防雷工程中的等电位连接问题

防雷工程中的等电位连接问题 Equipotential connection problem in lightning protection engineering Introduction When we are detecting lightning protection, we usually only use ground resistance Test the instrument to measure whether the grounding resistance of each earthing point conforms to the relevant one Specification requirements, the grounding resistance is lower than the standard requirements, that is qualified, otherwise For unqualified, often neglected to check equipotential bonding. Even check Records are rarely recorded and rarely reported in the test report. In design Lightning protection project, designers are most concerned about the power, signal and other lines How many class lightning arresters are installed on the proper parts of the road and the equipotential connection is made The measure is only a brief description. In the construction of lightning protection works by Due to the limited working conditions, the equipotential connection is often avoided because it is difficult to realize Connection procedure. Equipotential and equipotential bonding Equipotential is to point to the space that needs lightning protection and equipment, be struck by lightning When the lightning overvoltage occurs, the parts of the system maintain the potential equal to that of the equipment No potential difference exists. In fact, it is difficult to reach the potential difference, Only the potential difference is relatively small to below the level of dielectric breakdown. Equipotential bonding is to put all the gold inside and around the building A substance such as concrete, steel, water pipes, gas pipes, and other metals Pipes, machinery, foundations, metal objects, and other large buried metal objects, Cable metal shield, protective earthing of power system, connection of building The ground wire and so on are all connected by electrical connection Welding or Reliable electrical connections 0, make the whole building a good one Potential body. When lightning strikes a lightning overvoltage, it is inside the building In general, it is equipotential, so that the equipment is not reversed by high potential An accident with a person struck by lightning. In addition, in the power line, telephone line, electricity Visual signals, cables, computers, signals, transmission lines, etc., and the outside world All connected metal wires shall be connected with suitable overvoltage protection devices Lightning arrester 0 and the earthing terminal shall be connected with the lightning protection earthing device of the building Direct electrical connection to make it equipotential In fact, quasi - Because there is lightning residual pressure at both ends of lightning arrester when lightning strikes 0. The role of equipotential bonding in lightning protection engineering The lightning strikes in nature mainly include direct lightning and lightning electromagnetic pulses Class. The direct lightning sound concurrency, with powerful electric Lightning flashes and thunder rumbles.. Flow, hot high temperature, strong shock wave, etc, hit the broken discharge channel Buildings, power lines, trees and human beings, livestock, etc.. Lightning electromagnetic pulse It happens quietly, and is not easy to detect. The consequences are serious. It is due to thunderstorms The electrostatic induction or discharge when electromagnetic induction causes the gold on the building A component such as a pipe, a steel bar, a power line, a signal line, etc. The voltage caused by discharge, which is mainly through the power line and signal line, antenna Line and ground potential counterattack are introduced into the chamber to destroy electronic equipment. The protection technology of direct lightning stroke has gone through !"" More than 1 of history has been Matured and widely recognized. It has a deeper impact on modern society, The greater the losses caused by induction, the lightning strike becomes the man placed in the lightning protection technology A major problem faced by a member of staff. At present, the protection of lightning electromagnetic pulse The main measures are shielding and diversion Thunder on the lightning current invasion channel The overvoltage and overcurrent are discharged into the ground in advance so as to protect the electricity The purpose of the sub device 0 and equipotential bonding. Equipotential bonding is an important part of lightning protection and electrical engineering Volume. Due to equipotential bonding, not only the building but also its interior The lightning protection capability of the equipment is greatly improved, and the design of lightning protection is also reduced The requirement of intermediate grounding resistance reduces construction investment and construction difficulty Low, especially for areas with high soil resistivity, is of greater significance. We often encounter lightning protection design in which the resistance requirement is less than that of the grounding resistance No, no matter what % Is it a power frequency resistance or an impact grounding? Resistance, just press % The frequency resistance is equal to % Impulse grounding resistance test Worry. In buildings !!" 2+)" 3 of the electrical equipment, its insulation, shock resistance Striking voltage as specified by the International Electrotechnical Commission " 43. When buildings When the lightning arrester is directly struck by lightning, the lightning current amplitude is (+ 56, it is in harmony with % The grounding resistance is generated (+ 56 voltage, This is the above-mentioned shock resistance voltage " 43 "-" - times. Shared ground ! " Shanxi Meteorological Quarterly The ##$! Period! The most important measures to prevent the insulation breakdown of power equipment are An overvoltage is arranged between the conductor with the insulating layer and the common earthing system Protector. An overvoltage protector is used to limit the presence of two objects A device for inter voltage shock, if overvoltage protection is installed The magnitude of the ground resistance of the common earthing device Is secondary, as long as the overvoltage is greater than the overvoltage protector The action voltage, which can cause the overvoltage protector to move in a flash Make no matter how much the voltage value is, and make the objects on both sides flash in an instant Short reach to equipotential, so as to achieve the purpose of lightning protection. A lot of practice has proved that as long as the equipotential connection is good, even if The actual grounding resistance is larger than the standard specification, and it can also play a very good defense Ray action. Equipotential connection in lightning protection engineering %& "Lightning and thunder and the equipotentialarrangement (using) the reinforcing bar of the building itself as a lightning protection device; and All kinds of exposed large metal objects inside and outside the building * heating, gas, self Water pipes, glass walls, curtain, etc. Make reliable electrical connections * equipotential Connect ) and the more referrals, the better. The more leads, the opposite flows through The smaller the lightning current at