JPH0117081Y2 - - Google Patents

Description

[Detailed description of the invention] Purpose of the invention (industrial application field) This invention relates to a wire fuse connected to a drop-in line of a power distribution line.

(Prior art) In order to indicate whether the fuse is broken or blown in a conventional electric wire fuse, the insulating tube has a double structure, and an indicator line made of a high resistance wire is placed in the insulating inner tube so as to be parallel to the entire fusible part. It has been proposed to change the color of the display film due to the heat generated by the display line when the fuse is wound or cut off or blown, thereby indicating that the fuse is cut or blown.

(Problem that the invention aims to solve) However, with this type of wire fuse, the fusible part may be mechanically disconnected, or the fault point may recover immediately after being fused or disconnected due to surge current, etc., and the display line may If a small current flows through the display wire without causing it to melt, the display wire will heat up at a high temperature, and as a result,
There was a risk that the insulating tube would be damaged due to uneven heat and deformation.

Structure of the invention (Means for solving the problem) This invention was made to solve the above problem, and the electric wire fuse of this invention has a pair of connecting terminals at both ends of a transparent insulating tube. In an electric wire fuse, a fusible body that contributes to interrupting small currents and a fusible body that contributes to interrupting large currents are connected in series at the inner end of the connection terminal. is arranged in an insulating inner cylinder filled with an arc-extinguishing agent, and the fusible body that contributes to small current interruption is arranged so as to be visible from the outside, and in parallel with the fusible body that contributes to large current interruption. The fusible body that contributes to interrupting small currents is a resistance wire connected in series that is placed between both ends of the inner cylinder, and whose tip is placed on the inner end side of the inner cylinder, and is made of an insulating material. The gist is that the end of the resistance wire that is locked to the locking member and extends from the locking member is a tensile strength section, and that the display body made of a spring is held in a compressed state at the tip of the resistance wire via the receiving member. That's what it does.

(Function) With the above configuration, when a small current flows between the connection terminals due to an overload or the like, the fusible body that contributes to interrupting the small current is fused, and the disconnection of the fusible body can be confirmed from the transparent insulating tube, and When the metal vapor that is sometimes generated adheres to the inner surface of the insulating cylinder, a small current interruption indication is performed. Furthermore, when a large current flows between the connection terminals due to a short circuit or the like, the fusible material that contributes to interrupting the large current is fused, and immediately after the melting, the resistance wire is also fused, and the display body expands to indicate the interruption of the large current. .

(Embodiment) An embodiment embodying this invention will be described below with reference to FIGS. 1 to 3.

The insulating tube 1 is made of transparent synthetic resin, and cylindrical support tubes 2, also made of synthetic resin, are fitted onto the inner peripheral surfaces of both ends thereof and fixed with adhesive.
A pair of connection terminals 3 and 4 are provided in the center of the support tube 2.
is inserted. A pair of protective covers 5 made of synthetic resin are fitted onto both ends of the insulating cylinder 1 and fixed to the insulating cylinder 1 with an adhesive. A doughnut-shaped gap is formed between the cover 5, the support tube 2, and the connection terminals 3 and 4, and the gap is filled with silicone rubber 6 and adhesively sealed to prevent rainwater from entering. There is.

A pin 7 is inserted between the protective cover 5 and the support tube 2 in the connection terminals 3 and 4 in the diametrical direction of the support tube 2, and prevents the connection terminals 3 and 4 from coming off from the insulating tube 1. It is being

An inner cylinder 8 made of an insulating material is fitted inside the insulating cylinder 1 on the side of one of the connection terminals 3. The outer end opening of the inner cylinder 8 is sealed by an insulating plate 9, and the inner end opening is sealed by an electrode plate 10. A cap-shaped connecting fitting 11 is attached to the center of the electrode plate 10 and is electrically connected to the electrode plate 10. As described above, the storage chamber surrounded by the inner cylinder 8, the insulating plate 9, and the electrode plate 10 is filled with an arc extinguishing agent 12.

One end of a fusible body 13 made of a silver wire or the like as a large current interrupting part is connected to the inner end of one of the connection terminals 3 via the insulating plate 9 by caulking or the like, and the other end of the fusible body 13 is connected to the above-mentioned connection. It is connected to the metal fitting 11. The fusible body 13 is preferably made of a metal that has excellent interrupting properties, has a short interruption time, and generates a small amount of gas, and the fusible body 13 allows the metal to melt when a large current above a certain level flows, such as in a short circuit. ing.

One end of the display resistance wire 14 is connected to the outer circumference of the inner end of the connection terminal 3 by caulking or the like, and is introduced into the inner cylinder 8 through the insulating plate 9 so as to be separated from the fusible body 13. There is. The other end of the resistance wire 14 is fixed by being fixed to a locking member 15 attached to the inner surface of the other electrode plate 10 by adhesive or the like. Furthermore, the resistance wire 14 is connected to the locking member 15
A tensile strength portion 16 is formed to be loosely inserted into the through hole 10a of the electrode plate 10 via the through hole 10a of the electrode plate 10. Note that the locking member 15 is made of an insulating material, and is designed to ensure that it is cut at the tensile strength portion 16 as well.

One end of a bamboo spring 17 is fitted into the through hole 10a of the electrode plate 10 and is electrically connected to the electrode plate 10. Also, bamboo shoot spring 1
A cap-shaped receiving member 18 is attached to the other end of the resistance wire 14, and the tip of the resistance wire 14 is engaged with the central portion of the inner surface of the receiving member 18 while the bamboo spring 17 is in a compressed state. The bamboo shoot spring 17 and the receiving member 18
The display body 19 is constituted by these.

