CN101105991A - Puncture-type lightning protection fittings for preventing overhead insulated conductors from being disconnected by lightning - Google Patents

Abstract

The utility model relates to a puncture type lightning protection fitting for preventing overhead insulated wires from being disconnected by lightning in the field of power distribution network. The key point of the design of the fitting is that it is directly installed on the upper end of the insulator. There is a piercing electrode in the upper cap of the fitting, which directly penetrates the insulation layer of the insulated wire and is in close electrical contact with the conductor inside the insulated wire, leading the electricity directly to the insulated wire. The upper fitting top cap and the fitting chassis constitute the exposed upper metal electrode of the insulator. Under the action of lightning overvoltage, the piercing blade that is in close contact with the conductor will lead the lightning overvoltage to the metal electrode on the upper part of the insulator, so that the lightning overvoltage is directly added between the upper metal electrode and the lower metal electrode of the insulator, causing the surface of the insulator to strike. wear. In this way, the insulated wire is transformed into a similar bare wire structure, which makes it difficult to be burned by power frequency freewheeling, thereby protecting the overhead insulated wire from being disconnected during a lightning strike. The fitting is maintenance-free during operation, and is especially suitable for application on 10kV overhead insulated conductors.

Description

Puncture-type lightning protection fittings for preventing overhead insulated conductors from being disconnected by lightning

technical field

The invention relates to the field of electric power distribution network, which is used for overhead distribution lines of electric power system, and is mainly used for preventing lightning breakage of overhead insulated wires, and is especially suitable for use on 10kV overhead insulated wires.

technical background

In order to reduce the faults of overhead distribution lines caused by external factors such as trees, birds, and snow accumulation, and improve the reliability of power supply, overhead insulated wires have been widely used at home and abroad in recent decades. Insulated wires do solve the corridor and safety problems that bare wires cannot solve. Compared with cables, it has the advantages of low investment and fast construction, but its lightning disconnection problem is very prominent. It has become a problem in the distribution network system. important issues that urgently need to be addressed.

Economically developed countries have used overhead insulated wires for power transmission and distribution for a long time, accumulated a lot of operating experience, and adopted many preventive measures and methods, as follows.

Overhead lightning protection line: In open areas, erecting overhead lightning protection lines on the same pole to deal with the induced overvoltage of distribution overhead insulated lines is a traditional method with a large investment. However, due to the low insulation level of the distribution line design, it is very easy to cause flashover after lightning strikes the overhead lightning conductor, which will still cause power frequency freewheeling to fuse the insulated conductor. Therefore, this method is rarely used abroad.

Zinc oxide arrester: In recent years, zinc oxide arresters have been widely used in lines to limit lightning overvoltage by taking advantage of their non-linear resistance characteristics and fast blocking power frequency continuous current characteristics. Their protection range is limited, and basically they can only protect the pole equipment. . Japan, the United States, Canada and other countries have invested heavily in the transformation of the line. After installing three (phase) zinc oxide arresters on each base pole, the lightning disconnection rate has been reduced from the original 93.3% to 2.7%, basically no recurrence Lightning strike disconnection accident. However, with this method, a large number of lightning arresters will be used. When the quality of lightning arresters is poor, it may cause more line accidents during operation and affect safe operation.

Clamp insulators: Tokyo Electric Power Company in Japan uses discharge clamp insulators to prevent insulated wires from being disconnected by lightning. That is, peel off the insulation layer at the fixed place of the insulated wire, install a specially designed metal wire clip, and set the arc discharge gap. When lightning flashover triggers power frequency freewheeling, the power frequency freewheeling arcs on the metal clamp until the line trips to extinguish the power frequency freewheeling, thereby avoiding burning insulators and fusing insulated wires.

According to the same principle, the covered line power distribution system (SAX system) developed by Finland's Nokia company uses suspension clamps and other devices as flashover protectors, and the suspension clamps withstand power frequency arcs. But the anti-seismic performance of this device is relatively poor, and when the line is blown and danced by wind, it often breaks down.

