CN203747401U - Lightning protection device for distribution transformer - Google Patents

Abstract

A lightning protection device for distribution transformers. It includes a high-voltage arrester, a low-voltage arrester, an anti-backflow device, and first to third grounding bodies; one end of the high-voltage arrester is connected to the high-voltage side of the distribution transformer, and the other end is connected to the first grounding body; one end of the low-voltage arrester is connected to the low-voltage side of the distribution transformer The other end is connected to the third grounding body; one end of the anti-reflux device is connected to the neutral line of the distribution transformer and the shell, and the other end is connected to the second grounding body; the other ends of the first to third grounding bodies are simultaneously connected to the earth grounding grid connected. The effect of the utility model: the anti-backflow device can be used to force the lightning current to only discharge to the earth grounding grid, thereby preventing the lightning current introduced into the earth from the arrester from entering the distribution transformer again through the neutral line and damaging it. The first to third grounding bodies can be used to appropriately reduce the inverse conversion voltage generated by lightning strikes, so that the distribution transformer can be better protected against lightning.

Description

Lightning protection device for distribution transformer

technical field

The utility model belongs to the technical field of lightning protection devices for electrical distribution transformers, in particular to a lightning protection device for distribution transformers.

Background technique

With the development of the economy, the requirements for the reliability of the urban power distribution network are getting higher and higher, and the distribution transformer is an important equipment in the power distribution network. If the lightning protection measures for distribution transformers are not perfect, it may lead to frequent tripping of transformer protection caused by lightning strikes. The failure of transformers will not only have a great impact on the reliability of power grid operation, but also affect the people's production and living electricity and the industry image of the power system, and also directly affect the economic benefits of the power system.

Based on the normal operation and high reliability requirements of the distribution network, although the commonly used distribution transformers are equipped with lightning protection devices, a large number of distribution transformers are damaged due to lightning strikes every year. The reasons for the damage are various. Yes, here are a few main reasons:

1. The lightning protector on the high-voltage side of the distribution transformer cannot withstand its lightning current.

2. The grounding resistance of the lightning protection device of the distribution transformer is high.

3. Since the neutral point of the distribution transformer and the transformer shell are grounded, when the high-voltage lightning arrester discharges to the ground, the current enters the secondary winding of the transformer and the shell of the transformer again through the neutral line grounding, causing damage to the transformer.

In order to improve the lightning protection effect of distribution transformers, the existing lightning protection measures for distribution transformers mainly include reasonably selecting the lightning arrester on the high-voltage side, grounding the lightning arrester on the high-voltage side, the secondary winding and the neutral point grounding as two independent grounding body, but the above-mentioned existing methods all have defects to a certain extent.

Contents of the invention

In order to solve the above problems, the purpose of the utility model is to provide a distribution transformer lightning protection device with simple structure and improved reliability of lightning protection.

In order to achieve the above purpose, the distribution transformer lightning protection device provided by the utility model includes a high-voltage arrester, a low-voltage arrester, an anti-reflux device, a first grounding body, a second grounding body, and a third grounding body; wherein, one end of the high-voltage lightning arrester It is connected to the high-voltage side of the distribution transformer, and the other end is connected to the first grounding body; one end of the low-voltage arrester is connected to the low-voltage side of the distribution transformer, and the other end is connected to the third grounding body; one end of the anti-backflow device is connected to the distribution The neutral line of the electric transformer is connected to the shell, and the other end is connected to the second grounding body; the other ends of the first grounding body, the second grounding body and the third grounding body are connected to the earth grounding grid at the same time.

The anti-backflow device is a unidirectional conduction device including a diode and a thyristor.

The technical effect of the distribution transformer lightning protection device provided by the utility model is as follows: the anti-backflow device can be used to force the lightning current to only discharge to the earth grounding grid, thereby preventing the lightning current introduced into the earth from the arrester from re-discharging through the neutral line. The problem of entering the distribution transformer and damaging the distribution transformer. At the same time, the three independent grounding bodies from the first to the third can be used to appropriately reduce the inverse conversion voltage generated by lightning strikes, so that the distribution transformer can be better protected against lightning.