That is, in a normal state, the entire display body 19 is pressed against the outer end surface of the electrode plate 10 by the biasing force of the bamboo spring 17.

The fusible body 20 as a small current interrupting part is the electrode plate 10
One end thereof is connected to the connecting fitting 11 exposed from the connecting fitting 11 by brazing such as soldering or caulking. The other end of the fusible body 20 is connected to a connecting conductor 21 connected to the inner end of the other connecting terminal 4 via a cap-shaped connecting fitting 22 by brazing such as soldering or caulking. .

The fusible body 20 is made of a low melting alloy or the like, and is designed to melt when an overcurrent such as an overload current flows for a certain period of time or more.

Therefore, under normal conditions, connection terminal 3 → fusible body 1
3 → Connection fitting 11 → Fusible body 20 → Connection fitting 22 →
A main current path from the connecting conductor 21 to the connecting terminal 4 and a shunt path from the connecting terminal 3 to the resistance wire 14 to the tensile strength section 16 to the display body 19 to the electrode plate 10 (the actual current capacity is extremely small) are formed.

Next, the operation of the electric wire fuse configured as described above will be explained.

Now, when an overcurrent such as an overload flows between the connecting terminals 3 and 4 for a certain period of time or more, one of the fusible bodies 20 will melt, but at this time, the metal vapor of the fusible body 20 will be transferred to the insulating cylinder 1.
It adheres to the inner surface of the fuser member 20 to display a small current cut-off display, and the disconnection state of the fusible member 20 can be confirmed through the transparent insulating cylinder 1.

Further, when a large current flows between the connecting terminals 3 and 4 due to a short circuit or the like, the fusible body 13 is fused and immediately thereafter the resistance wire 14 in the inner cylinder 8 is also fused. In this case, the resistance wire 14
The fusing occurs not only in the inner cylinder 8 but also in the tensile strength part 16.
Since the entire display including the display body generates heat and melts at several locations almost simultaneously, the display body 19 is opened and its bamboo spring 17 is extended (see FIG. 3), thereby indicating a large current cutoff.

When the display body 19 is displayed in this manner, it can be confirmed through the insulating cylinder 1.

Note that even if the fault point is recovered and a small current flows without the resistance wire 14 being fused, the resistance wire 14 and the fusible body 20 as a small current interrupting part are connected in series, so the resistance wire 14 The fusible body 20 is fused due to the heat generated. As a result, the electric path is completely cut off, and the resistance wire 14 is prevented from continuing to generate heat for a long time. Therefore, unlike the conventional case, the insulating tube 1 is not exposed to high temperature heat generation for a long period of time until the resistance wire 14 melts, and there is no arc extinguisher 12 or Since the inner cylinder 8 is interposed and the insulating cylinder 1 does not come into direct contact with the resistance wire 14, uneven heat breakdown will not occur.

Next, a modification of the above embodiment will be explained with reference to FIG.

In this modification, an insulating plate 23 is provided as a locking member in place of the electrode plate 10 provided on the inner end side of the inner cylinder 8, and the other end of the display resistance wire 14 is connected to the through hole 23a of the insulating plate 23. It is inserted and fixed by being bonded with an adhesive 24. The tensile strength portion 16 of the resistance wire 14 led out from the through hole 23a is in a state where the bamboo shoot spring 17 is compressed with respect to the other end of the bamboo shoot spring 17 whose one end is electrically connected to the connecting fitting 11 by brazing or the like. This differs from the previous embodiment in that it is fixed at the .

The effects of this modification are the same as those of the previous embodiment.

(Effects of the invention) As detailed above, this invention allows the insulating tube to become biased even when the fault point recovers immediately after interruption, or when the wire is mechanically disconnected and a small current flows without the display wire melting. There is no risk of thermal breakdown, and when a small current is interrupted, metal vapor from the small current interrupting part adheres to the inner surface of the insulating tube, indicating a small current interrupt, and furthermore, when a large current is interrupted, This is an excellent invention for industrial use because the display body can perform a display operation to indicate a large current cutoff.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment embodying this invention, FIG. 2 is a cross-sectional view of the display body, FIG. 3 is an explanatory diagram showing the display body in a display operation state, and FIG. The figure is a sectional view of a main part of the second embodiment. 1... Insulating tube, 2... Support tube, 3... Connection terminal, 4... Connection terminal, 5... Protective cover, 8...
Inner cylinder, 9... Electrode plate, 10... Electrode plate, 11...
Connection fitting, 12... Arc extinguishing agent, 13... Fusible material, 1
4... resistance wire, 15... locking member, 16... tensile strength part, 17... bamboo shoot spring, 18... receiving member,
19... Display body, 20... Connection conductor, 21... Connection fitting, 22... Connection fitting, 23... Insulating plate (locking member), 24... Adhesive.

Claims (1)

[Claim for Utility Model Registration] A pair of connecting terminals are inserted through and attached to both ends of the transparent insulating tube, and the inner end of the connecting terminal has a fusible material that contributes to interrupting small currents and one that contributes to interrupting large currents. In a wire fuse in which a fusible body that contributes to interrupting large currents is connected in series, the fusible body that contributes to interrupting large currents is placed inside an insulating inner cylinder filled with an arc-quenching agent, and the fusible body that contributes to interrupting small currents is placed outside. A resistance wire is arranged between both ends of the inner cylinder, and is connected in parallel with the fusible body that contributes to interrupting the large current and in series with the fusible body that contributes to interrupting the small current. , its tip is placed on the inner end side of the inner cylinder and is locked to a locking member made of an insulating material, and the tip of the resistance wire extending from the locking member is used as a tensile strength section; An electric wire fuse characterized in that a display body made of a spring is held in a compressed state via a receiving member.