JPH0216555B2 - - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention relates to a lightning arrester connected between a power distribution line and the ground. Sometimes, it relates to lightning arresters that have a built-in function to disconnect themselves.

B. Prior Art A lightning arrester a that is connected between a power distribution line L and the ground E and absorbs abnormal surges occurring in the power distribution line is generally used in combination with a lightning arrester disconnection device b as shown in FIG. In FIG. 1, the solid line indicates the case where the disconnection device b is connected to the earth E side, and the broken line indicates the case where the disconnection device b is connected to the distribution line L side. The reason why the above-mentioned disconnection device b is used in combination is that when the characteristics of lightning arrester a deteriorate due to damage or aging, and the insulation state can no longer be maintained against the normal ground voltage of the distribution line, the arrester can be automatically disconnected from the distribution line. This is to prevent grounding accidents caused by lightning arrester a.

Here, a conventional example of the above-mentioned separating device will be explained with reference to FIG.

This is the Japanese Patent Publication No. 49-1987, which the applicant had previously applied for.
This is described in Japanese Patent No. 42298, in which a gap g consisting of an upper electrode 3 and a lower electrode 4, and both ends of the gap g are placed in a cylindrical case 2 made of an insulator and having a groove 1 formed in a part of the inner circumferential wall. A resistor 5 tangential to the resistor 5 and an explosive 6 heated by the resistor 5 are housed, and openings at both ends thereof are connected to upper terminals 7 and 7 electrically connected to the upper electrode 3 and the lower electrode 4, respectively. It has a closed structure with a lower terminal 8.

This disconnection device b operates as follows in the connected state shown in FIG.

If the lightning arrester a is normal, when an abnormal surge occurs on the distribution line L due to a lightning strike or the like, the lightning arrester a will operate and discharge will occur in the gap g to absorb the surge voltage. As a result, the power distribution line L returns to normal voltage.

On the other hand, if the performance of lightning arrester a deteriorates due to aging or some other cause, even if no abnormal surge occurs, the leakage current will be caused by the normal ground voltage applied between distribution line L and ground E. flows to E. This current generates Joule heat in the resistor 5 and gradually increases the temperature inside the cylindrical case 2. When the temperature reaches several hundred degrees, the explosive 6 suddenly explodes, cutting the cylindrical case 2 at the mechanically weakened portion of the groove 1. As a result, the upper terminal 7
The electrical connection between the terminal 8 and the lower terminal 8 is cut off, and the lightning arrester a is completely separated from the distribution line L, thereby preventing a grounding accident on the distribution line L.

However, the above conventional device had the following problems.

(Problem 1) Since the disconnection device b is manufactured as a single device independent of the lightning arrester a and is treated as a separate product, it is necessary to set a price accordingly. Therefore, when the disconnection device b is used in combination with the lightning arrester a, there is a cost disadvantage.
In addition, workability is poor because each item is shipped separately and then assembled into one at the installation site.

(Problem 2) Since the disconnection device b performs its 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 must be carried out at a special factory capable of handling hazardous materials, resulting in a high manufacturing cost. 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 reduce the price and facilitate the installation work at the installation site by providing a lightning arrester incorporating the function of the above-mentioned disconnection device, and furthermore, the above-mentioned disconnection can be performed without using explosives. The purpose is to solve noise problems in this way.

D. Structure of the Invention The present invention divides the inside of an outer cylinder case 9 made of an insulating material into an upper chamber and a lower chamber by a partition 11 having a through hole 10, and in the upper chamber of the outer cylinder case 9, at least Characteristic elements 12 of nonlinear resistors, etc.
is assembled together with the first compression coil spring 18, and one end of the characteristic element 12 is connected to the line side terminal 20 by the first compression coil spring 18, and the lower end of the characteristic element 12 is electrically connected. The intermediate terminal 13 connected to the upper electrode 24 and the lower part are arranged to protrude into the lower chamber through the through hole 10 of the partition 11 to form a lightning arrester part, and the upper electrode 24 and the lower The electrode 25, the annular resistor 26 connected in parallel with the gap G between the upper electrode 24 and the lower electrode 25, and the flange 28a at the upper end connected to the lower electrode 25.
an external terminal 28 connected to the upper electrode 24,
A stopper 3 in which an assembly of a lower electrode 25, an annular resistor 26, and an external terminal 28 is formed on the lower inner peripheral surface of the lower chamber via a thermoplastic resin ring 31.
0, the upper electrode 24 and the intermediate terminal 1
A second compression coil spring 27 is interposed between the three buttocks, and an external terminal 28 protrudes from the lower chamber.
is applied an outward biasing force by the third compression coil spring 34 to open the opening 30 of the stopper 30.
The diameter of the hole a is made larger than the outer diameter of the flange 28a of the external terminal 28 and smaller than the outer diameter of the lower electrode 25 to form a separating functional portion.