Increasing the flashover path: By increasing the flashover path, reducing the power frequency arc establishment rate is another way to prevent lightning strike and disconnection accidents of overhead insulated lines. The Russian State Electric Power Company first proposed the long flashover gap protection method. Install a U-shaped insulation flashover path on the cross arm, so that the impulse discharge voltage between the U-shaped head and the insulated wire is lower than the insulator discharge voltage. When the lightning overvoltage occurs, the gap precedes the breakdown and flashover of the insulator, and develops along the insulation flashover path. The insulation path is designed to be long enough to prevent power frequency freewheeling from building an arc and cut off power frequency freewheeling. But this method is immature and has not been promoted and applied.

Improve line insulation level: replace porcelain insulators in power distribution lines with silicon rubber insulating crossarms, improve line insulation level across the line, and power frequency freewheeling caused by lightning cannot establish arcs due to large creepage distances.

In order to reduce the cost of the line, it is possible to use overhead insulated wires to strengthen local insulation, that is, to thicken the insulation where the insulated wires are fixed. This is also an attempted method, and the effect is not very satisfactory.

Line overvoltage protector: In some lightning-damaged countries such as Japan, Australia, the United States and Europe, a large number of line overvoltage protectors have been widely used on overhead insulated lines in recent years, which are actually out-of-band gap arresters. The device uses the outer gap to form an outer discharge gap to the zinc oxide current limiting element. When the line has a lightning overvoltage, the outer gap is first discharged, and the lightning current is released through the zinc oxide current limiting element, while the power frequency freewheeling current is absorbed by the zinc oxide The current limiting element is cut off, so as to prevent the occurrence of lightning breakage accidents of overhead insulated lines. After the protection device is put into operation, the maintenance and repair workload is relatively large.

To sum up, although the above-mentioned methods can effectively prevent wire breakage due to lightning strikes, there are still some problems as follows: some of the current anti-breakage fittings, some insulated wires need to be stripped for a long length before use, and the exposed parts are relatively large. Large, this will have a certain impact on the sealing and insulation of the wires, and will seriously affect the mechanical strength and service life of the wires; some installations are more complicated and not easy to use in practice. However, the use of surge arresters and overvoltage protectors has good protection effects, but there are mainly problems such as difficult operation and maintenance.

Contents of the invention

The purpose of the present invention is to provide the field with a puncture type lightning protection fitting for preventing overhead insulated wires from being disconnected by lightning, so that it can solve the unsolved technical problems of similar products. The present invention is achieved through the following technical solutions.

A puncture-type lightning protection fitting for preventing overhead insulated wires from being broken by lightning. Electrodes, overhead insulated wires, external hexagonal bolts, metal electrodes at the lower end of insulators, extension electrodes A, and extension electrodes B are mainly installed directly on the upper end of the insulator. There are electrodes with punctures in the upper cap of the fittings, which can directly penetrate The insulating layer of the insulated wire is in close electrical contact with the conductor inside the insulated wire, and the electricity is directly led to the top cap and the chassis of the upper fitting to form the exposed upper metal electrode of the insulator.

One design scheme is that metal electrodes with puncture structures are set in the metal fitting top cap; another design scheme is that metal electrodes with puncture structures are set in the metal fitting chassis; A metal electrode with a puncture structure is also provided in the chassis of the hardware.

The above-mentioned puncture type lightning protection fittings for preventing overhead insulated conductors from being disconnected by lightning strikes, the first option is that the chassis of the fittings is provided with electrodes extending to both sides. The second option is that the chassis of the fittings does not have electrodes extending to both sides

The above-mentioned puncture type lightning protection fittings for preventing overhead insulated conductors from being disconnected by lightning strikes, the first option is that the metal electrodes at the lower end of the insulator are provided with electrodes extending to both sides. The second option is that the metal electrodes at the lower end of the insulator are not provided with electrodes extending to both sides.

