JPS6239577Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to fuses such as power fuses such as current limiting fuses and vacuum fuses, and electric wire fuses. More specifically, the present invention relates to a fuse that displays a blown indication when the fuse is blown.

Prior Art In a conventional fuse, for example, a current-limiting fuse, a fuse element wound around an insulating core inside the fuse insulating cylinder melts when a fault current such as a short circuit current or an overload current passes through it.
As a result, a structure has been proposed in which a high resistance wire connected in parallel with a fuse element between both electrodes provided at both ends of an insulating cylinder and disposed within an insulating core is fused by Joule heat.

When this high resistance wire melts,
The compression spring of the fusing display device, which was restrained by the high-resistance wire in the insulated core, operates and causes the display to protrude, or the pyrotechnic agent in the fusing display reacts to cause the display to protrude. I was trying to display the following information.

In these devices, the insulating tube that makes up the fuse is made of opaque porcelain, so this is an unavoidable measure, but depending on factors such as the selection of high resistance wire, usage conditions, and manufacturing variations, the fuse may be displayed. However, there were cases where the system did not fully fulfill its role, causing inconvenience. In addition, in the above-mentioned fusing display device, a high resistance wire must be installed between both electrodes, and furthermore, assembly work such as properly holding the compression spring that pushes out the display body in a compressed state is troublesome. However, there was a problem with the structure being complicated. Furthermore, when using an pyrotechnic agent, not only is there a problem with workability such as moisture absorption, but it is also necessary to pay special attention to work safety.

On the other hand, in the case of vacuum fuses, it is difficult to assemble a fusing indicator such as an upper limit flow fuse to the vacuum fuse itself, so conventionally an indicator fuse was attached to the fuse holder in parallel with the vacuum fuse. was. Therefore, it is necessary to separately prepare a display fuse, which poses problems of complicating the structure, securing space, and increasing manufacturing costs.

By the way, the ceramic used for the insulating tube is made by sintering powder mainly composed of metal oxides at high temperatures, and its structure is composed of fine crystal grains, and because light is scattered at the grain boundaries, it is generally close to white in color. It is an opaque body.

However, in recent years, as ceramic manufacturing technology has improved and research has progressed on additives that make fine powders a solid solution, transparent ceramics that are dense and suppress the scattering of light at grain boundaries have been developed.

A typical example of such transparent ceramics is PLZT ceramics. PLZT ceramics maintains ferroelectricity and is transparent to visible and infrared light, so electro-optic effects can be seen.
Further, by applying an electric field, the anisotropic orientation of the dielectric domains is aligned or disordered, thereby producing a light scattering effect.

Purpose of the invention Therefore, this invention attempts to solve the above problem by using transparent ceramics with an electro-optic scattering effect.The purpose is completely different from that of conventional fusing display devices. Our goal is to provide fuses with functions.

Structure of the invention The fuse of this invention has an insulating tube made of transparent ceramics that maintains ferroelectricity and has a light scattering effect when an electric field is applied, electrodes are arranged at both ends of the insulating tube, and both electrodes are placed inside the insulating tube. A fuse element is arranged to electrically connect between the two.

Embodiment A first embodiment in which this invention is embodied in a current limiting fuse will be described below with reference to FIGS. 1 and 2. The insulating cylinder 1 is made of transparent ceramics having an electro-optic scattering effect.

In this embodiment, PLZT ceramics are used as the transparent ceramics. This PLZT ceramic is a solid solution in which Pb in PbTiO3−PbZrO3 is partially replaced with La, and its composition is (Pb1−xLax).
It is written as (Zr1−yTiy)O3 and is expressed by the components (x/1−y/y) of La, Ti, and Zr in the above formula, for example
It is shown as PLZT (9/65/35). In this example, it is colorless and transparent, almost like glass.
PLZT (9/65/35) is used.

When a voltage is applied to both ends of this PLZT ceramic, it produces a light scattering effect that depends on the alignment or disorder of the anisotropic orientation of the dielectric domains. That is, when no voltage is applied, the insulating cylinder 1 is transparent so that the inside can be seen from the outside, and when a voltage is applied, it becomes opaque due to light scattering.