Example An embodiment of the invention will be described with reference to FIG.

Reference numeral 9 denotes an outer cylindrical case made of an insulating material, and uses, for example, a hollow lightning arrester insulator tube with an extended lower part. The inside of this outer cylindrical case 9 is divided into an upper chamber and a lower chamber by a partition 11 having a through hole 10 at about a quarter of the lower side. The inner peripheral surface is formed into a female thread shape.
Insulating pleats 9a are formed on the outer circumferential surface of the upper chamber of this outer cylindrical case 9. 12 is a characteristic element of the lightning arrester housed in the upper space of the outer cylindrical case 9, and is, for example, a nonlinear resistor with excellent nonlinearity mainly composed of zinc oxide or the like, or a gap in this nonlinear resistor. connected in series is used. Reference numeral 13 denotes an intermediate terminal having a male screw 13b protruding from the center of a metal disc 13a. It is fastened and fixed. 15 is an annular seal member 16 and 17 sandwiched in a compressed state between the intermediate terminal 13 and the partition 11;
is an annular buffer member and a metal washer sandwiched between the partition 11 and the first nut 14. Reference numeral 18 denotes a first compression spring that presses the characteristic element 12 of the lightning arrester against the intermediate terminal 13 and establishes an electrical connection. It is pressed into the outer cylindrical case 9. 20 is a track side terminal fixed to the metal seal member 19, 21 is a track side insulating cover screwed to a wing-shaped mounting bracket 22 fixed to the metal seal member 19, and 23 is a column on which the outer cylinder case 9 is mounted. This is a support band for fixing to etc.
24 is an upper electrode, 25 is a lower electrode, and by sandwiching an annular resistor 26 between them, a gap G of a constant length is formed. The resistance value of the resistor 26 determines the current sensitivity of the disconnection operation, and is set to an appropriate value. For high-speed operation, this resistance value is set to, for example, several kilohms to ten-odd kilohms. 27 is a second compression spring for electrically connecting the upper electrode 24 and the intermediate terminal 13. 28 is an external terminal made of a countersunk screw whose head is in contact with the lower electrode 25; 29 is a resin external terminal holder screwed onto the inner peripheral surface of the lower part of the outer cylindrical case 9;
30 is an annular stopper formed protruding from the inner circumferential surface of the external terminal holder 29, having an opening 30a larger than the outer diameter of the flange 28a around the head of the external terminal 28; 31, the external terminal 28; A thermoplastic resin ring 32 is sandwiched between the flange 28a and the stopper 30 and has an airtight sealing action and a separating action as will be described later, and a ring member 32 fastens the external terminal 28 to the external terminal holder 29 via a washer 33. Second to do
The nut 34 is a third compression coil spring 35, 36 that is installed between the stopper 30 and the washer 33 and provides a biasing force for the separation operation.
37 is a washer that holds a connection line (not shown) to the ground side, and 37 is a third nut that tightens the washers 35 and 36 with the second nut 32.

The lightning arrester A having the above structure has its line side terminal 20 connected to the distribution line L, its external terminal 28 connected to the ground E, and operates as follows.

When the lightning arrester part above the partition 11 of the device of the present invention is normal, when an abnormal surge occurs in the distribution line L due to a lightning strike, the resistance value of the characteristic element 12 of the lightning arrester such as a non-linear resistor decreases and discharges it to the ground. At the same time, the gap G in the disconnection function section below the partition 11 becomes in a flashing state. As a result, when the abnormal surge is discharged to the ground E, the characteristic element 12 of the lightning arrester such as a non-linear resistor blocks the following current and returns to the normal state. In addition, during this abnormal surge absorption operation, the path of the current flowing from the distribution line L toward the earth E is as follows: line side terminal 20 → metal seal member 19 → first compression coil spring 18 → nonlinear resistor, etc. The order of characteristics of the lightning arrester is 12 → intermediate terminal 13 → second compression coil spring 27 → upper electrode 24 → gap G → lower electrode 25 → external terminal 28.

