JPH0320978Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention is a lightning wire breakage protection device for preventing the vicinity of a portion of an insulated wire supported by an insulator from melting down due to follow-on current after a lightning strike. It is related to.

2. Description of the Related Art A support device as shown in FIG. 6 has already been proposed as a support device capable of preventing a portion of an insulated wire supported by an insulator from melting down due to a lightning strike. (Utility Model Publication No. 59-152630). This support device A supports an insulated wire 5 on the head 3a of an insulator body 3 attached to a cross arm 1 with an insulated bind wire 6 whose surface is made of an insulating material at least, and a voltage is applied to the cross arm 1. A current limiting element unit 2 equipped with a current limiting element made of a material with non-linear current characteristics is attached with its ground side electrode 2b, and the insulated covered electric wire 5 is attached to the discharge side electrode 2a of the current limiting element unit 2. An arcing horn 4 is supported opposite to each other with an air gap between them.

This support device A is damaged by the insulated electric wire 5 due to a lightning strike.
The surge generated in the arcing horn is extinguished by causing a discharge in the air gap between the insulated wire 5 and the arcing horn 4, and then passing it through the current limiting element unit 2 to the ground side. In other words, the current limiting element unit 2 has a non-linear resistance characteristic, so when high voltage is applied due to a surge, the resistance decreases and the voltage is released to the ground, returning to the normal line voltage after the surge disappears. However, as the resistance value increases, this is interrupted, the arc generated in the air gap is quickly extinguished, and the insulation is restored.

Further, as a device having the same function as the support device A, a support device B as shown in FIG. 7 is also being used.

In this support device B, the discharge position between the insulated wire 5 and the arcing horn 4 in the support device A is not constant, and as shown in FIG. In consideration of the possibility that the current limiting element unit 2 may not function, the discharge fitting 7 is attached to the insulated wire 5 with the discharge fitting 7 facing the arcing horn 4. The discharge fitting 7 is in the form of a bolt, and is screwed onto a bracket 8 made of an insulating material which is gripped and attached to the insulated wire 5 having a needle-shaped tip. At this time, the tip needle part breaks the insulation coating and is pressed against the internal conductor, thereby electrically connecting the internal conductor. The bolt head 7a exposed to the outside serves as a discharge electrode. Since discharge occurs intensively in the arcing horn 4 from the bolt head 7a, discharge along the path shown in FIG. 6A is prevented.

For the purpose of keeping the discharge position constant as shown in the support device B shown in FIG.
The idea of attaching it to is also described in Japanese Utility Model Application Publication No. 58-5225. As shown in FIG. 8, the support device C of this publication includes an insulated wire 5 and an insulated cover 20.
Attach a wire clamp 21 covered with
1a is made to protrude toward the current limiting element unit 2.

Problems to be solved by the invention In the above-mentioned conventional support devices A, B, and C, if the characteristics of the current-limiting element deteriorate due to causes such as loss of airtightness of the current-limiting element unit 2, the current-limiting element Unit 2 loses its current cutoff function and after absorbing the surge,
It becomes impossible to block the follow-on current due to the normal ground voltage of the insulated wire. Before the ground fault is detected at the substation or the like and the system is disconnected, the insulated wire 5 melts around the discharge start point due to this follow-on current and breaks, causing serious damage to the distribution system. There was a problem that caused significant damage.

Note that the support device C shown in FIG.
1a is larger than that of support device B shown in FIG. They are the same in that they melt and vaporize over time, causing the insulated wire 5 to break. In particular, since the discharge fitting 21a extends directly along the insulated wire 5, the discharge fitting 21a
There is also the problem that the arc heat of a directly acts on the insulated wire 5, accelerating wire breakage. In short, the improved conventional support devices B, C have a current limiting element unit 2
The design did not take into account the case where the discharge current cutoff function was lost, but only to keep the discharge position constant.

