JPH0125428Y2 - - Google Patents

Description

[Detailed description of the invention] This invention automatically disconnects the lightning arrester from the distribution line when it is damaged or its characteristics have deteriorated due to aging and it is no longer able to interrupt the ground voltage of the distribution line. , relates to a device for preventing grounding accidents caused by this lightning arrester.

FIG. 1 shows an embodiment of the device of the present invention.
In the figure, 1 is a disc-shaped upper metal fitting with a cylindrical protrusion 1a protruding from the center of one surface, 2 is a lower metal fitting with the same shape as the upper metal fitting 1, and 3 is the upper metal fitting 1 disposed oppositely. It is a cylindrical explosive agent held between the protrusion 1a and the protrusion 2b of the lower metal fitting 2.
The explosive material 3 is a mixture of combustible metal powder, such as magnesium, and oxides such as nitrates and chlorates, which does not absorb moisture even when left for a long period of time. Therefore, it is relatively safe to handle. Reference numeral 4 denotes an insulated resistance wire which is wound into a coil shape and has both ends electrically connected to the upper metal fitting 1 and the lower metal fitting 2, respectively, and is tightly attached to the outer peripheral surface of the explosive agent 3. This insulated resistance wire 4 has a resistance value of, for example, several ohms, and the insulated coating on the outer peripheral surface of the coil is peeled off. Therefore, the insulated resistance wires 4 are coil-wound and arranged in parallel with adjacent wires with the exposed internal resistance wires 4a kept at a constant interval, but the remaining insulated resistance wires 4b As a result, they are kept insulated against low voltages. Further, 5 is an insulating cylindrical member having male screws 5a and 5b formed on the outer peripheral surface of both ends. This cylindrical member 5 is made of an insulating material such as synthetic resin, and an annular groove 5c having a V-shaped cross section is bored in the outer circumferential surface of the intermediate portion thereof, and the vicinity thereof is a weaker strength portion 5c'. This cylindrical member 5 is positioned so that its inner corner portions at both ends are fitted into step portions 1b and 2b formed on the upper metal fitting 1 and the lower metal fitting 2. 6 is an upper metal terminal having a bowl-shaped portion 6a into which the upper metal fitting 1 is fitted and a threaded rod-shaped connecting member 6b protruding from the opposite surface;
A female thread 6a', into which the male thread 5a of the cylindrical member 5 is screwed, is formed on the inner peripheral surface of the bowl-shaped portion 6a.
Reference numeral 7 denotes a lower metal terminal having a bowl-shaped portion 7a into which the lower metal fitting 2 is fitted, and a cable attachment pipe 7b protruding from the opposite side thereof.The inner peripheral surface of the bowl-shaped portion 7a is provided with a male screw of the cylindrical member 5. Female screw 7 for screwing together 5b
a′ is formed.

In the above structure, the upper metal terminal 6 and the lower metal terminal 7 are fixed to the cylindrical member 5 with screws to form a closed container 8 in which the explosive agent 3, the insulated resistance wire 4, etc. are housed. In addition, these male screws 5
When a, 5b and female screws 6a', 7a' are screwed together, if necessary, for example, a resin adhesive (not shown) is poured into the threaded part to make the sealed structure stronger. be able to. Also, the upper metal terminal 6
and the lower metal terminal 7 are electrically connected to the upper metal fitting 1 and the lower metal fitting 2 by fitting them, respectively, and as a result, both ends of the insulated resistance wire 4 are connected to the upper metal terminal 6 and the lower metal terminal 7, respectively. electrically connected to.

The lightning arrester disconnection device C having the above structure is attached as shown in FIG. 2 or 3 using the connecting members 6b at both ends and the cable attachment pipe 7b. That is, in the case of Fig. 2, the surge arrester disconnection device C is connected between the other end of the surge arrester b, which has one end connected to the distribution line a, and the ground d, and in the case of Fig. 3, the surge arrester disconnection device C has one end connected to the ground d. It is used by being connected between the other end of the lightning arrester b connected to the ground d and the distribution line a.

The operation in this connected state is as follows.

First, to explain the operation when lightning arrester b is normal, during normal power transmission, for a predetermined transmission voltage applied to distribution line a, lightning arrester b does not operate, so no ground fault current flows to earth d. do not have. Therefore, the arrester disconnection device does not work. When an abnormally high voltage is applied to the distribution line a due to a lightning strike, etc., the lightning arrester B operates and the surge current is passed through, and at the same time, the insulated resistance wire 4 in the lightning arrester disconnection device C is exposed. The surfaces of adjacent resistance wires 4a are flash-crossed. In this case, the blasting agent 3 of the lightning arrester disconnection device is not expanded, so the lightning arrester disconnection device does not work. Therefore, a surge current flows from the distribution line a to the ground, protecting the distribution line a and electrical equipment (not shown) connected to the distribution line a. When the abnormally high voltage is absorbed by the ground d by the above operation, the earth protector b blocks the following current and returns to the normal state.

