Rectangle Carbide Insert ,Carbide Milling Inserts,Carbide Tool Inserts,Sharpening Carbide Inserts SICHUAN TELOS NEW MATERIAL TECHNOLOGY CO., LTD , https://www.kenlarcutters.com
Second, the three forms of lightning damage: 1, direct lightning 2, inductive lightning (intrusion of thunder and lightning waves) 3, ground potential counter-attack lightning protection training materials 2 The first chapter of technical terms First, direct lightning thunder lightning is cloud lightning, refers to Thunderclouds discharge directly to the ground, buildings, or other metal bodies and produce force, thermal, and electromagnetic effects. The discharge limit of the lightning electromagnetic field is: uniform electric field: 20-30kV/cm Non-uniform atmospheric electric field: 30-40kV/m, maximum value 500kV/m. 2. Inductive lightning (or induced overvoltage) Inductive lightning (or induced overvoltage) refers to the overvoltage caused by lightning induced by electrostatic induction or electromagnetic induction in the vicinity of a wire or device.
Third, the ground potential counterattack refers to a high potential to low potential breakdown discharge a discharge phenomenon, referred to as counterattack.
Fourth, lightning rods and lightning rods (traditional) - 1759 Franklin Klein invented, will be led to their own thunder and lightning currents leaked into the earth to protect the protected objects from direct lightning strikes a needle lightning protection devices. The lightning rod is actually a lightning rod. Conventional lightning rods are generally composed of round steel or steel pipes, such as iron tower type, tubular type, and needle type.
5. The lightning protection device consists of a lightning arrester, a down conductor, a grounding device, a surge protector (SPD) and connecting wires.
Sixth, the lightning receptor directly receives lightning rod lightning rods, lightning conductors and lightning protection nets.
VII. Electrostatic induction Electrostatic induction: Due to the effect of thunderclouds, charges on the nearby conductors are induced with opposite signs to thunderclouds. Charges (positive and negative charges) in the pilot channels are quickly neutralized when the thundercloud discharges. The induced charge on the conductor is released and flows to both ends of the conductor to form an induced over-current and an induced over-voltage.
VIII. Electromagnetic induction As a result of the induction of lightning electromagnetic waves on metal wires and pipelines, the 3 waves of training materials for induced over-current and over-voltage lightning protection may invade the house along these lines, endangering personal safety or damaging the equipment. The moving wire cuts magnetic lines of force in a constant electromagnetic field, generating induced currents. The changing electromagnetic field cuts magnetic lines of force on the conductors to induce currents.
Nine, lightning surge due to lightning electrostatic induction, electromagnetic induction, direct lightning lightning over-current, over-voltage wave transmission in the wire as a lightning surge.
X. Surge Protector (SPD) Devices that discharge excessive current, suppress overvoltage surges, and function as protective devices (for surge protection surges, commonly known as "arresters") SPD meets two conditions: 1 Pass current; 2 suppress overvoltage.
XI. Grounding device The sum of the grounding body and grounding wire. Grounding body: Metal conductor buried in the ground and in contact with the earth. Divided into: horizontal grounding body (such as: flat steel 4034) vertical grounding body (such as: angle steel L503532500) 2 grounding line: used for equipment and grounding body connected line.
12. Ground Converging Ring A common grounding bus ring connected to various grounding wires around a room or equipment.
XIII. Ring grounding device A closed annular grounding body (including a horizontal grounding body and a vertical grounding body) buried in the ground around the building or other facilities at a prescribed depth.
XIV. Joint Grounding Connect independently separated lightning protection grounds, working grounds, protective groundings, and other metal grounding systems.
15. Ohmic resistance between the grounding resistor (R) grounding electrode and the remote grounding electrode with zero potential: 1 Power frequency grounding resistance: According to the resistance obtained by the power frequency current flowing into the ground through the grounding body. (R～)2 Impact grounding resistance: According to the current obtained through the inrush current flowing in the grounding body (eg experimental current)
Lightning protection training materials
First, the formation of lightning Lightning is a phenomenon of discharge in the atmosphere. During the thunderstorm season, the air near the ground heated up, and the rise of water vapor in the air was brought to high altitude. As the high air temperature is very low, the water vapor condenses into small droplets floating in the air. This gradual accumulation and increase of suspended water droplets results in the formation of dense clouds. In addition, cold air masses or air masses that move horizontally in the air rise above them. A large area of ​​concentrated cumulus clouds will also form on the interface. Observations have shown that in the formation process of concentrating clouds, some clouds have positive charges and others have negative charges. Their electrostatic induction to the earth generates opposite charges on the ground. When these cloud charges accumulate to a certain extent, The electric field strength between different charge clouds, or between the cloud and the earth, is enough to break the air insulation and start the free discharge. We call this free discharge a “pilot dischargeâ€, and the cloud discharge to the ground is the leading discharge. When the cloud jumps to the ground and gradually develops, when it reaches the ground (buildings on the ground, overhead transmission lines, etc.), a reversed main discharge from the ground to the cloud cluster will occur. In the main discharge phase, due to the conductivity Severe charge neutralization will cause a large lightning current (tens to hundreds of amps), and a strong flash and loud noise will occur. This will result in lightning. The discharge between the cloud and the cloud is called airborne lightning, also called cloud-to-cloud flash. The discharge between the cloud and the earth is called landmines, also called cloud flashes. The formation of thunder and lightning is often related to topography, geomorphology, atmospheric airflow and latitude of the Earth. In general, mountainous areas are thundering more than plains, and there are more low-latitude areas than high-latitude areas. As far as China is concerned, Leizhou Peninsula and Hainan Island have the most intense thunder and lightning activities in Guangdong. The average annual number of thunderbolt days is as high as 130, and most areas in the north of the Yangtze River are between 20 and 40 thunderbolt days. There are more than 20 in the northwestern region, and there are only about 10 in the new area.