JPH0216554B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention is intended for use when equipment such as lightning arresters connected to distribution lines has deteriorated in characteristics due to damage or aging and is no longer able to maintain an insulating state. This relates to a disconnection device that automatically disconnects from power distribution lines to prevent grounding accidents caused by this device.

(b) Prior Art A conventional type of the above-mentioned separating device is described in Japanese Patent Publication No. 49-42298, which was previously filed by the present applicant. The structure of this conventional device is as shown in FIG. That is, in a cylindrical case 2 made of an insulator and having a groove 1 formed in a part of the inner circumferential wall, a gap g consisting of an upper electrode 3 and a lower electrode 4, a resistor 5 connected to both ends of the gap g, and Explosive 6 heated by resistor 5
an upper terminal 7 whose openings at both ends are electrically connected to the upper electrode 3 and the lower electrode 4, respectively.
and is closed by the lower terminal 8. This disconnection device a is connected between the power distribution line L and the ground E in series with the lightning arrester b, as shown in FIG. With this connection, the disconnection device a may be connected to the power distribution line L side as shown by the solid line, or may be connected to the earth E side as shown by the broken line.

In this connected state, when a surge voltage occurs on the distribution line L due to a lightning strike, lightning arrester B operates,
A discharge occurs in the gap g and absorbs the surge voltage. This causes the power distribution line L to return to normal voltage.

However, if the performance of the lightning arrester b has deteriorated due to aging or some other cause, a leakage current will flow to the ground E due to the normal ground voltage applied between the distribution line L and the ground. However, the temperature inside the cylindrical case 2 gradually rises due to the Joule heat generated when these currents flow through the resistor 5, and when this temperature reaches several hundred degrees, the explosive 6
suddenly explodes, cutting the cylindrical case 2 at the part that is mechanically weakened by the groove 1. As a result, the electrical connection between the upper terminal 7 and the lower terminal 8 is broken, and the lightning arrester b is completely separated from the power distribution line L, thereby preventing a grounding accident of the power distribution line.

However, since the conventional disconnection device a performs the disconnection operation by detonating the explosive 6 contained therein, it generates a loud sound during operation and becomes a source of noise. Therefore, if there are residential buildings nearby, there are restrictions on installation.

Furthermore, since the explosive 6 is incorporated, the material cost is high, and the assembly has to be carried out in a special factory capable of handling hazardous materials, so there is a drawback that the manufacturing cost is high. Furthermore, if the explosive 6 absorbs moisture, it loses its blasting ability, so in this respect it was necessary to be careful in handling it.

C. Purpose of the Invention The present invention aims to prevent noise generation and reduce manufacturing costs by providing a structure of a disconnection device that does not use explosives.

D. Structure of the Invention The present invention includes disposing an upper electrode and a lower electrode through a gap in an outer cylindrical case made of an insulating material, and connecting an annular resistor between the upper electrode and the lower electrode in parallel with the gap. an upper terminal and a lower terminal electrically connected to the upper electrode and the lower electrode, respectively, are provided at both ends of the outer cylindrical case; A stopper having an opening larger than the outer diameter of the flange and smaller than the outer diameter of the lower end of the lower electrode is formed protrudingly on the inner circumferential surface of the outer cylinder case, and the flange of the lower terminal is connected to the flange of the lower terminal through an annular body made of thermoplastic resin. The lower terminal has a configuration in which an elastic member applies a biasing force to the lower terminal to be engaged with the opening of the stopper, and to pull the lower terminal out of the outer cylindrical case when the thermoplastic resin ring is melted.

