JPH0312202Y2 - - Google Patents

Description

[Detailed description of the invention] Purpose of the invention (industrial application field) This invention relates to a vacuum fuse used in high and low voltage distribution lines.

(Prior Art) In recent years, as the demand for electric power has increased, the capacity of power distribution lines has been increased, and vacuum fuses have been used as devices to protect these lines. However, although vacuum fuses have a larger capacity than general-purpose power fuses, they are made lighter and smaller in order to take advantage of their characteristics, and as a result, there is insufficient space to incorporate a blowout display that can visually confirm the fuse blowout status.

(Problem that the invention aims to solve) Therefore, currently, in the event of an accidental power outage, in order to determine whether the vacuum fuse has blown, it is necessary to remove the vacuum fuse from the equipment or mounting bracket and check for continuity. This caused inconvenience in terms of maintenance and inspection.

This invention was made in order to solve the above-mentioned problems, and the object is to provide a vacuum fuse equipped with a blowout display device that allows one to easily check whether or not the vacuum fuse has blown.

Structure of the device (Means for solving the problem) This device connects a pair of cylindrical insulating spacers with a shield case to form a vacuum container, and inserts a pair of electrodes from both ends of the vacuum container. In a vacuum fuse in which the inner ends are arranged facing each other and a fuse element is connected between the inner ends, one of the insulating spacers is made of barium titanate ceramic doped with a small amount of rare earth elements such as yttrium, antimony, and lanthanum. A temperature indicating material that irreversibly changes color due to temperature rise is placed on its outer surface, and a resistance value greater than that of the fuse element is provided between the power supply side and the load side with the other insulating spacer in between. The gist of this is that a resistance wire is connected.

(Function) With the above configuration, when a fault current flows through the vacuum fuse due to a short-circuit accident or the like, the fuse element first melts. Then, the current flows through one of the insulating spacers made of barium titanate ceramic doped with a small amount of rare earth elements such as yttrium, antimony, and lanthanum, which causes the insulating spacer to rapidly heat up and increase its resistance. The temperature indicating material placed on the outer surface of the fuse irreversibly changes color due to the heat, indicating that the fuse has blown.
Further, since current flows through the resistance wire through the insulating spacer and the shield case, the resistance wire also melts and the circuit is completely cut off.

(Example) An example embodying this invention will be described below with reference to the drawings.

In the vacuum vessel 1, a pair of insulating spacers 2 and 3 are connected by a cylindrical shield case 4 made of metal, and end plates 5, also made of metal, are provided at opposite ends of the insulating spacers 2 and 3. 6 is formed in a sealed manner, and the internal space A of the container 1 is maintained in a vacuum state. The insulating spacer 2 on the power supply side is made of barium titanate ceramic, which is made into a semiconductor by doping a small amount of rare earth elements such as yttrium, antimony, and lanthanum, and serves as a resistor whose resistance value increases as the temperature rises. fulfill. This barium titanate ceramic is
PTCR (positive temperature coefficient)
This barium titanate ceramic is hereinafter referred to as a PTCR heating element. Further, the insulating spacer 3 on the load side is made of ordinary ceramic.

A pair of conductors 7 and 8 are supported through the center portions of both end plates 5 and 6, respectively, and electrodes 9 and 10 are provided at mutually opposing inner ends, respectively. A fuse element 11 is stretched on the inner end surfaces of both the electrodes 9 and 10, and both the conductors 7 and
When an overcurrent flows between the fuse elements 8 and 8, the fuse element 11 is blown out.

On the outer peripheral surface of the insulating spacer 2, there is a temperature-indicating paint 1 as a temperature-indicating material that irreversibly changes color due to temperature rise.
2 is applied. Also, the other insulating spacer 3
A resistance wire 13 having a resistance value greater than that of the fuse element 11 is arranged along the inner surface in the axial direction thereof, and both ends thereof are connected to the end of the shield case 4 and the end plate 6. . That is, a series circuit is formed consisting of the insulating spacer 2 made of the PTCR heating element, the shield case 4, and the resistance wire 13, and the series circuit includes the end plate 5,
6 in parallel to the series circuit of the electrodes 9, 10 and the fuse element 11.

Now, the operation of the vacuum fuse configured as described above will be explained.

Now, if a short-circuit accident or the like occurs in the electric circuit in this vacuum fuse and a fault current such as an overcurrent flows through the fuse element 11, the fuse element 11 will melt. Then, the current flows through the series circuit consisting of the insulating spacer 2 consisting of the PTCR heating element, the shield case 4, and the resistance wire 13, so the PTCR
The insulating spacer 2, which is a heating element, suddenly generates heat and its resistance increases, and the hot paint 12 applied to the outer peripheral surface of the insulating spacer 2 irreversibly changes color due to the heat, indicating that the fuse has blown. Further, since a current flows through the resistance wire 13 through the insulating spacer 2 and the shield case 4, the resistance wire 13 is fused and the circuit is completely cut off.

The above operations are performed with almost no time lag when the fault current flows, so there is no damage to equipment on the power distribution line.

With such a simple structure, blowing of a vacuum fuse can be accurately indicated, which greatly facilitates maintenance and inspection on actual lines, and has the advantage of widening the scope of application. Furthermore, since the vacuum fuse is used indoors, the temperature indicating material that can be used here is less susceptible to deterioration due to environmental conditions such as ultraviolet rays, wind and rain, and can be used reliably for a long period of time.

It should be noted that this invention is not limited to the above-mentioned embodiments, and may be arbitrarily modified without departing from the spirit of this invention, such as using a temperature indicating material other than temperature indicating paint.

Effects of the device As detailed above, this device has a very simple structure, and the presence or absence of melting can be easily seen from the outside. It has excellent effects.

[Brief explanation of the drawing]

The figure is a sectional view of a vacuum fuse according to an embodiment of this invention. 1... Vacuum container, 2... Insulating spacer, 3...
Insulating spacer, 4... Shield case, 9, 10
... Electrode, 11 ... Fuse element, 12 ...
...Temperature indicating material (temperature indicating paint), 13...Resistance wire.

Claims (1)

[Claims for Utility Model Registration] A pair of cylindrical insulating spacers 2 and 3 are connected by a shield case 4 to form a vacuum vessel 1, while the opposite ends of the insulating spacers 2 and 3 are The vacuum container 1 is sealed by forming metal end plates 5 and 6, and a pair of conductors 7 and 8 are inserted into both ends of the vacuum container 1, and a pair of conductors 7 and 8 are inserted into the inner ends of the conductors 7 and 8. In a vacuum fuse in which a pair of electrodes 9 and 10 are arranged facing each other and a fuse element 11 is connected between the electrodes 9 and 10, one of the insulating spacers 2 and 3 is made of a rare earth element such as yttrium, antimony, or lanthanum. It is made of barium titanate-based ceramic doped with a small amount of carbon dioxide, and a temperature indicating material 12 that irreversibly changes color due to temperature rise is arranged on its outer surface. A vacuum fuse characterized in that a resistance wire 13 having a resistance value greater than that of the fuse element 11 is connected between the end plate 6 on the insulating spacer 3 side.