Description of drawings

Fig. 1 is a structural schematic diagram of a lightning protection device for a distribution transformer provided by the utility model.

In the figure, 1. Distribution transformer, 2. High-voltage arrester, 3. Low-voltage arrester, 4. Anti-backflow device, 5. First grounding body, 6. Second grounding body, 7. Third grounding body, 8. Earth ground grid.

Detailed ways

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments. The specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model.

As shown in Figure 1, the distribution transformer lightning protection device provided by the utility model includes a high-voltage arrester 2, a low-voltage arrester 3, an anti-reflux device 4, a first grounding body 5, a second grounding body 6, and a third grounding body 7 ; Among them, one end of the high-voltage arrester 2 is connected to the high-voltage side of the distribution transformer 1, and the other end is connected to the first grounding body 5; one end of the low-voltage arrester 3 is connected to the low-voltage side of the distribution transformer 1, and the other end is connected to the third ground. One end of the anti-backflow device 4 is connected to the neutral line and the shell of the distribution transformer 1, and the other end is connected to the second grounding body 6; the grounding grid 8 is set on the ground below the distribution transformer 1 In the soil, and the other ends of the first grounding body 5 , the second grounding body 6 and the third grounding body 7 are connected to the earth grounding grid 8 at the same time.

The anti-backflow device 4 is a unidirectional conduction device including a diode and a thyristor.

Since an anti-backflow device 4 is connected in series between the neutral line and the shell of the distribution transformer 1 and the grounding grid 8, the anti-backflow device 4 is a one-way conduction device, and the current flows from the neutral line of the distribution transformer 1. When the wire and casing flow into the earth ground grid 8, the anti-backflow device 4 shows zero resistance and conduction characteristics; High impedance and disconnection characteristics. According to the characteristics of the anti-backflow device 4, the lightning current can only be discharged to the earth ground grid 8, thereby preventing the lightning current introduced from the arrester into the earth from entering the distribution transformer 1 again through the neutral line and damaging the distribution transformer 1. question.

In addition, the first grounding body 5, the second grounding body 6 and the third grounding body 7 are connected to each other through the earth grounding grid 8, and the three independent grounding bodies can properly reduce the inverse conversion voltage generated by lightning strikes, thereby obtaining better protection against Thunder protection. In addition, the distance between the first grounding body 5 , the second grounding body 6 and the third grounding body 7 needs to be determined according to the level lightning protection requirements of the distribution transformer 1 .

It should be pointed out that the specific embodiments described above can enable those skilled in the art to understand the invention of the utility model more comprehensively, but it does not limit the invention of the utility model in any way. Therefore, although this specification has described the utility model in detail with reference to the accompanying drawings and embodiments, those skilled in the art should understand that the utility model can still be modified or equivalently replaced. The spirit and scope of the new creation, the technical solution and its improvement should all be included in the protection scope of the utility model creation patent.

Claims (2)

1. a distribution transformer lightning protection device, is characterized in that: it comprises high-voltage arrester (2), low voltage surge arrester (3), antireflux device (4), the first earth electrode (5), the second earth electrode (6) and the 3rd earth electrode (7); Wherein, one end of high-voltage arrester (2) is connected with the high-pressure side of distribution transformer (1), and the other end is connected with the first earth electrode (5); One end of low voltage surge arrester (3) is connected with the low-pressure side of distribution transformer (1), and the other end is connected with the 3rd earth electrode (7); One end of antireflux device (4) is connected with the neutral line and the shell of distribution transformer (1), and the other end is connected with the second earth electrode (6); Other one end of the first earth electrode (5), the second earth electrode (6) and the 3rd earth electrode (7) is connected with the earth ground network (8) simultaneously.

2. distribution transformer lightning protection device according to claim 1, is characterized in that: described antireflux device (4) is the one way conducting device including diode and controllable silicon.