E. Embodiment In FIG. 3 showing an embodiment of the present invention, 9 is a bell-shaped outer case made of an insulating material, and 9a is provided to make the shoulder part of the outer case 9 weaker than other parts. An annular groove, 10 is an upper electrode, 11 is a lower electrode, G is a gap formed by the upper electrode 10 and the lower electrode 11, 12 is an annular resistor sandwiched between the upper electrode 10 and the lower electrode 11, 13 14 is an upper terminal made of a round flat screw fastened with a nut into a hole in the neck of the outer cylinder case 9, and 14 is an upper terminal 13.
15 is a first clamping coil spring interposed between the upper electrode 10 and the first washer 14; 16;
17 is a resin lower terminal holder screwed onto the lower inner peripheral surface of the outer cylindrical case 9, and 18 is a lower terminal holder. 17, the lower terminal 16
A protruding annular stopper 19 has an opening 18a larger than the outer diameter of the flange 16a on the periphery of the head of the lower terminal 16.
A ring body 20 is made of thermoplastic resin and is sandwiched between the stopper 18 and has an airtight sealing function and a disconnection function as will be described later. 22 is the stopper 18 and the second washer 2.
A second compression coil spring (elastic member) 23 installed between the outer cylindrical case 9 and the lower terminal holder 17 is a sealing resin that fills the joint surface between the outer cylindrical case 9 and the lower terminal holder 17 to improve airtightness. The resistance value of the resistor 12 determines the current sensitivity of the disconnection operation, and is set to an appropriate value. In order to operate at high speed, this resistance value is set to, for example, several kilohms to ten-odd kilohms.

The disconnection device A having the above configuration is connected between the power distribution line L and the ground E in a state in which it is connected in series to the lightning arrester b as shown in FIG. 2, and operates as follows.

When lightning arrester b is normal, when an abnormal surge occurs in distribution line L due to lightning or the like, lightning arrester b becomes in a state of discharging it to the ground, and gap G of disconnection device A becomes in a flash fault state. As a result, when the abnormal surge is discharged to the ground E, the lightning arrester b blocks the follow-on current and returns to the normal state.
In addition, during this abnormal surge absorption operation, the path of the current flowing through the disconnection device A is from the upper terminal 13 to
First washer 14 → first compression coil spring 1
5 → Upper electrode 10 → Gap G → Lower electrode 11 →
This is the order of the lower terminal 16.

On the other hand, when lightning arrester b is damaged or its characteristics have deteriorated due to aging and it is no longer able to maintain the ground voltage of distribution line L, disconnection device A performs the following operation to disconnect lightning arrester b from distribution line L. Or separate it from the earth E.

When the characteristics of lightning arrester b deteriorate and the ability to maintain the ground voltage is lost, a leakage current flows from lightning arrester b to earth E through disconnection device A in the following order. That is, upper terminal 13 → first washer 14 → first compression coil spring 15 → resistor 12 → lower electrode 11 →
This is the order of the lower terminal 16. This leakage current causes the resistor 12 to generate heat, raising the temperature inside the disconnection device A. When this temperature reaches a certain level,
The ring body 19 made of thermoplastic resin is softened and sheared by the biasing force of the second compression coil spring 22, which is an elastic member. Then, as shown in FIG. 4, the lower terminal 16 is released from the stopper 18 of the lower terminal holding fitting 17, separates from the lower electrode 11, and pulls out from the outer case 9. Note that when the thermoplastic resin ring body 19 is sheared, the first compression coil spring 15 moves the upper electrode 10, the lower electrode 11, and the resistor 12 downward while maintaining their positional relationship, and It serves to press the lower edge of the electrode 11 against the stopper 18 and maintain electrical connection between them and the upper terminal 13. As a result of the lower terminal 16 being removed from the outer case 9, the lightning arrester b is connected to the distribution line L or the ground E.
be completely separated from.

The disconnection operation shown in FIG. 4 is performed when the leakage current is relatively small. On the other hand, when the degree of deterioration of the lightning arrester b is large and an excessive lightning surge hits the distribution line, the gap G will be discharged. In such a case, it is necessary to perform the disconnection operation more quickly. When a large current flows through the gap G, the internal pressure of the disconnection device A rapidly increases, and the weak portion 9' formed by the annular groove 9a in the shoulder of the outer case 9 is shown in FIG. Break as shown. This makes it possible to perform a rapid disconnection operation against lightning surges that exceed the performance of the arrester.

