JPH0530268Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a cylindrical cutout, and in particular to a structure that prevents secondary flash faults from occurring due to abnormal voltages such as multiple lightning strikes after cut-out.

Within the cylindrical cut-out porcelain body, a discharge fuse tube is generally held vertically with its arc outlet facing downward.

If a large current is cut off due to a short circuit, etc., this discharge type fuse cylinder extinguishes the arc by releasing metal vapor and arc-extinguishing decomposition gas from the fuse cylinder through the arc discharge port at the bottom end. The fuse cylinder instantaneously becomes depressurized due to the release action at the time of shutoff, and then a suction action occurs, so that the electrically conductive gas such as the metal vapor released once again flows back into the porcelain body. For example, it may enter the space between the inner peripheral surface of the porcelain body and the outer peripheral surface of the arc-extinguishing outer cylinder, flow upward, or become stagnant, significantly reducing the dielectric strength between the upper and lower electrodes. let

When abnormal voltage such as lightning enters in this state of reduced insulation, a secondary flash fault occurs between the upper electrode and the lower electrode, and the follow-on arc associated with this secondary flash fault can damage the porcelain or damage the fuse cylinder. This may cause accidents such as dropping the product.

This proposal relates to the configuration of a cylindrical cutout aimed at solving these problems, and an upper electrode 3 is placed on the upper part of the cylindrical porcelain body 2, which has a closed upper end and an open lower end. Lower electrodes 4 are respectively fixed at the bottom, and between the upper electrode 3 and the lower electrode 4 there is an arc-extinguishing outer cylinder 7 in a vertically elongated shape and an arc-extinguishing inner cylinder arranged concentrically at the center of the outer cylinder. The cylinder 8 is further provided with both the upper and lower electrodes 3 and 4.
On the other hand, a discharge type fuse tube 10 having an arc discharge port 18a at the lower end is connected to the porcelain main body 2 by making the upper contact 11 of the same tube removably contact the upper electrode 3 and the lower contact 17 of the same tube removably contacting the lower electrode 4. In the arc-extinguishing outer cylinder 7, an annular elastic shield 19 made of a single-cell sponge that is in close contact with the inner peripheral surface 2c of the porcelain body 2 is attached to the upper outer peripheral surface 7a' of the arc-extinguishing outer cylinder 7. It is characterized by being adhesively fixed in one piece.

An embodiment of the present invention will be described below based on FIGS. 1 to 4. 1 shows a cylindrical cutout, and as is well known, inside the cylindrical porcelain body 2 whose upper end is closed and whose lower end is open, there is a tulip-shaped upper electrode 3 on the upper part and a lower electrode 4 on the lower part. Fixed. 5 is a stress cone-shaped upper lead wire connected to the upper electrode, and 6 is a stress cone-shaped lower lead wire connected to the lower electrode.
7 and 8 are a vertically long arc-extinguishing outer cylinder provided between the upper electrode 3 and the lower electrode 4, and a short arc-extinguishing inner cylinder arranged concentrically at the center of the outer cylinder. It is made of urea or melamine resin, which sometimes generates arc-extinguishing gas. Reference numeral 9 denotes a coil spring that always urges the arc-extinguishing inner cylinder 8 downward, and when the fuse cylinder 10 is pulled out during load opening/closing, etc., the same cylinder quickly hangs down inside the arc-extinguishing outer cylinder 7 and both cylinders are closed. A thin arc-extinguishing section is formed between the two, and the arc generated between the upper contact 11 of the fuse cylinder and the upper electrode 3 when separated (load switching/closing) is guided to this narrow arc-extinguishing section and extinguished. . Reference numeral 8a indicates a guide portion of the arc-extinguishing inner cylinder, and reference numeral 2a indicates a guide protrusion of the porcelain body.

Further, 12 is a buffer ring made of synthetic resin provided on the lower inner step of the porcelain body, 13 is a lower cover made of synthetic resin fixed to the opening 2b at the lower end of the porcelain body, and 14 is the opening 13a of the lower cover. A lid made of synthetic resin that can be freely inserted and closed, 15 is an engaging piece for holding the lid, and 16 is a connecting string that connects the lid and the lower cover.

