Line type synthetic insulated zinc oxide surge arrester manufacturers for lightning protection of transmission lines

In recent years, due to the continuous deterioration of environmental conditions, the transmission line failures caused by lightning strikes have also increased, which not only affects the normal operation of equipment, but also greatly affects daily production and life. In the past few years, it was mainly concentrated in the southern mountainous areas. In recent years, there has been a trend of shifting to the northern plains. Lightning strikes have become the most important factor affecting the safe and reliable operation of transmission lines.

In order to reduce the lightning failure of the transmission line, various comprehensive lightning protection measures have been taken, such as reducing the grounding resistance of the tower, improving the insulation level of the line, using negative angle protection, and erecting a coupled ground wire, etc., and achieved certain results. However, it is difficult to reduce the grounding resistance of poles and towers for some lines distributed in high soil resistivity, and there are still no good countermeasures for preventing and controlling faults caused by lightning shielding.

At present, line-type synthetic insulated zinc oxide surge arresters have been widely used abroad for lightning protection of power transmission lines, and have achieved good results.

1　The basic principle of line lightning arrester lightning protection

When a tower is struck by lightning, part of the lightning current flows to the adjacent tower through the lightning conductor, and the other part of the lightning current flows into the ground through the tower. The grounding resistance of the tower is a transient resistance characteristic, which is generally characterized by impulse grounding resistance.

When the tower is struck by lightning, the potential at the top of the tower rises rapidly, and its potential value Ut=iRd+L.di/dt

When the difference between the tower top potential Ut and the induced potential U1 on the wire exceeds 50% of the discharge voltage of the insulator string, a flashover from the tower top to the wire will occur. That is, Ut-U1>U50, if the influence of the line power frequency voltage amplitude Um is considered, it is Ut-U1+Um>U50. Therefore, the lightning resistance level of the line is related to three important factors, namely the 50% discharge voltage of the line insulator, the intensity of the lightning current and the impulse grounding resistance of the tower. Generally speaking, the 50% discharge voltage of the line is fixed, and the lightning current intensity is related to the geographical location and atmospheric conditions. When no arrester is installed, the lightning resistance level of the transmission line is often reduced by reducing the grounding resistance of the tower. Grounding resistance is very difficult, which is why the transmission lines are repeatedly struck by lightning.

After the lightning arrester is installed, when the transmission line is struck by lightning, the shunt of the lightning current will change. A part of the lightning current flows into the adjacent tower from the lightning protection line, and part enters the ground through the tower. When the lightning current exceeds a certain value, the lightning arrester action will be added. Diversion. Most of the lightning current flows into the wire from the arrester and spreads to the adjacent tower. When the lightning current flows through the lightning protection wire and the wire, due to the electromagnetic induction between the wires, a coupling component will be generated on the wire and the lightning protection wire respectively. Because the shunt of the lightning arrester is far greater than the lightning current shunted from the lightning conductor, the coupling effect of this shunt will increase the potential of the wire, so that the potential difference between the wire and the top of the tower is less than the flashover voltage of the insulator string, and the insulator will not occur. Flashover, therefore, the line arrester has a good clamping potential effect, which is also the obvious characteristic of the line arrester for lightning protection.

In the past, lightning protection of transmission lines mainly used the method of reducing the grounding resistance of the tower body, which was relatively easy in plain areas. For mountain poles, longer radiation ground wires or deep wells were often used to add resistance reducing agents at the four tower feet. Increase the contact area between the ground wire and the soil to reduce the resistivity, and the ground resistance will decrease under the power frequency state. However, when it is struck by lightning, there will be a large additional inductance value due to the excessively long grounding wire, and the transient component L.di/dt of the lightning overvoltage will be added to the tower body potential, which greatly increases the tower top potential and is more likely to cause the tower. The flashover between the body and the insulator string, on the contrary, reduces the lightning resistance level of the line. Because the line lightning arrester has the effect of clamping potential, the grounding resistance requirements are not too strict, and it is relatively easy to realize the lightning protection of the mountainous line. After installing the lightning arrester, it is not difficult to find that the installation of the line lightning arrester has a very obvious effect on lightning protection.

2　The selection, installation and maintenance of arrester manufacturers

There are two types of line arresters, namely, with series gap and without series gap. Because of the different operation modes, they are different in structural design compared with power station arresters.

Pay attention to the installation of line arrester:

(1) Choose a transmission line tower with a lot of mine areas and easy to be struck by lightning, and it is best to install it on the adjacent towers on both sides at the same time;

(2) Lines arranged vertically can only be installed with up and down 2 phases;

(3) Try not to stress the arrester during installation, and pay attention to keeping a sufficient safety distance;

(4) The lightning arrester should lay a separate grounding wire along the tower, with a cross-section of not less than 25 mm2, to minimize the impact of grounding resistance.

Perform necessary maintenance after commissioning:

(1) In conjunction with the regular measurement of insulation resistance during power outages, the results should not change significantly over the years;

(2) Check and record the action of the counter;

(3) Tighten its fasteners to prevent loosening;

(4) Disassembled at 5 a, and perform a leakage current measurement under DC 1 mA and 75% reference voltage.

Yichang Hengyuan Technology Co., Ltd. is a professional manufacturer of European-style cable connectors, plug connectors, cable branch boxes, American elbow connectors, high-voltage vacuum circuit breakers, high-voltage load switches, lightning arresters, zinc oxide arresters, tank arresters, overvoltage protectors, Counters, monitors, heat-shrinkable cable accessories, cold-shrinkable cable accessories, T-shaped heads, wall bushings, European cable accessories, American cable joints, transformer neutral point protection devices, fuses, isolating switches, PT cable heads, elbows Manufacturers of type cable joints, 10kV outdoor terminals, switch cabinets, cable intermediate joints, cable accessories and other products