The puncture-type lightning protection fittings for preventing overhead insulated conductors from being disconnected by lightning strikes, the first option is that the chassis of the fittings is integrated with the insulator. The second option is that the hardware chassis and the insulator are not connected as a whole.

Under the action of lightning overvoltage, the piercing blade that is in close contact with the conductor will lead the lightning overvoltage to the metal electrode on the upper part of the insulator, so that the lightning overvoltage will be directly added between the upper metal electrode and the lower metal electrode of the insulator, resulting in shock on the surface of the insulator. wear. In this way, the insulated wire is changed into a similar bare wire structure, which makes it difficult to be burned out by power frequency freewheeling, thereby protecting the overhead insulated wire from being disconnected during a lightning strike. The fitting is maintenance-free during operation, and is especially suitable for application on 10kV overhead insulated conductors, suitable for copper and aluminum overhead insulated conductors.

Electrodes extending to both sides are added to the metal chassis, and electrodes extending to both sides are added to the metal electrodes at the lower end of the insulator, in order to protect the porcelain surface of the insulator from arc burning, and to avoid the insulator from being burned out in the event of a lightning strike. In this case, due to the action of load current or short-circuit current, the arc will be electrodynamically driven to the outside of the extension electrode. In this way, the arc burns in the air gap and does not burn on the surface of the insulator, thereby protecting the surface of the insulator from burning damage.

The lightning protection fitting adopts a torque nut to control the cutting depth of the piercing blade to ensure good electrical contact between the blade and the conductor without damaging the wire.

An insulating cover is installed on the outside of the lightning protection fitting to ensure insulation.

Its advantages are:

(1) Easy to install, no need to strip the insulation layer of the insulated wire, and there is no size requirement for up, down, left, and right during installation;

(2) It has the indication function of lightning short-circuit accident (the bottom of the outer insulating cover has obvious color change after lightning strike and arc burning, from black to white);

(3) Maintenance-free, outstanding burning resistance;

(4) The installation of fittings has nothing to do with the direction of load flow;

(5) The impact on the breakdown voltage of the line insulation is small;

(6) The device has excellent reusability;

(7) Protect the surface of the insulator from arc burn damage;

(8) Free from grounding.

The lightning protection fitting has the advantages of lightning protection against broken wires, no stripping of the wire insulation layer, simple construction, with an insulating cover, safe operation, high reliability, and maintenance-free during operation.

Description of drawings

Fig. 1 is a structural schematic diagram of the hardware chassis and the insulator not being connected as a whole;

Fig. 2 is a schematic side view of Fig. 1;

Fig. 3 is a structural schematic diagram of the chassis of the fittings and the top cap of the fittings;

Fig. 4 is the puncture schematic diagram between the electrode with puncture and overhead insulated wire;

Fig. 5 is a schematic diagram of the structure of the hardware chassis and the insulator not connected as a whole, and with extended electrodes.

Fig. 6 is a schematic diagram of the structure of the chassis of the hardware and the insulator as a whole, with extended electrodes.

The serial numbers and names of the above drawings: 1. Fitting chassis, 2. Fitting cap, 3. Half-ring ear clip, 4. Silicone rubber insulating sheath, 5. Torque nut, 6. Screw rod, 7. Insulator, 8. Electrode with puncture, 9, overhead insulated wire, 10, outer hexagon bolt, 11, metal electrode at the lower end of the insulator, 101, electrode A, 111, electrode B.

Detailed ways

Embodiment (1) of puncture-type lightning protection fittings in which the chassis of the fittings is not connected to the insulator: According to Fig. 1 to Fig. 5, the installation steps are as follows.

