CN2824393Y - Induction thunder screening wire for preventing 10KV overhead insulative conductor from breaking by lightning striking - Google Patents

Abstract

An induction lightning shielding wire for preventing lightning breakage of overhead insulated conductors is a device for preventing lightning breakage of insulated conductors. The induction lightning drainage wire for lightning protection is installed in the middle of the three-phase insulated conductor of the overhead insulated line. The drainage wire is connected to the cross arm of the pole of the overhead line. The distance between phase insulated conductors is greater than 0.3 meters. The utility model has the advantages of simple structure, economy and practicality, simple and convenient implementation, low cost and small daily operation and maintenance workload. The induction lightning shielding wire has a good effect on reducing the lightning-induced overvoltage on the overhead insulated wire, and is suitable for preventing lightning strike and disconnection of the medium-voltage overhead insulated wire.

Description

Inductive lightning shielding wire for 10KV overhead insulated wires for lightning protection and disconnection protection

technical field

The utility model relates to a 10KV overhead insulated wire for preventing wire breakage caused by induced lightning overvoltage, which is a lightning protection device.

Background technique

The 10KV overhead insulated lines have a single circuit in a triangular arrangement and a double circuit in a vertical arrangement. There are two kinds of lightning overvoltages generated on overhead insulated lines, one is the direct lightning overvoltage caused by lightning directly striking the line, and the other is the induced lightning overvoltage caused by electromagnetic induction near the lightning strike line. About 20% of the lightning strikes on 10KV distribution lines are direct lightning strikes, and more than 50% of them are direct lightning strikes with a current exceeding 20kA; about 80% are induced lightning strikes, and more than 95% of them have a discharge current of less than 1000A. The insulation level of overhead distribution lines is low, even if lightning protection lines are installed, they will counterattack, and the effect of preventing direct lightning strikes is not great. The distribution line is mainly to prevent disconnection caused by induced lightning overvoltage. The main cause of lightning disconnection of insulated lines is that the power frequency freewheeling current burns the wire after lightning flashover. Studies have shown that when an overhead insulated line flashover is caused by lightning overvoltage, the instantaneous arc current is very large but the time is very short, generally a few microseconds to a few milliseconds, so the lightning flashover will only form a needle on the insulating layer of the insulated wire. holes without causing disconnection. However, when a lightning overvoltage flashover occurs, especially between two or three phases (not necessarily on the same pole) to form a metallic short-circuit channel, the arc energy will increase sharply. Because the insulating layer of the overhead insulated wire prevents the arc from slipping on its surface, the high-temperature arc root is fixed at the breakdown point of the insulating layer, and the continuous current of the power frequency arc (several thousand amperes) is concentrated and fixed at the pinhole of the insulated wire insulation breakdown. Burn until the wire is blown before the circuit breaker operates.

At present, the main measures to prevent the disconnection of insulated wires caused by lightning strikes can be divided into the following categories:

1) Install lightning protection devices: install overhead ground wires and lightning arresters to limit lightning overvoltage and absorb lightning energy. This method is expensive to apply and will increase the workload of daily operation and maintenance.

2) Extend the flashover path: the purpose is to make the arc easy to extinguish by extending the flashover path. This method is difficult to implement in practice, and it is difficult to locate the parts that need reinforced insulation.

3) Partial stripping of insulated wires: adopt anti-fuse measures and new insulators and fittings, partially strip the wires, which is equivalent to bare wires, and the arc can slide on the stripped part. After lightning flashover, the power frequency arc root is transferred or fixed in a special Burning on the metal fittings, thereby protecting the wire from being burned and broken, rather than being fixed at a certain point and ablated. This method damages the insulated wire and affects the life of the insulated wire, and the piercing type fittings have high requirements on the quality of the insulated wire.

Utility model content

The purpose of the utility model is to provide an induction lightning shielding wire for 10KV overhead insulated wires which is easy to implement, low in cost and easy to maintain.

The utility model is realized through the following technical scheme, the induction lightning shielding wire for preventing lightning strike and disconnection of 10KV overhead insulated conductor, which is characterized in that the induction lightning shielding wire for preventing lightning strike and disconnection is laid near the overhead insulated conductor, and the shielding wire and the insulated conductor The distance is 0.20 meters to 1 meter, and the shielded wire is installed and connected to the cross arm of the pole of the overhead insulated wire. There are many forced groundings at both ends and in the middle of the shielded wire. The mandatory grounding at multiple places in the middle is to set mandatory grounding every 2 to 5 poles, and the grounding resistance is less than 30 ohms.

The utility model lays the induction lightning shielding wire near the 10KV overhead insulated wire, does not affect the wire insulation performance of the original overhead line, greatly reduces the lightning induced voltage, avoids or reduces the lightning strike disconnection, is economical and practical, simple and convenient to implement, and low in cost. The operation and maintenance workload is small. The steel strand used as shielding wire adopts GJ-35 steel strand to meet the flow of induced lightning current. The shielded wire is connected to the cross-arm on each pole, and is naturally grounded through the pole. Every 2 to 5 poles are forced to be grounded. The grounding resistance is less than 30 ohms, which meets the requirements for reducing the induced lightning voltage. The EMTP software is used to simulate the lightning induced overvoltage, the relationship between each parameter and the amplitude and waveform of the induced voltage is analyzed, and the lightning induced voltage of the overhead line with the induced lightning shielding line is verified by an example , the results show that through the electromagnetic coupling and shunting effect of the shielded wire, the lightning induced voltage on the insulated wire can be reduced, and the shielded wire has a good effect on reducing the lightning induced voltage on the overhead insulated wire. Inductive lightning shielding wire is used for 10KV overhead insulated wires to prevent lightning breakage, avoid damage to insulated wires, and prolong the service life of insulated wires.

Description of drawings

Fig. 1 is the structural representation of the single loop of the utility model;

Fig. 2 is the structural representation of the dual circuit of the present utility model;

In the figure: 1 insulated wire, 2 pole, 3 cross arm, 4 shielded wire.

Detailed ways

Example 1:

As shown in Figure 1, an induction lightning shielding wire 4 is set in the middle of the three-phase insulated wire 1 of the 10KV triangular overhead line of the single circuit. The distance between the shielding wire 4 and the insulated wire 1 is 0.20 meters to 1 meter. 4 Installed and connected to the cross arm 3 of the pole 2 of the overhead line, the two ends and the middle of the shielded wire are provided with mandatory grounding every 2 to 5 poles, and the grounding resistance is less than 30 ohms.

Example 2:

As shown in Figure 2, two lightning induction shielding wires 4 are laid between the two rows of insulated wires 1 of the 10KV vertically arranged overhead lines of the double circuit. 4 Installed and connected to the cross arm 3 of the pole 2 of the overhead line, the two ends and the middle of the shielded wire are provided with mandatory grounding every 2 to 5 poles, and the grounding resistance is less than 30 ohms.

Claims (2)

1. A 10KV overhead insulated conductor lightning protection shielding wire for lightning protection, which is characterized in that an induction lightning shielding wire for preventing lightning disconnection is provided near the overhead insulated conductor, and the distance between the shielding wire and the insulated conductor is 0.20 meters ~ 1 meter, the shielded wire is installed and connected to the cross arm of the pole of the overhead insulated wire, and the two ends and the middle of the shielded wire are provided with multiple forced grounding. 2. According to claim 1, the induction lightning shielding wire for 10KV overhead insulated wires to prevent lightning strikes and disconnection is characterized in that the mandatory grounding in the middle is that every 2 to 5 poles are provided with mandatory grounding, and the grounding resistance Less than 30 ohms.

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