JPH02236929A - Melting display for fuse - Google Patents

Abstract

PURPOSE:To eliminate the applying of the mechanical load to a pilot wire and reduce the minimum operating voltage by forming a melting part in a part of a melting display meltable wire, and detecting the arc light of the melting part at the time of melting, and converting it to electric signal. CONSTITUTION:When the accident current is flowed to a fuse under the feeding, a meltable material 3 and a pilot wire 23 are melted. At this stage, the pilot wire 23 is always melted at a melting part 23a having the narrow sectional area, and the arc light is emitted at this part. This arc light is transmitted from a light receiving end 25a to a sensor through an optical fiber 25 and converted to the electric signal. With the structure, since a mechanical operating part is eliminated, keeping an operating spring under compression condition with the pilot wire is eliminated to reduce the wire diameter of the pilot wire 23. As a result, the wire diameter of the pilot wire 23 can be reduced.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a fuse blowing display device that outputs the blowing operation of a fuse to the outside as an electrical signal.

[Conventional technology]

Fuse blowout display devices have been known that transmit the operation as an electrical signal to a control panel, etc. located far from the fuse installation location, when a current-carrying fuse is cut off due to abnormal current flow such as a fault current. . This blown display device is effective in determining whether a fuse is operating from a distance when many fuses are used in the same location, and the electrical signal is also used to interlock higher-level protection devices such as circuit breakers. used. Conventional fuse blowout indicating devices hold an operating spring in a compressed state with a fusible wire (hereinafter referred to as the indicator wire) for indicating a blowout stretched inside an insulator tube in parallel with a fusible material, and this operation occurs when the indicating wire blows. The structure is such that when the spring is released, the return force operates the mechanical contacts. Fig. 4 is a longitudinal cross-sectional view of a fuse equipped with such a conventional device, and Fig. 5 is an enlarged view of part A; in Fig. 1, 1 and 2 are terminals, and 3 is a connection between terminals The fusible body 3 is made of one or several stretched fusible bodies, and both ends of the fusible body 3 are electrically connected to terminals 1 and 2 by spot welding. This fusible body 3 is housed inside a rectangular cylindrical insulator tube 4, and the circumference thereof is filled with arc-extinguishing sand 5. The terminal 1 is fastened to the insulator tube 4 with a screw 9 through a packing 6, and the terminal 2 is fastened with a screw 9 through a packing 7 and a cover 8.
It is tightened to the insulator tube 4 by. There is a display line 10 between the terminals 1 and 2 along the inner wall surface of the insulator tube 4.
is electrically stretched in parallel with the fusible body 3. On the other hand, the fifth
As shown in detail in the figure, the side wall of the insulator tube 4 has stepped holes 4a.
A packing 11, an operating spring 12, and a display plate 13 are stacked and inserted in this hole 4a in this order. The center portion of the display line 10 is wrapped around the display plate 13, and the operating spring 12 is held in a compressed state by the tension of the display line 10. i1 on the display board 13
4 is installed. Furthermore, in FIG. 1, on the outside of the insulator tube 4, there is a support 16 that is fastened to the insulator tube 4 together with the terminals 1 and 2 with screws 9.
An insulating adapter 15 is attached using screws 19. A contact unit 20 having mechanical display contacts is fixed to the adapter 15.
A display rod 17 is slidably mounted between and M14. Note that the display rod 17 is urged toward the display temporary 13 by a return spring 18 as shown in the figure. In such a configuration, when the fusible body 3 and the indicator line 10 are fused due to an accidental current, the operating spring 12, which is no longer held by the indicator line 10, causes the indicator plate 13 to protrude from the insulator tube 4 by its restoring force. As a result, display bar 1
7 is pushed upward in the figure while compressing the return spring 18 to operate the contact unit 20.

[Problem to be solved by the invention]

As described above, the conventional fusing display device has a structure in which the operating spring is always kept in a compressed state by the display line in order to obtain the operating force that brings the contacts into mechanical contact. Therefore, it is necessary to increase the tensile strength of the display line to a certain value or more, and as a result, there is a problem in that the minimum operating voltage is restricted to a certain value or more. In addition, there was a risk of the display line being cut due to vibration or impact, and there was a problem in terms of vibration resistance. SUMMARY OF THE INVENTION An object of the present invention is to provide a fuse blowout display device that eliminates the above-mentioned drawbacks by not applying mechanical load to the display line.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a fuse in which a fusible body and a fusible wire for blowout indication are stretched inside an insulator tube, in which a part of the fusible wire for blowout indication is fused before other parts. In addition to forming a fusing part, a means for detecting light emission when the fusing part is blown is provided near the fusing part.