Means for Solving the Problems The present invention is an improvement on the conventional problems mentioned above. A current limiting element unit equipped with a current limiting element made of a material with non-linear current-voltage characteristics is attached to the above-mentioned cross arm by its ground side electrode, and the arcing horn is directed toward the insulated wire. In the device attached to the discharge side electrode of this unit, a T-shaped metal block with a metal lump integrally formed on the side of a cylindrical metal holding body is connected to the internal conductor of the insulated wire and the electric wire. It is attached to the insulated wire by being held by the holding body so that the tip of the metal lump faces the arcing horn with a predetermined gap, and this holding body The length extending on both sides shall be enough to protect the insulated wire from the arc heat generated in the metal lump, and the volume of the metal lump that will be melted and vaporized by the subsequent flow after absorbing the surge is determined by the diameter of the insulated wire. A lightning disconnection protection device for insulated wires, characterized in that the diameter of the internal conductor is several times larger than the diameter of the internal conductor, so that it is large enough to secure time until the system is disconnected at a substation, etc. be.

Effect In the above configuration means, even if the characteristics of the current limiting element unit deteriorate and the following current cannot be cut off, the following current will not be interrupted during the predetermined time until the substation, etc. detects a ground fault and disconnects the system. Thermal energy generated by the arc is absorbed by gradual melting and vaporization from the tip of a protruding metal lump with a sufficiently large volume on the side of the metal block, and the insulated wire is heated. You can avoid melting accidents. In particular, the diameter of the metal lump protruding from the holding body is set several times the diameter of the internal conductor of the insulated wire, making its volume sufficiently large, so the system can be disconnected by melting and vaporizing this part. Furthermore, since the holding body covers the insulated wire near the base of the metal lump, the insulated wire is protected from the heat of the arc generated in the metal lump.

Example The present invention will be described below with reference to Examples.

In FIG. 1, reference numeral 10 denotes an insulator, which is attached by arms 11 to arms of a wire support such as a steel tower (not shown). Reference numeral 12 denotes an insulated wire, which is held by the head 10a of the insulator by an insulated binding wire 13 whose at least the surface is made of an insulating material. Reference numeral 14 denotes a metal block, which is fixed by sandwiching the insulated wire 12 near the insulator 10 together with the insulated bind wire 13. Reference numeral 15 denotes a current limiting element unit including a current limiting element made of a material with nonlinear voltage-current characteristics, and is attached to the arm 11 with its ground end electrode 15a. 16
is an arcing horn, which is fixed to the discharge side electrode 15b of the current limiting element unit 15 so that its tip 16' faces the metal block 14.

Here, the metal block 14 is shown in FIGS. 2 and 3.
As shown in the figure, a metal lump 14d as a welding margin is integrally formed on one 14c of a pair of cylindrical metal holders 14a and 14c that open and close around a fulcrum pin 14, and when installed. When , it forms a T-shape.

The diameter of the metal lump 14d protruding to the side of the holding bodies 14b, 14c is several times (more than twice in the illustrated example) the diameter of the internal conductor 12a of the insulated wire 12, so that only this portion can be melted and vaporized. By doing so, we have obtained enough volume to secure the necessary time before disconnecting the system. The installation is performed using the insulated electric wire 12.
together with the insulated binding wire 13 and the holding body 14b, 1
4c on the inner R surface, both holding bodies 14b,
14c with the two bolts 17, 17 so that their palms meet, and further screw the connecting fittings 18, 18 into the screw holes 19, 19 of the holder 14c, the inner conductor 12a of the insulated wire 12 and This is done through electrical connection. For example, as shown in FIG. 4, this connecting fitting 18 is formed by forming a threadless part at the tip of the bolt, drilling from the tip side, and making the outer periphery of the tip a tapered surface so that the bolt is oriented toward the center. It has a circular blade. When the connecting fittings 18, 18 are screwed into the screw holes 19, 19, the blade 18a at the tip breaks through the insulation coating 12b and hits the internal conductor 12a, curling inward and creating a large contact area. electrically connected. Although the material of the metal block 14 is not particularly limited, it is preferable to use the same type of metal, for example, if the internal conductor 12a is a copper wire, the material of the metal block 14 is a copper alloy or the like so that electrical contact is less likely to occur. . The material of the connection fitting 18 is preferably the same as or softer than that of the internal conductor 12a. This is to prevent damage to the internal conductor 12a when screwed together. Note that this metal block 14 has a volume of a certain amount or more, and the insulated electric wire near the base of the metal block is
The connecting fitting 12 may be of any other structure as long as it can be attached by being covered with a cylindrical metal holding body. For example, it is possible to use a bolt with a needle-shaped tip, or it is also possible to use a bolt with a normal shape by stripping off the insulation coating 12b of the connecting portion in advance.