10 also connects a cylindrical upper contact 11 to an upper electrode 3.
Furthermore, it is a discharge type fuse tube in which the lower contacts 17 are brought into contact with the lower electrodes 4 and held vertically within the porcelain body, and the lower end thereof, that is, the lower end of the insulating tube 18, is provided with an arc discharge port 18a. 20
1 is a fuse in which the upper terminal is connected to the upper contact, the lower lead wire 20a is led out from the arc discharge port 18a, and the tip thereof is folded back and connected to the wire clamping portion 17a of the lower contact 17;
9 is designed to close the upper part of the gap 〓g formed between the inner circumferential surface 2c of the porcelain main body and the outer circumferential surface 7a of the arc-extinguishing outer cylinder 7 to prevent backflow of conductive gas when shutting off. The shield is an annular elastic shield made of a single-cell sponge, which is integrally fixed with an adhesive to the outer circumferential surface 7a' of the upper end of the arc-extinguishing outer cylinder, so there is relatively little variation in dimensions. It is made from a single-cell sponge that is flexible enough to firmly adhere to the inner circumferential surface 2c of a large porcelain body, has a large restoring force, and has insulation properties.

As described above, in the cylindrical cutout of the present invention, a ring-shaped elastic shield made of a single-cell sponge that is highly flexible and has a large restoring force is bonded to the outer peripheral surface of the upper end of the arc-extinguishing outer cylinder to prevent gas backflow. Since it is fixed, it can be reliably brought into close contact with the inner circumferential surface of the porcelain, which has large dimensional variations, and as a result, it is possible to reliably prevent secondary flash faults due to backflow of gas after shutoff. In addition, the above-mentioned elastic shield is highly flexible, and even if the fuse cylinder is inserted from below and collides with the lower end of the arc-extinguishing outer cylinder, the movement of the lower end of the cylinder is not particularly restricted. It has features such as the cylinder tilting smoothly and not interfering with insertion work.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of a cylindrical cutout showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the upper part of the cylindrical cutout seen from the side in FIG.
FIG. 3 is a cutaway view of the main part of the arc-extinguishing outer cylinder in which the shield is adhesively fixed, and FIG. 4 is a plan view of FIG. 3. 1 ...Cylindrical cutout, 2...Porcelain body, 2
c... Inner peripheral surface, 3... Upper electrode, 4... Lower electrode, 7... Arc extinguishing outer cylinder, 7a'... Outer peripheral surface of upper end, 8
... Arc-extinguishing inner cylinder, 10 ... Release type fuse cylinder, 11
...Top contact, 17...Bottom contact, 18a...
...Arc discharge port, 19...Elastic shield.

Claims (1)

[Scope of utility model registration request] Inside the cylindrical porcelain body 2 having a closed upper end and an open lower end, an upper electrode 3 is fixed to the upper part and a lower electrode 4 is fixed to the lower part, and between the upper electrode 3 and the lower electrode 4. is equipped with a vertically long arc-extinguishing outer cylinder 7 and an arc-extinguishing inner cylinder 8 arranged concentrically at the center of the outer cylinder 7, and further includes an arc-extinguishing inner cylinder 8 arranged concentrically at the center of the outer cylinder 7, and further includes an arc extinguishing cylinder 8 at the lower end with respect to both the upper and lower electrodes 3, 4. A discharge type fuse tube 10 having a discharge port 18a is connected to the upper contact 1 of the same tube.
1 to the upper electrode 3 and the lower contact 17 to the lower electrode 4 in a removable manner and held vertically within the porcelain body 2,
The arc-extinguishing outer cylinder 7 has a cylindrical shape, in which an annular elastic shield 19 made of a single-cell sponge, which is in close contact with the inner peripheral surface 2c of the porcelain body 2, is integrally adhesively fixed to the outer peripheral surface 7a' at the upper end of the arc-extinguishing outer cylinder 7. Cut out.