Friday, June 14, 2019

Lightning rod

Lightning rod

How the sections lightning or lightning?

7 ^ 10 or 8 ^ 10 volts and voltage gradient may reach 10kv / cm
According to Simpson's view, when the speed of the wind is 800 cm / s in the shape of a peaceful slab
Of the cloud is faster and more light, and the discharge may end at this point, but this process is often repeated until it forms the lightning light and the time period of lightning is from millisecond to more than a second
Why use Lightning Arresrtor?
The lightning rod shall be used at the beginning and end of each line of 400,132 kV for the protection of equipment and equipment from the rise in voltages which occurs for the following reasons:
First: Surges that may hit the transmission lines because the transmission lines extend to large distances are more vulnerable to lightning
Second: the high voltages resulting from loss of pregnancy in the network.
Third: Closing and opening circuit breakers Circuit Breakers

Which consists of lightning arrestor?
The lightning rod consists of three main parts:
1 - Chinese body
2. Non-linear resistance
3. Spark gap
The resistance is made from Villite, Thyrite, and Varistora.
All of these materials are semi-conductors where resistance depends on the voltage value. In the case of the normal voltage are insulating materials (large resistance) and in increasing the voltage less resistance of these materials, which becomes connected
For effective protection, the lightening arrestor or ground wire tower must have a good ground

Where are lightning arresters installed?
The lightning rod is installed before the transformer to protect against overvoltage caused by lightening. The upper end of the lightning rod is connected to the medium voltage supply line with a conductor with the same area of ​​the line segment or the same type, by means of a casing and the bottom end of the lightning conductor is connected to the ground wire.
- Lightning plugs shall be installed at the beginning and end of the line.
- For electric stations, they are subject to the lightning protection system regardless of where they are located.
- Integrated urban areas appear to be important high-rise buildings where it is put on a block
Lightening them and acting in turn as a protective umbrella of stunts.
- In the desert areas, there are no high buildings so low-rise buildings are at risk of lightning and protection. Protection devices are placed over mosque minarets and high observation towers.

What is the idea of ​​lightning prevention work?
The lightning arrestor can be explained as follows: The spark plug consists of a Spark gap connected directly with a non-linear resistor,
The gap length is designed so that the normal voltage is not enough to cause its arc, but the overvoltage will cause a breakdown of air insulation. The spark is formed which makes the spark gap plugged in. (conducting) and since the characteristics of non-linear resistance that the resistance is significantly less with the increase of the voltage and thus will cause the collapse of the air insulation in the gap of spark and decrease resistance with the increase of voltage in the occurrence of what is short circuit in the power system, which causes the discharge of the lightning rod for high efforts during The ground and after the demise of the lightning surge will become a high resistance which prevents The occurrence of a collapse of the air in the sparkle or any non-conductive.

Protection of light transmission lines
For transport lines, there are other means of lightning protection in addition to the lightning rod, such as:
1. Ground wire protection

2. Protection using ground rails
1) Earth wire protection
Is a galvanized steel conductor located at the top of the electric towers. This connector acts to protect the transmission line from the clouds generated from the clouds and also to release the thunderbolt. The ground wire can be shortened to protect the transmission line as follows:
- Divide the amount of cargo in a bolt on the number of towers
- The connection of this wire indicates that the towers are connected in parallel and thus the lack of resistance
And therefore works on the speed of lightning discharges in the ground.
- Lightning protection itself from thunderbolt.
2) Protection using ground rails
Are rods of galvanized iron or copper and are buried in the ground and connected to the tower. The number of bars and burial depth depend on the required value of the ground resistance. The diameter is about 15 mm and the length is between 2.5 and 3.5 m in the ground.
Points 1 and 2 can be summarized as follows:
Earth wire is a wire that connects the top of the transport towers and connects the top of all the towers so that these towers are connected in parallel if the lightning strikes the transmission lines, they find the path with the least resistance is the ground wire, whose resistance as a result, as we said it made the towers transport as a conductor on
The parallel is known to reduce the total resistance obtained as a result, the lightning is discharged through this wire and from it to the towers connected to it and discharged to the ground through the ground bars connected to the lists of these towers or below them.

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