion of the fusible material and preventing thermal deterioration of this portion.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the inside of a conventional current-limiting fuse with the outer cylinder and cap cut away, FIG. 2 is a side view of the one shown in FIG. 1, and FIG. 3 is an implementation of the current-limiting fuse of the present invention. FIG. 4 is a plan view similar to FIG. 1 showing an example, and FIG. 4 is a side view similar to FIG. 2 of FIG. 3. 1... Fusible body, la... Notch, 2, 2a
, 2b, 2c... Insulating plate, 3... Screw, 4... Outer cylinder, 5... Cap, 6...
...Cinnamon sand, 7...Gas release port. Figure 4 Figure l Figure 2 Figure 3

Claims (1)

[Claims] 1. In a current limiting fuse comprising a fusible body having a notch that fuses when a short circuit current is applied, an insulating plate that sandwiches the fusible body, and an arced gas discharge port provided on the insulating plate, the arced gas discharge port is connected to the A current-limiting fuse characterized by being provided in a part of the fusible body that is not a notch.