JPS58140948A - Fuse - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the small current breaking performance of a fuse having a low melting point portion and an arc-extinguishing tube for cutting off a relatively small current in a part of the fuse element.

The structure of a conventional fuse is shown in Figure 1.

In the figure, the C1 element (3) is wound spirally at equal pitches around a winding core (4), which is generally a porcelain insulator, and both ends are electrically connected to a metal intermediate terminal (6). It is connected to C. This core (4) is an insulating tube (2) made of porcelain etc.
The intermediate terminals (6) at both ends are electrically connected to the caps (1), which serve as external terminals, through screws (7), and both ends of the insulation n (2) are closed by the caps (1). The space between the winding core (4) and the insulating cylinder (2) is filled with arc extinguishing agent (5). Approximately in the center of element (3), as shown in FIG. 2, there is a low #t! An I1 point part (9) is provided, and its periphery is covered with an arc-extinguishing tube (8). Both ends of the tube (8) are provided with plugs (C) to prevent the arc extinguishing agent 15) from entering.

When a relatively large fault current such as a short circuit current flows through this fuse, the element (3) instantly melts over its entire length and fires, corresponding to the element length L1 + L3 at both ends other than the tube (8). generates arc pressure,
Cut off the fault current. The element inside the tube (8) will also fire instantly, or the arc extinguishing agent (5) will be inside the tube (8).
) and no carbon, the arc voltage is low and does not contribute much to interrupting large currents. - If a relatively small fault current, such as an overload current, flows through this fuse for a long time, the element (3) will become hot due to Joule heat, and will eventually melt from the low melting point part (9) of the element. The fault current is cut off in the 'C1 tube by the arc-extinguishing gas caused by the decomposition of the tube (8) by the arc energy.

However, when a small fault current is interrupted, the full voltage is applied only to a very small part of the element that is fired from the low melting point part (9), so as the rated voltage of the fuse increases, the arcing time becomes longer. Become. Furthermore, when the arc extends to one turn of the element, the full voltage is applied to the winding pitch dimension Pl of the element, so if dimension 21 is insufficient, dielectric breakdown will occur on the surface of the winding core (4), making it impossible to shut off. 'C put away. As shown in Figure 8, in order to cut off the current for a long time with a small current, it is necessary to increase the winding pitch P of the element as the rated voltage increases, but the fuse as a whole also becomes very large and expensive. I put away things and summer C.

This invention achieves high voltage and small current breaking performance by making the winding pitch of the element including the low line I point in the part sealed with the arc-extinguishing tube larger than the winding pitch of the element in other parts. This provides an excellent, compact and inexpensive fuse.

The structure of the fuse link according to the present invention is shown in FIG. The basic components are the same as the conventional one shown in Figure 1, but
The element (3) is wound so that the winding pitch P2 of the part sealed with the tube (8) on the core (4) is larger than the winding pitch P3 of the part other than the part sealed with the tube (8). That is, when the fuse dimensions such as the element (3) and other components are all the same, the element winding pitch has the following relationship.

P22\Pl>P3...fl) Here, the element at the winding pitch of 23 contributes only to cutting off large currents, and at large currents, the work force is instantaneously generated over the entire length. The voltage sharing of the elements in each turn of arc C1 becomes equal, and C becomes much smaller than in the case of small current breaker, so the winding pitch P3 is the same as the winding pitch P2 of the small current breaker.
can be made smaller as in formula C1(1).

Table 1 shows an example of the effects of the present invention.

As is clear from the table, according to the present invention, although the external dimensions and element dimensions are the same as the conventional ones, the small current interrupting performance is improved from 48.6 A for 1.04 seconds to 16.7 A for 1.04 seconds. 4.816 seconds or more, and a small and inexpensive fuse with a wide small current protection area can be manufactured.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional fuse, Fig. 2 is a detailed view of the fuse element expanded and shown in C, Fig. 3 is a diagram of the element winding pitch and voltage characteristics that can be cut off, and Fig. 4 is an example of an embodiment of the present invention. FIG. In the figure, °r, (3) is the element, (5) is the arc extinguisher,
(8) is a tube, and (9) is a low melting point part. In addition, the same reference numerals in each figure indicate the same or similar parts. Relationship with the case of the person making the amendment Patent applicant 5, 111J Correct subject matter (1) Column 6 of the detailed explanation of the invention in the specification, contents of the amendment (1) The table on page 6 of the specification is corrected as shown in the attached sheet. do. (2) Change “4.816 seconds” on page 7, line 4 of the specification to “4,
816 seconds,” he corrected. 7. List of attached documents (1) One or more documents stating the table on page 6 of the amended specification

Claims (1)

[Claims] (1) Provide a low secondary point part in a part of the element, IM the low melting point part and its vicinity with a tube having arc-extinguishing properties,
The above element is spirally wound.'C1 The element has an arc extinguishing agent around it.'C1 The element other than the one sealed with the tube has a good pitch of the part of the fuse element sealed with the tube. A fuse characterized by having a winding pitch larger than that of