each conductor line, the smaller the corresponding drop The electromagnetic induction intensity around the assembly line. Similarly, lightning current decreases Small, it also causes an instantaneous voltage value that may cause a counterattack on the lead line Lower. Use steel column or column steel bar as lightning protection device The main reinforcement beam line, peripheral level equalizing ring * its main function is The feeder wires are connected in equipotential connection in the horizontal direction Steel frame And concrete bars should be connected to each other to form a large Faraday The smaller the vertical distance of the horizontal pressure ring is, the better. Horizontal mean pressure The ring can prevent thunder, It also plays a role in balancing the internal potential of each layer Use: first, balance the lead wire flow through different intensity of lightning current and produce The potential difference is two; it is balanced due to various leads and metal pipes Lightning voltage generated by the presence of distributed parameters. Higher than the radius of the ball * ! "Railings, # height on the outer wall of the door Larger metal objects such as windows should be connected with lightning protection devices. - any metal device that may be struck by lightning on the surface of the sky Equipotential connection with lightning arrester and lightning arrester grid nearby. %. Avoid equipotential bonding in induction mines %. &! Classification of lightning protection area International Electrotechnical Commission /01 '%' - '* lightning electromagnetic pulse' Protection A lightning protection device based on the interface partition is proposed Protection principle. Two thousand three hundred and forty-five Zone 6: objects in this area may be subject to direct lightning Therefore, all objects may conduct all lightning currents within the area Electromagnetic field does not decay. Two thousand three hundred and forty-five Zone 7: objects in this area are unlikely to be hit by lightning But the electromagnetic field in this region is not attenuated. 234: the objects in this area are unlikely to be hit by lightning The current ratio to a conductor Two thousand three hundred and forty-five 7 districts are further reduced. book The electromagnetic fields in the area may also decay, depending on shielding measures. 234, etc.: for the follow-up lightning protection area, according to the needs of the protection system The required environmental zone selection is used to further reduce the electrical power being guided Flow and electromagnetic fields. %. &! The equipotential connection between the exterior and the interface of the lightning protection section () the most effective way to prevent lightning waves from entering a wire is to turn it in The wires and cables are buried through the metal pipes, and the length of the metal pipes is introduced Should"! ! * For local soil resistivity ) both ends of the metal pipe shall be made Good grounding. (2) the shielding layer of the wires when they are introduced by shielded cables At least in both ends, as well as lightning protection area junction, and the ground network equipotential Connect。 ) the communication line shall not be worn in the same metal pipe as the AC line. Power line, phase, phase, phase and ground should be connected to lightning protection respectively The signal wire and the ground wire of the communication line must be connected with the corresponding lightning arrester. % &! Internal equipotential connection of lightning protection section (2) within the lightning protection section, there should be a closed loop equipotential Connecting belt. The belt should be at least With steel reinforcement Connect with the power supply grounding wire, DC grounding wire and safety grounding wire, The shielding ground wire is connected into a whole, so that the lightning protection interval is realized well Equipotential. All large internal electrical conductors, such as elevators, rails, and cranes Car, metal floor, metal door frame, facilities pipeline, cable tray Equipotential bonding should be connected to the nearest equipotential connection with the shortest route A band or other metal that has equipotential bonding. To further lighten the lightning sensation of the wire in the lightning protection section The wiring shall be as short as possible, and shall be arranged as large as possible in wiring The middle part of the building, the vertical wiring should be as far as possible from the building column, special Don't be an upright post on the outer wall of the building. These signal cables are available in hermetically sealed type The metal cable duct is shielded, Both ends of metal groove pipe should be equal to equipotential The connecting belt makes equipotential connection. %. Equipotential bonding in ground (of) buildings are fitted with a flash arrester in buildings Top or top ground, and use the steel bar of the building as the lead Line, so it is actually the communication system grounding, power work, grounding, security Full earthing, lightning protection, earthing The 8 systems are in common. The foundation of the building should be the main component of the building's ground grid Branch. In foundation cap, the pile bar, column bar and beam bar should be welded together Pass. At the base of the building At $9, ring along the base 4 weeks Terrane, and every other The $9 acts as a vertical grounding body and a ring grounding body Even. Outside the building, each column's main reinforcement is underground #&: 9 places are equal to The ring ground is connected. The grounding network should be made of various metal pipes and metal structures near the ground The pieces are connected underground. ) the equipotential bonding bands of each lightning protection section shall be in the shortest possible way ##$years! January, Wang Junping, et al. "Equipotential bonding in lightning protection engineering." Path connected to the ground network, (*) & "! -) is suggested in the star structure The potential difference between the metal and its vicinity is near zero. When the thunder strikes - type. Reticulate structure Type /. Equipotential bonding method, or adoption At the same time, the potential increases at the same time as the inside and the vicinity of the building Type and Method of type union. The body is equipotential, especially within the same lightning protection zone due to isoelectric 0, the conclusion bit connection realizes the high-precision equipotential, and fundamentally eliminates the side When the building is connected by equipotential connection, the whole building is flashover. Therefore, equipotential bonding is an important part of lightning protection system engineering For a uniform equipotential body. When lightning strikes, the quality of electronic equipment plays a key role, and fully embodies the modern lightning protection technology The potential difference of a component is much smaller than that of an unconnected state, especially the essence of a metal body. #! " $%& '(#) &* (+, -. $&/#0/1. 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