On the other hand, when the characteristic element 12 of the lightning arrester, such as a non-linear resistor, deteriorates and loses its ability to maintain insulation against the ground voltage of the distribution line, leakage current flows from this characteristic element 12 toward the earth E in the following order: pass. That is, the order is the characteristic element 12 → intermediate terminal 13 → second compression coil spring 27 → upper electrode 24 → annular resistor 26 → lower electrode 25 → external terminal 28. This leakage current causes the resistor 26 to generate heat,
The temperature of the lower part of the outer cylinder case 9 is increased.
When this temperature exceeds a certain level, the thermoplastic resin 31 softens and the third compression coil spring 34
is sheared by the urging force of As shown in FIG. 4, the external terminal 28 is held by an external terminal holding member 29
It is released from the lock by the stopper 30, moves away from the lower electrode 25, and pulls out from the outer cylinder case 9. Note that when shearing the thermoplastic resin 31, the second compression coil spring 27 moves the upper electrode 24, the lower electrode 25, and the resistor 26 downward while maintaining the positional relationship of the lower electrode 25. It functions to press the outer periphery of the lower end surface against the stopper 30 and maintain electrical connection between them and the intermediate terminal 13. As a result of the external terminal 28 being removed from the outer case 9 in this manner, the lightning arrester A is completely disconnected from the earth E, and a ground fault is prevented.

If the external terminal 28 is disconnected in this way,
When inspecting and inspecting the power distribution line L for maintenance, this can be easily discovered. Then, it is known that the characteristic element 12 of the lightning arrester A has deteriorated, and appropriate measures such as replacement work can be taken.

F. Effects of the Invention The present invention has a built-in function in the lightning arrester itself that automatically disconnects the lightning arrester from the installation location when the characteristics of the lightning arrester deteriorate and the normal ground voltage of the distribution line cannot be maintained. There is no need to assemble a separate disconnection device to the lightning arrester as in the past. Therefore, work efficiency at the installation site is improved, and less installation space is required. In particular, the outer cylindrical case of the lightning arrester can be separated and used as an insulating jacket for the functional part, and what used to be two pieces can be assembled into one device in the same process, reducing manufacturing costs. Furthermore, in the lightning arrester of the present invention, when the disconnection function is activated and the external terminal falls out as shown in Figure 4, the live part is almost completely covered by the outer case with excellent insulation properties. The system is more secure than the conventional system shown in FIG. 2, for example. Furthermore, the detached equipment can be easily restored by replenishing a few parts. Furthermore, the present invention does not use explosives and performs the disconnection 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.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing the conventional state in which a disconnection device is connected with a lightning arrester between the distribution line and the ground.
3 is a half sectional view showing an embodiment of the present invention, and FIG. 4 is a partial sectional view illustrating its cutting operation. 9... Outer cylinder case, 12... Characteristic element, 24...
... Upper electrode, 25 ... Lower electrode, 26 ... Resistor, 28 ... External terminal, 30 ... Stopper, 3
1...Thermoplastic resin, G...Gap, A...Surge arrester.

Claims (1)

[Scope of Claims] 1. The interior of an outer case made of an insulating material is divided into an upper chamber and a lower chamber by a partition having a through hole, and at least a non-linear resistance is provided in the upper chamber of the outer case. A characteristic element such as a body is assembled together with a first compression coil spring, and one end of the characteristic element is connected to a line side terminal by the first compression coil spring, and an electrical connection is made to the lower end of the characteristic element. An intermediate terminal connected to the casing protrudes into the lower chamber through a through hole of the partition to constitute a lightning arrester part, and an upper electrode and a lower electrode are arranged facing each other through a gap in the lower chamber of the outer cylindrical case, and the upper electrode and a ring-shaped resistor connected and arranged in parallel with the gap between the upper electrode and the lower electrode, an external terminal whose upper end flange is connected to the lower electrode, the upper electrode, the lower electrode,
The annular resistor and external terminal assembly is supported by a stopper formed on the lower inner circumferential surface of the lower chamber via a thermoplastic resin ring, and a second compression is applied between the upper electrode and the intermediate terminal. In addition to interposing a coil spring, a third compression coil spring applies an outward urging force to the external terminal protruding from the lower chamber, and the hole diameter of the opening of the stopper is made larger than the outer diameter of the flange of the external terminal. A lightning arrester characterized in that the separation function part is made smaller than the outer diameter of the lower electrode.