[Function 1] In this invention, the arc light accompanying the melting of the display line is detected and converted into an electrical signal. At this time, in order to ensure that the light emission is detected, a fusing part is formed in a part of the display line to be fused before the other part, and a detection means is provided near this fusing part. The above-mentioned fusing part that is cut by fusing before other parts can be formed by cutting. In addition, as a means of detecting arc light, in addition to a structure in which a sensor such as a photocell or photodiode is built into the fuse, a structure in which the sensor is placed externally and the arc light from the fused part is guided to this sensor via an optical fiber is adopted. be able to. Embodiments Hereinafter, embodiments of the present invention will be described based on FIGS. 1 to 3. Here, the first port is a vertical sectional view of a fuse equipped with the device of the present invention, FIG. 2 is an enlarged view of part B thereof, and FIG. 3 is an enlarged view of the main part of the display line in FIG. 2. Incidentally, the same parts as in the conventional example are given the same reference numerals, and the description thereof will be omitted. First, in FIG. 2, the side wall of the insulator tube 4 has stepped holes 21.
is opened, the body of the packing 12 with a barrel is pushed into the small diameter part, and a cylindrical support 22 is inserted into the large diameter part so as to overlap with the packing 12. support 22
There are two small holes 22. in the bottom plate. a is opened and packing 1
The central part of the display line 23 led out through the small hole 22
It is wrapped around the support 22 through a. The part of the display line 23 exposed outside the support 22 is a fusing part 23a.
As shown in FIG. 3, this fusing portion 23a
3 is formed as a constricted portion with a partially narrowed cross-sectional area. On the other hand, in FIG. 1, the light-receiving end 25 of the optical fiber 25 is attached to the support 24 attached to the support 16 with screws 19 at a position where the arc light from the fusing part 23a can be captured.
a is retained. The other end of the optical fiber 25 faces a sensor such as a photocell (not shown). Further, a cylindrical cover 24a is integrally formed on the adapter 24 so as to surround the hole 22, and the end surface of the cover 24a is in close contact with a groove on the outer peripheral surface of the insulator tube 4 via a packing (not shown). In such a configuration, if a fault current flows through the energized fuse, the fusible body 3 and the display line 23 will melt. At this time, the display line 23 is always fused at a fused portion 23a having a narrow cross-sectional area, and arc light is emitted at this portion. This arc light is transmitted from the light receiving end 25a via the optical fiber 25 to a sensor (not shown) and converted into an electrical signal. Although conductive gas is generated when the display line 23 is fused, this gas does not affect other parts because the fused portion 23a is hermetically surrounded by the cover 24a. The fuse body activated by the accidental current interruption is removed from the adapter 24 by loosening the screw 19 and replaced with a new one. In the above configuration, since there is no mechanical moving part, it is not necessary to maintain the operating spring in a compressed state by the indicator line 23, and the wire diameter of the indicator line 23 can be reduced. As a result, the minimum operating voltage of the display line 23 can be lowered than in the past, and, for example, a fuse used in parallel with a semiconductor element to protect it can also have an operation display function. Furthermore, the vibration resistance of the blowout display device is improved and the reliability of the fuse is increased. Furthermore, by transmitting the signal through an optical fiber, there is an effect that insulation from the main circuit potential of the fuse is ensured.

【Effect of the invention】

According to this invention, by detecting the arc light when the display wire is fused and converting it into an electrical signal, it is possible to eliminate mechanical load on the display wire, reduce the minimum operating voltage, and reduce vibration. reliability against shocks and shocks.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of a fuse equipped with the device of the present invention, FIG. 2 is an enlarged view of the B part thereof, and FIG.
FIG. 4 is a vertical sectional view of a fuse equipped with a conventional device, and FIG. 5 is an enlarged view of part A of the fuse. 3... Fusible body, 4... Insulator tube, 23... Fusible wire for fusing display, 23a... Fusing part, 25... Optical fiber. Figure 4 8 Figure 5 Cyst stem

Claims (1)

[Claims] 1) In a fuse in which a fusible body and a fusible wire for blowout indication are stretched inside an insulator tube, a part of the fusible wire for blowout indication is formed with a fusing part that blows out before the other part, and this fusing part 1. A fuse blowout display device, characterized in that a means for detecting arc light when the fuse blows is provided in the vicinity thereof.