(1) Unscrew the two outer hexagonal bolts 10 on the fitting top cap 2, and remove the fitting top cap 2;

(2) Put the metal fitting chassis 1 into the neck of the insulator 7, so that the U-shaped groove of the metal fitting chassis 1 is completely matched with the U-shaped groove at the top of the insulator 7, and then put the overhead insulated wire 9 into the U-shaped groove of the hardware chassis 1;

(3) Insert the half-ring ear clip 3 into the neck of the insulator 7, snap both ends into the side grooves on both sides of the hardware chassis 1, pull the half-ring ear clip 3 upward with even force with both hands, and then tighten the half-ring ear The nuts at both ends of the clip 3;

(4) Install the hardware top cap 2, and tighten the two hexagon bolts 10 on the top cap;

(5) Use a special torque wrench to tighten the torque nut 5 until it is broken;

(6) Cover the silicone rubber insulating sheath 4 well.

Implementation mode (2) of puncture-type lightning protection fittings in which the fittings chassis and insulators are integrated: According to Figure 6, the installation steps are as follows.

(1) Put the wire into the U-shaped groove of the hardware chassis 1;

(2) Install the fitting top cap 2, and tighten the two outer hexagonal bolts 10 on the fitting top cap 2;

(3) Use a special torque wrench to tighten the torque nut 5 until it is broken;

(4) Cover the silicone rubber insulating sheath 4 well.

Claims (10)

1. A puncture-type lightning protection fitting for preventing overhead insulated wires from being disconnected by lightning, the lightning protection fitting comprising a fitting chassis (1), a fitting top cap (2), a half-ring ear clip (3), and a silicone rubber insulating sheath (4), torque nut (5), screw rod (6), insulator (7), electrode with puncture (8), overhead insulated wire (9), external hexagonal bolt (10), extended electrode at the lower end of the insulator (11), It is characterized in that it is directly installed on the upper end of the insulator (7), and there is an electrode (8) with a puncture in the top cap (2) of the upper part of the fitting, which directly penetrates the insulating layer of the insulated wire, and is connected with the inner part of the insulated wire (9). The conductor is in close electrical contact, and the electricity is directly led to the top cap (2) of the upper fittings and the chassis (1) of the fittings to form the exposed upper metal electrode of the insulator. 2. The puncture-type lightning protection fitting for preventing overhead insulated conductors from being disconnected by lightning according to claim 1, characterized in that a metal electrode (8) with a puncture structure is arranged in the top cap of the fitting. 3. The puncture-type lightning protection fitting for preventing overhead insulated conductors from being disconnected by lightning according to claim 2, characterized in that a metal electrode (8) with a puncture structure is provided in the chassis of the fitting. 4. The puncture-type lightning protection fitting for preventing overhead insulated conductors from being disconnected by lightning according to claim 2, characterized in that metal electrodes (8) with puncture structures are respectively provided in the top cap of the fitting and the chassis of the fitting. 5. The piercing lightning protection fitting for preventing overhead insulated conductors from being disconnected by lightning according to claim 1, characterized in that the fitting chassis (1) is provided with electrodes A (101) extending to both sides. 6. The puncture-type lightning protection fitting for preventing overhead insulated conductors from being disconnected by lightning according to claim 5, characterized in that the chassis (1) of the fitting is not provided with electrodes A (101) extending to both sides. 7. The puncture-type lightning protection fitting for preventing overhead insulated conductors from being disconnected by lightning according to claim 1, characterized in that the metal electrodes (11) at the lower end of the insulator are provided with electrodes B (111) extending to both sides. 8. The puncture-type lightning protection fitting for preventing overhead insulated conductors from being disconnected by lightning according to claim 7, characterized in that the metal electrodes (11) at the lower end of the insulator are not provided with electrodes B (111) extending to both sides. 9. The puncture type lightning protection fitting for preventing overhead insulated conductors from being disconnected by lightning according to claim 1, characterized in that the chassis of the fitting (1) and the insulator (7) are connected as a whole. 10. The puncture-type lightning protection fitting for preventing overhead insulated conductors from being disconnected by lightning according to claim 9, characterized in that the fitting chassis (1) and the insulator (7) are not connected as a whole.

Images