Further, the discharge electrode 16 has a flat conductor 16a as shown in FIG. screw 16
It is configured to be fixed at d. That is, this protrusion 16
b is adjusted by a connecting portion using a screw 16d provided in the middle so that it faces the metal lump 14d of the metal block 14. The reason why the protrusion 16b is circular is to prevent the discharge characteristics from varying depending on the polarity and to ensure stable discharge.
If the protrusion is linear, for example, the discharge voltage changes depending on the polarity of the discharge. This discharge electrode 16 is the discharge side electrode 15b of the current limiting element unit 15.
Any material that can be fixed to the metal block 14 and form a predetermined air gap between the metal block 14 and the metal block 14 may be used.

In the above configuration, when the current-limiting element unit 15 deteriorates and becomes unable to cut off the follow-on current due to the normal ground voltage after a lightning surge, the substation etc. detects a ground fault and disconnects the system. By melting and vaporizing the metal lump 14d of the metal block 14, the thermal energy caused by the following current is absorbed, and the holders 14b and 14c protect the insulated wire 12 from the heat generated at this time. Therefore, an accident in which the insulated wire 12 melts can be prevented, and even if a ground fault occurs, the insulated wire 12 is reliably protected, so that maintenance management of the system can be easily performed.

Effects of the invention According to the invention, in a device that combines an air gap and a current limiting element unit to prevent melting of the vicinity of an insulated wire supported by an insulator due to a lightning strike, The flow element unit has deteriorated,
Even if it becomes impossible to block the follow-on current, it is possible to prevent the insulated wire from melting due to the discharge energy absorption effect of the metal lump of the metal block and the heat shielding effect of the holding body.

[Brief explanation of the drawing]

Figure 1 is a front view showing one embodiment of the present invention;
3 are an enlarged front view and an enlarged side view of the metal block used in the embodiment of FIG. 1. Fig. 4 is a sectional view showing how the connecting fitting used in the metal block is connected to the internal conductor of the insulated wire, and Fig. 5 is an enlarged plan view showing the flat conductor constituting the discharge electrode. . Figures 6 to 8 show three examples (A) and (B) of conventional support devices, respectively.
It is a front view showing (C). 10... Insulator, 11... Bracelet, 12... Insulated wire, 14... Metal block, 15... Current limiting element unit.

Claims (1)

[Scope of Claim for Utility Model Registration] A current-limiting element unit that supports an insulated wire on the head of an insulator attached to an arm arm and is equipped with a current-limiting element made of a material with nonlinear current-voltage characteristics. The unit is attached to the above-mentioned arm via the ground side electrode, and the arcing horn is directed toward the insulated wire, and the metal lump is attached to the side of the cylindrical metal holding body. A metal block having an integrally formed T-shape is electrically connected to the internal conductor of the insulated wire, and the holding body is arranged so that the tip of the metal block faces the arcing horn with a predetermined gap therebetween. The holding body is attached to the insulated wire by holding it, and the length that this holding body extends on both sides of the base of the metal lump is such that it can protect the insulated wire from the arc heat generated in the metal lump, and the length of the holding body should be such that it can protect the insulated wire from the arc heat generated in the metal lump, and By making the volume of the metal lump that melts and vaporizes due to the following current several times the diameter of the internal conductor of the insulated wire, it is sufficient to secure enough time until the system is disconnected at a substation, etc. 1. A lightning disconnection protection device for an insulated wire, characterized in that the device is configured to have a size that is large enough.