Next, other embodiments of the present invention will be described. This further promotes the rapid disconnection operation as explained in FIG. This structure is similar to the upper electrode 10 in the configuration of the first embodiment shown in FIG.
has a configuration as shown in FIG. That is, in the upper electrode 10 shown in FIG. 6, an explosive agent 24 other than gunpowder is embedded in a hole drilled in the center, and the hole is sealed with a resin material 25 or the like. The explosive agent 24 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, its handling is relatively safe.

The operation of this other embodiment is basically the same as that of the first embodiment. However, if the current is large and the temperature inside the disconnection device A' rises rapidly,
Before the ring body 19 made of thermoplastic resin is sheared, the explosive agent 24 expands and increases the internal pressure, so that a breaking operation as shown in FIG. 5 is performed. This breaking operation is performed much more rapidly and reliably than in the first embodiment.

The separating devices A and A' of each of the above embodiments are the fourth
If the power distribution line L is divided into two parts by the disconnection operation shown in FIG.
The user then knows that the characteristics of lightning arrester b have deteriorated, and can take appropriate measures such as replacing it.

F. Effects of the Invention The present invention does not use explosives and performs the separation operation by fusing the thermoplastic resin, so no explosion noise is generated during operation. Therefore, there is no need to consider noise countermeasures, and the degree of freedom in installation increases, resulting in a wider range of use.

Furthermore, the thermoplastic resin used in the present invention is considerably cheaper than explosives, and does not require special assembly equipment unlike when explosives are used, so the manufacturing cost can be reduced. Can be done.

Further, in the present invention, the hermetic sealing function and the disconnection function within the disconnection device are performed by a ring made of thermoplastic resin. Since the ring body is a ring body, the ring body of the present invention can be obtained with the minimum necessary volume of material, and the operating characteristics can be adjusted by the volume used, making it easy to set the operating characteristics. Furthermore, since the opening diameter of the stopper is made larger than the outer diameter of the flange of the lower terminal and smaller than the outer diameter of the lower end of the lower electrode, when the ring body melts, the flange of the lower terminal is pushed against the stopper by the urging force of the elastic member. Pass through the opening
At the same time as falling off from the lower terminal holding part, the upper electrode,
The lower electrode and the resistor are moved downward by the biasing force of the first compression coil spring while maintaining their positional relationship, and the lower edge of the lower electrode is pressed against the stopper. Therefore, the parts of the device of the present invention do not separate due to the melting of the ring.
Subsequent repairs will be easier. Furthermore, since the lower terminal falls off and separates from the lower terminal holder, the accident state can be easily confirmed from the outside, making maintenance and inspection easier.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional disconnection device, FIG. 2 is a circuit diagram showing the disconnection device connected with a lightning arrester between a distribution line and the ground, and FIG. 3 is a half-sectional view showing an embodiment of the present invention. , FIGS. 4 and 5 are partial sectional views and front views illustrating two types of separating operations, and FIG. 6 is a half sectional view showing another embodiment of the present invention. 9... Outer cylinder case, 10... Upper electrode, 11...
... lower electrode, 12 ... resistor, 13 ... upper terminal, 16 ... lower terminal, 16a ... flange, 1
8... Stopper, 19... Thermoplastic resin, 22
...elastic member (second compression coil spring),
A, A'...Separation device, G...Gap.

Claims (1)

[Claims] 1. An upper electrode and a lower electrode are disposed through a gap in an outer cylinder case made of an insulating material, and a ring-shaped resistor is housed between the upper electrode and the lower electrode in parallel with the gap, and the outer cylinder case is made of an insulating material. In a case in which an upper terminal and a lower terminal are provided at both ends of the case and are electrically connected to the upper electrode and the lower electrode, respectively, a flange is formed at the upper end of the lower terminal, and the outer diameter of the flange is larger than the outer diameter of the flange. , and a stopper having an opening smaller than the outer diameter of the lower end of the lower electrode is formed protrudingly on the inner peripheral surface of the outer cylinder case,
The flange of the lower terminal is locked to the opening of the stopper via a ring made of thermoplastic resin, and when the ring made of thermoplastic resin melts, the lower terminal is removed from the outer case. What is claimed is: 1. A grounding wire disconnection device characterized in that an elastic member applies a biasing force to cause