A pair of electrodes 2 are fitted onto both ends of the insulating tube 1 in a sealed manner.
An insulating core 3 is arranged between them. Insulated core 3
A fuse element 4 having both ends connected to both electrodes 2 is spirally wound around the outer periphery of the fuse element 4 .
The fuse element 4 includes a silver wire 5 that contributes to interrupting high-magnification current, a low-melting alloy 6 connected in series to the silver wire 5, and a portion covered by an arc-extinguishing tube 7 that contributes to interrupting low-magnification current. It is made up of A space surrounded by the insulating cylinder 1 and the insulating core 3 is filled with arc-extinguishing sand 8.

Now, when the current-limiting fuse configured as described above is attached to the fuse holder (not shown) and a normal current is flowing, the two electrodes of the insulating tube 1 are at the same potential, so a potential difference occurs. Since it is not present, it is in a transparent state and displays a normal state. If a low magnification current flows in this state due to overload, etc.,
The silver wire 5, which has a high melting point, does not melt, but only the low-melting alloy 6, which has a low melting point, fuses and arcs, and the arc-extinguishing tube 7 is thermally decomposed by the heat generated by the arc, and arc-extinguishing gas having negative electrical characteristics is released. The arc is generated and the arc is extinguished.

When the low-melting alloy 6 is fused as described above, a voltage between electrodes is applied to both ends of the insulating tube 1, so that the insulating tube 1 changes from a transparent state to an opaque state to display a fused state. When the current-limiting fuse that is displaying this blowout indication is removed from the fuse holder, it becomes a no-voltage state and no voltage is applied to both ends of the insulating tube 1, so the insulating tube 1 returns from an opaque state to a transparent state and is insulated. The inside can be visually recognized through the tube 1.

In addition, when a high-magnification current flows due to a short circuit, etc., the entire fuse element 4 fuses and fires at the same time, and the metal vapor is diffused into the arc-extinguishing sand 8 and cooled, and a caterpillar-like high-resistance element is formed. formed and rapidly current-limited and cut off. Then, in the same way as when the low magnification current passes through, a voltage is applied to both ends of the insulating tube 1, so that the insulating tube 1 changes from a transparent state to an opaque state, thereby displaying a fusing state. When the current-limiting fuse that is displaying this blown-out indication is removed from the fuse holder, no voltage is applied to both ends of the insulating tube 1, so the insulating tube 1 returns from an opaque state to a transparent state, and the inside of the insulating tube 1 is The changed state of the arc-extinguishing sand 8 can be visually recognized.

When the low-magnification current passes, the arc-extinguishing sand 8 does not contribute to current interruption, so no change occurs, but when the high-magnification current passes, the arc-extinguishing sand 8 contributes to current interruption and a change occurs, so the change is absorbed by the insulating tube 1. It can be visually recognized from the outside, and thereby it is possible to immediately judge whether to interrupt the low-magnification current or the high-magnification current without destroying the sample.

Therefore, there is no need to assemble a conventional fusing display device, the number of parts of the current limiting fuse can be reduced, and the assembly work can be simplified.

Furthermore, the electro-optical properties of PLZT ceramics can be freely adjusted by controlling the composition, and since they are ceramics, it is easy to make them into any size.

Next, a second embodiment embodied in a vacuum fuse will be described with reference to FIG.

The insulating tube 10 serving as the insulating tube of the vacuum fuse is made of transparent ceramics having an electro-optic scattering effect as in the first embodiment.
Cover plates 11 made of metal plates such as copper are attached to both ends of the insulating tube 1 by brazing or the like.
The internal space 12 of 0 is maintained in a vacuum state.
Electrodes 13 are supported through the center portions of both lid plates 11, and arc runners 14 are provided at opposing inner ends of both electrodes 13. A fuse element 15 is stretched between both arc runners 14, and when an overcurrent flows between both electrodes 13, this fuse element 15 is blown out.

A cylindrical shield 16 is disposed within the insulating tube 10 at a slight distance from its inner peripheral surface so as to surround the arc runner 14 and the fuse element 15, and the arc vapor generated when the fuse element 15 is fused is absorbed by this cylindrical shield 16. It is adapted to be attached to the inner peripheral surface of the shield 16. Note that the shield 16 is formed from a plate material such as a mesh so that the inside is visible from the outside.