On the other hand, when lightning arrester b is damaged or its characteristics deteriorate due to aging and it is no longer able to cut off the ground voltage of distribution line a, the arrester disconnecting device C
The lightning arrester b is separated from the distribution line a or the ground d by the following operation.

When the characteristics of lightning arrester b deteriorate and it loses its ability to cut off the ground voltage, lightning arrester b and arrester disconnection device C
A ground fault current flows from the distribution line a to the ground d via the insulated resistance wire 4 between the upper metal terminal 6 and the lower metal terminal 7 . This ground fault current is the ground voltage (50 Hz or 60
Hz), and because the resistance value of the insulated resistance wire 4 is small compared to the inductance of the coil, it continuously flows through the insulated resistance wire 4. Therefore, the insulated resistance wire 4 continuously generates Joule heat, and the explosive agent 4 is gradually heated and expanded by this heat, eventually destroying the weaker part 5c' of the closed container 8. , the lightning arrester disconnection device C is divided into upper and lower parts. As a result, the insulated resistance wire 4 is cut, the lightning arrester b is separated from the distribution line a or the ground d, and the ground fault current is also cut off. In this state, the lightning arrester disconnection device C is divided into two parts, so it can be easily found when inspecting and inspecting the distribution line a for maintenance. The user then knows that the characteristics of lightning arrester b have deteriorated, and can take appropriate measures such as replacing it.

Note that the weaker strength portion provided in the airtight container is not necessarily the annular groove 5c having a V-shaped cross section as described above.
It does not have to be formed by For example, the portions can be designed as desired depending on the structure of the closed container, such as by forming the portions with a fitting structure.

In addition, in the device of the present invention, the reason why the insulated resistance wire 4 wound in a coil shape on the outer peripheral surface of the explosive agent 3 is provided with a peeled part of the insulation coating is that the distribution line a
This is to eliminate the abnormally high voltage with a steep waveform applied to the circuit. In other words, if this peeled part is not provided, the insulated resistance wire 4 wound into a coil will have a large inductive reactance against abnormally high voltage with a steep waveform, so the surge current will cause the insulated resistance wire 4 to
A high voltage is applied to the insulated resistance wire 4 wound into a coil provided between In other words, a voltage corresponding to the inductive reactance is applied to adjacent portions of each coil. That is, by peeling off the insulating coating, the exposed resistance wire 4b will flash due to the high voltage. Structurally, by peeling off the insulation coating, that part is given the role of a discharge gap. Note that the insulation coating does not necessarily need to be peeled off over the entire outer circumferential surface of the coil, but may be removed on a part of the outer circumferential surface. In short, it is sufficient to provide an exposed portion of the resistance wire 4b that communicates between the upper metal fitting 1 and the lower metal fitting 2 while maintaining a predetermined pitch interval.

As explained above, according to the present invention, a pair of metal terminals are provided at both ends, and an explosive agent and a coiled insulated resistance wire are placed in an airtight container that has a weak part at the position separating the two metal terminals. It is possible to provide a small and compact lightning arrester disconnection device. During the operation, it is completely divided into two parts, so that the separation operation is ensured.
It becomes easy to visually see that the lightning arrester has deteriorated in characteristics. Furthermore, since the insulated resistance wire is directly wound around the blasting agent, the heat generated during the cutting operation is efficiently transferred to the blasting agent, improving response characteristics. Furthermore, since the insulation coating of the insulation coating resistance wire 4 is peeled off to form a gap therein, there is no need to separately provide a gap for passing surge current, and the number of parts can be reduced.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing one embodiment of the present invention;
3 and 3 are diagrams showing different installation examples of the device of the present invention, respectively. 1... Upper metal fitting, 2... Lower metal fitting, 3... Explosive agent, 4... Insulated resistance wire, 4a... Resistance wire, 4
b... Insulating coating, 4c... Peeling part, 5... Cylindrical member, 5c... Annular groove, 5c'... Weak strength part,
6... Upper metal terminal, 7... Lower metal terminal, 8...
...Airtight container, C...Surge arrester disconnection device.

Claims (1)

[Scope of utility model registration request] A sealed container is provided with a pair of metal terminals at both ends and has a weakly strong part at the position separating both metal terminals, and a sealed container is sealed in the sealed container and expands when heated to move the sealed container along the weakly strong part. The detonating agent is electrically connected to both metal terminals at both ends, and the insulating coating on the outer peripheral surface of the coil is peeled off. A lightning arrester disconnection device comprising an insulated resistance wire.