Thunder and lightning mostly occur in the summer, which is a natural discharge phenomenon developed from the cumulonimbus cloud. There are many reasons for the cumulonimbus power generation. Most of them think that the granules in the cloud are rubbed with ice crystals or the granules cause the cloud droplets with a temperature below 0 °C to collide and freeze on it, and the surface flies off the debris when it touches the frost. Cause
Thunder and lightning mostly occur in the summer, which is a natural discharge phenomenon developed from the cumulonimbus cloud. There are many reasons for the cumulonimbus power generation. Most of them think that the granules in the cloud are rubbed with ice crystals or the granules cause the cloud droplets with a temperature below 0 °C to collide and freeze on it, and the surface flies off the debris when it touches the frost. Caused. When the two spies of the ice crystal are different, the hydrogen ion diffuses faster than the hydroxide ion and is negatively charged. The cold end is positively charged. Once the ice crystal breaks, the positive and negative charges will separate into two small particles. On the other hand, when the cloud droplets are frozen on the surface of the granules, the positive inner surface of the ice shell is negatively charged. When the shell is broken, the broken shells are positively charged and the surface of the granules is negatively charged, and the shells are lifted by small Pushing and accumulating in the upper part of the cloud, the granules accumulate at the bottom of the cloud due to heaviness and form a potential difference. When the potential difference reaches several hundred meters and several thousand volts, there is lightning thunder and lightning. This is lightning. The discharge between the clouds and the clouds, although there is a great sound and strong lightning, it is not harmful to people. Only the clouds will discharge the earth, causing damage to the buildings, electrical equipment or humans and animals. The damage is caused by the following: Three aspects caused:
(1) Direct lightning strike: It is the thunder cloud that directly discharges the ground object. Although the time of lightning strike is very short, only a few tenths of a fewth to a few hundredths of a second, but a large current passes, up to 100∽200 kA, so that The air temperature suddenly rises to 10,000 deg C, producing a strong shock wave, causing damage to houses and casualties. When a lightning current passes through a resistor or an inductive object, it can generate a large voltage drop and an induced voltage, destroy the insulation, generate a spark, damage the equipment, and even cause combustion, explosion, and further increase the hazard.
(2) Inductive discharge: It is the result of electromagnetic action caused by nearby lightning strikes. It can classify two kinds of electrostatic induction and electromagnetic induction: static induction is caused by the fact that when there are thunder clouds over the building, the building will induce the opposite load to the thundercloud. The electric charge, after the thundercloud begins to discharge to the ground, the charge in the discharge path is quickly neutralized, but the charge at the top of the building cannot immediately flow into the ground, forming a high potential, causing wires and metal equipment in the building. Metal pipes discharge, causing fires, explosions and personal accidents. Electromagnetic induction is the formation of a strong magnetic field when a lightning current enters the ground through a metal body, which can induce a high potential in the nearby metal conductor and cause a spark in the gap of the conductor loop. Article source: (http://Read.aspx?NewsId=19)
(3) Introducing high potential from overhead lines: When an overhead line strikes a direct lightning strike or a nearby lightning strike and induces an overvoltage, if it does not try to cause a large amount of charge flow to scatter into the ground on the road, it will be introduced into the house along the overhead line, causing damage to the house or electrical Equipment insulation breakdown and other phenomena. The power industry and the thunderstorm have achieved positive results, but they are far from over. Their lightning protection measures are:
(1) Install a lightning rod to prevent direct lightning strikes. The uppermost part of the lightning rod is the receiving end. It is usually made of galvanized or chrome-plated iron rods and steel pipes. It must be installed at a height higher than the protected building. The middle part is the guide line, and the lightning current is introduced into the ground. Made of galvanized steel wire or flat iron with a certain section. The bottom part is the grounding body. Connected to the lightning conductor to guide the lightning current to the earth and weld it with angle steel or steel pipe. Buried underground. When the thundercloud is close to a building or equipment, the static charge it induces can be neutralized by the tip discharge and the lightning to prevent lightning strikes. In the case of direct lightning strikes, it is also easy to introduce lightning current into the earth so that buildings or equipment are not damaged.
(2) Install the lightning protection horn clearance. This amount of simple lightning protection measures is used on the entry line of general buildings. Its gap is 2-3 mm. When there is overvoltage intrusion, the gap of the horn is discharged, and the lightning current is introduced into the earth. The effect of protecting the watt-hour meter and the current mutual stone sensor is very cheap and easy to install.
(3) Install lightning arresters. Commonly used is a valve type arrester. Its main components are spark gap and valve plate, and the resistance valve plate is made of silicon carbide. One end of the arrester is connected to the transmission line, and the other end is reliably grounded. Under normal conditions, the spark gap separates the line from the ground. When a lightning overvoltage occurs, the spark gap is broken down, the valve resistance decreases, and the lightning current enters the ground through the valve plate, so that the protected equipment is protected from damage. When the overcurrent drops, the resistance of the valve rises and returns to the normal state. Such arresters are mostly used for lightning protection of substations.
(1) In order to avoid spark discharge caused by static electricity induced by lightning, the protected metal part must be reliably grounded (except for the conductive parts of the wires and equipment).
(2) In order to avoid electromagnetic induction caused by lightning, sparks occur in the gaps in the closed circuit, and the metal objects in the electromagnetic field of the lightning current must have good contact to form a closed loop.