Now, when this vacuum fuse is attached to a fuse holder (not shown) and a normal current is flowing, the insulating tube 10 is transparent and indicates a normal state. When an overcurrent flows between both electrodes 13 and the fuse element 15 blows out in the internal space 12 of the insulating tube 10, a voltage between electrodes is applied to both ends of the insulating tube 10, so the insulating tube 10 changes from a transparent state to an opaque state. Displays fusing. When the vacuum fuse displayed as blown is removed from the fuse holder, the voltage between electrodes is no longer applied to both ends of the insulating tube 10, and the insulating tube 10 returns to the transparent state.
The blown state of the vacuum fuse can be visually confirmed through the shield 16.

Conventionally, it was not possible to assemble a blowout display device to the vacuum fuse itself, and a separate display fuse was connected in parallel to the vacuum fuse using a fuse holder.
Therefore, the cost of a vacuum fuse with a blowout display device is high, and the fuse holder must also be configured to be able to sandwich both the vacuum fuse and the display fuse, but in this embodiment, this is not necessary and the cost is low. The structure of the fuse holder can also be simplified.

Next, the third embodiment is applied to a wire fuse and the fourth embodiment is implemented.
This will be explained according to the diagram.

An insulating support cylinder 19 is hermetically fitted into both ends of an insulating cylinder 18 made of transparent ceramics as in the first embodiment, and counter electrodes whose inner ends face each other via the support cylinder 19 are arranged. A pair of 20 are inserted. A conductive locking pin 21 whose both ends are engaged with the insulating tube 18 via the support tube 19 is inserted in a diametrical direction in a portion of the counter electrode 20 corresponding to the support tube 19 . A fuse element 22 made of a low melting alloy is connected between the inner ends of the opposing electrodes 20. A protective cover 23 is fitted onto both ends of the insulating tube 18 .

Therefore, in the normal state of this electric wire fuse, the insulating tube 18 is transparent and indicates the normal state, but when an overcurrent flows and the fuse element 22 melts, the insulating tube 18 is closed via the locking pin 21 and the counter electrode 20. Since a voltage between electrodes is applied to both ends, the transparent state changes to an opaque state and a fusing display is performed. When the wire fuse that is displayed as blown is removed from the wire, the opaque state returns to the transparent state, so that the inside of the wire fuse can be visually confirmed.

It should be noted that this invention is not limited to the above-mentioned embodiments, and may be modified as desired without departing from the spirit of this invention.

Effects of the invention As detailed above, this invention forms an insulating cylinder from transparent ceramics that maintains ferroelectricity and has a light scattering effect when an electric field is applied, electrodes are placed at both ends of the insulating cylinder, and By connecting a fuse element placed in an insulating cylinder between the electrodes, the assembly work can be simplified with a simple configuration, and after the fuse is indicated, the inside can be easily seen from the outside to confirm the fuse. The condition can also be checked, making maintenance and inspection easier. Therefore, the conventional fusing display device is no longer necessary, and the presence or absence of an abnormality and the state after the fusing can be clearly seen, and the structure is simple, leading to improved performance, as well as technical and economical benefits such as cost reduction. It has many advantages and offers great benefits to industry.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the current limiting fuse of the first embodiment of this invention, Fig. 2 is a sectional view of the main part thereof, Fig. 3 is a sectional view of the vacuum fuse of the second embodiment, and Fig. 4 is a sectional view of the vacuum fuse of the second embodiment. It is a sectional view of the electric wire fuse of an example. 1... Insulating tube, 2... Electrode, 3... Insulating core,
4...Fuse element, 10...Insulated pipe,
13... Electrode, 15... Fuse element, 1
6... Shield, 18... Insulating cylinder, 20... Counter electrode, 21... Locking pin, 22... Fuse element.

Claims (1)

[Claims for Utility Model Registration] 1. An insulating cylinder is formed from transparent ceramics that maintains ferroelectricity and has a light scattering effect when an electric field is applied, electrodes are arranged at both ends of the insulating cylinder, and both ends are placed inside the insulating cylinder. A fuse characterized by having a fuse element arranged to electrically connect between electrodes. 2. The fuse according to claim 1, wherein the insulating cylinder is made of PLZT ceramics.