(3) In order to avoid the high potential of the cable and electrical equipment protection grounding device near the lightning rod when lightning discharge occurs. In case of electric shock or fire and explosion hazard, in addition to the metal of the cable, it must be grounded. The distance between the cable and electrical equipment protection grounding device and the grounding body of the lightning rod should be no less than 10 meters. Thunder and lightning mostly occur in the summer, which is a natural discharge phenomenon developed from the cumulonimbus cloud. There are many reasons for the cumulonimbus power generation. Most of them think that the granules in the cloud are rubbed with ice crystals or the granules cause the cloud droplets with a temperature below 0 °C to collide and freeze on it, and the surface flies off the debris when it touches the frost. Caused. When the two spies of the ice crystal are different, the hydrogen ion diffuses faster than the hydroxide ion and is negatively charged. The cold end is positively charged. Once the ice crystal breaks, the positive and negative charges will separate into two small particles. On the other hand, when the cloud droplets are frozen on the surface of the granules, the positive inner surface of the ice shell is negatively charged. When the shell is broken, the broken shells are positively charged and the surface of the granules is negatively charged, and the shells are lifted by small Pushing and accumulating in the upper part of the cloud, the granules accumulate at the bottom of the cloud due to heaviness and form a potential difference. When the potential difference reaches several hundred meters and several thousand volts, there is lightning thunder and lightning. This is lightning. The discharge between the clouds and the clouds, although there is a great sound and strong lightning, it is not harmful to people. Only the clouds will discharge the earth, causing damage to the buildings, electrical equipment or humans and animals. The damage is caused by the following: Three aspects caused:
(1) Direct lightning strike: It is the thunder cloud that directly discharges the ground object. Although the time of lightning strike is very short, only a few tenths of a fewth to a few hundredths of a second, but a large current passes, up to 100∽200 kA, so that The air temperature suddenly rises to 10,000 deg C, producing a strong shock wave, causing damage to houses and casualties. When a lightning current passes through a resistor or an inductive object, it can generate a large voltage drop and an induced voltage, destroy the insulation, generate a spark, damage the equipment, and even cause combustion, explosion, and further increase the hazard.
(2) Inductive discharge: It is the result of electromagnetic action caused by nearby lightning strikes. It can classify two kinds of electrostatic induction and electromagnetic induction: static induction is caused by the fact that when there are thunder clouds over the building, the building will induce the opposite load to the thundercloud. The electric charge, after the thundercloud begins to discharge to the ground, the charge in the discharge path is quickly neutralized, but the charge at the top of the building cannot immediately flow into the ground, forming a high potential, causing wires and metal equipment in the building. Metal pipes discharge, causing fires, explosions and personal accidents. Electromagnetic induction is the formation of a strong magnetic field when a lightning current enters the ground through a metal body, which can induce a high potential in the nearby metal conductor and cause a spark in the gap of the conductor loop.
(3) Introducing high potential from overhead lines: When an overhead line strikes a direct lightning strike or a nearby lightning strike and induces an overvoltage, if it does not try to cause a large amount of charge flow to scatter into the ground on the road, it will be introduced into the house along the overhead line, causing damage to the house or electrical Equipment insulation breakdown and other phenomena. The power industry and the thunderstorm have achieved positive results, but they are far from over. Their lightning protection measures are:
(1) Install a lightning rod to prevent direct lightning strikes. The uppermost part of the lightning rod is the receiving end. It is usually made of galvanized or chrome-plated iron rods and steel pipes. It must be installed at a height higher than the protected building. The middle part is the guide line, and the lightning current is introduced into the ground. Made of galvanized steel wire or flat iron with a certain section. The bottom part is the grounding body. Connected to the lightning conductor to guide the lightning current to the earth and weld it with angle steel or steel pipe. Buried underground. When the thundercloud is close to a building or equipment, the static charge it induces can be neutralized by the tip discharge and the lightning to prevent lightning strikes. In the case of direct lightning strikes, it is also easy to introduce lightning current into the earth so that buildings or equipment are not damaged.
(2) Install the lightning protection horn clearance. This amount of simple lightning protection measures is used on the entry line of general buildings. Its gap is 2-3 mm. When there is overvoltage intrusion, the gap of the horn is discharged, and the lightning current is introduced into the earth. The effect of protecting the watt-hour meter and the current mutual stone sensor is very cheap and easy to install.
(3) Install lightning arresters. Commonly used is a valve type arrester. Its main components are spark gap and valve plate, and the resistance valve plate is made of silicon carbide. One end of the arrester is connected to the transmission line, and the other end is reliably grounded. Under normal conditions, the spark gap separates the line from the ground. When a lightning overvoltage occurs, the spark gap is broken down, the valve resistance decreases, and the lightning current enters the ground through the valve plate, so that the protected equipment is protected from damage. When the overcurrent drops, the resistance of the valve rises and returns to the normal state. Such arresters are mostly used for lightning protection of substations.
Other measures for lightning protection:
(1) In order to avoid spark discharge caused by static electricity induced by lightning, the protected metal part must be reliably grounded (except for the conductive parts of the wires and equipment).
(2) In order to avoid electromagnetic induction caused by lightning, sparks occur in the gaps in the closed circuit, and the metal objects in the electromagnetic field of the lightning current must have good contact to form a closed loop.
(3) In order to avoid the high potential of the cable and electrical equipment protection grounding device near the lightning rod when lightning discharge occurs. In case of electric shock or fire and explosion hazard, in addition to the metal of the cable, it must be grounded. The distance between the cable and electrical equipment protection grounding device and the grounding body of the lightning rod should be no less than 10 meters.
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