Measures To Protect Instrument Equipment Against Lightning Strikes.pdf 3 Pages

Volume 48, Issue 1, Petrochemical Automation Vo1.48, No. 1 February 2012 AUTOⅣA【TION IN PETRO- , 2012 Lightning protection measures for instrument equipment Shen Jinchen (Wuhan Jianan Petrochemical Company, Wuhan) Abstract: Briefly describes the relevant characteristics of the petrochemical industry and instrument equipment; analyzes typical The process, principle and hazards of lightning damage to equipment are explained in detail, and the methods and channels of lightning damage to instrument equipment are explained in detail. By analyzing several typical lightning strike damage accidents of instrument equipment in the refinery, we found common problems in lightning protection of instrument equipment; compared several effective lightning protection measures, and focused on the importance of the overall lightning protection plan for the system; Effective improvement and improvement measures are proposed for the lightning protection work of existing instrument equipment. Keywords: Lightning strike mode failure analysis Grounding system lightning protection measures CLC classification number: TP306.3 Document code: B Article number: 1007-7324 (2012) 01-0083-o3 Lightning is a sound, light, Electrophysical phenomena, traditional lightning accidents are also increasing, such as differential pressure and pressure transmitters, which have huge energy and extremely destructive power. Lightning strikes cause serious harm and consequences to the instrument system's level transmitter, fiber optic liquid level transmitter, gas alarm, and television monitoring. In areas with strong lightning strike hazards, cameras, etc., account for nearly 90% of petrochemical system lightning strike accidents.

Lightning protection for petrochemical instrument systems is particularly important. 2 Hazardous forms of lightning strikes 1 Lightning protection issues for instrument systems a) Direct lightning strikes. Thundercloud discharge directly enters the ground through buildings or ground petrochemical production equipment with high-temperature and high-pressure continuous production equipment. The powerful lightning current generates large mechanical vibrations in an instant. Most of the raw materials and finished products are flammable and explosive substances. Petrochemical power and high temperature and heat cause objects to be destroyed. When lightning current flows through industrial sites, it is divided into general industrial environment and explosive hazardous environment. When passing through objects, a large amount of resistance or inductance will be generated, so the installation location is divided into controlled indoor environment and outdoor on-site environment. The voltage drop and induced voltage will destroy the insulation and generate sparks, causing on-site instruments installed in explosive hazardous environments to include explosion-proof type, intrinsic combustion, explosion, etc. Safety type and other explosion-proof types. Instruments with different explosion-proof types, b) Ground potential counterattack. The characteristics and methods of high-electricity lightning protection of tens or even hundreds of kV are also different. The voltage installed in the control room is connected to the ground along the down conductor and flows into the ground grid. Due to the impact of transient high voltage on the intrinsic safety-related instrument system, the lightning protection project should also consider this strike, resulting in a local potential increase at the grounding point. The structural characteristics and corresponding methods of the electrical safety instrument system appear in the ground network. The petrochemical level difference may lead to backlash and damage to electrical equipment. The weakness of the potential difference instrument system equipment in the ground network: it can also generate step voltage, which directly endangers human life. a) Most of the instrument system equipment is composed of integrated circuits, and c) it induces lightning.

The basic characteristic of induction lightning is that the intervals between lightning strikes are very small. A very small overvoltage will cause counterattack flashover. The concentrated area produces the result of electromagnetic induction, which can be divided into electrostatic induction and electrostatic induction. Power and signal lines in circuits usually have micro-support structures. There are two types of magnetic induction. Induction lightning is not as violent as a direct lightning strike, but it causes these support structures to become overheated and buckle when struck by a surge. The probability is much higher than a direct strike lightning strike. A direct lightning strike can only deform the circuit, causing lines that should be isolated from each other to come into contact with each other, and the induced overvoltage caused by lightning can form an internal short circuit, causing the integrated circuit to fail. Metal conductors such as power lines and telephone lines are transmitted to long distances, causing b) The operating voltage of electronic systems is low, generally 3, 5, 12, causing a wide range of damage. 24V etc. Any impact that exceeds the working voltage (such as lightning overvoltage, usually the lightning strike does not hit the building, but the internal voltage of the building) may cause the electronic system to malfunction or be permanently damaged, and the affected electronic equipment will still be destroyed. Scientific research shows that the system operates stably even if a lightning strike occurs. Without directly hitting the building, it will also cause damage to the microelectronic equipment in the building. As the degree of networking of computer systems continues to increase, its defense will be damaged, because as long as the center point of the lightning strike is within the radius of the building, the lightning strike and surge voltage resistance will be damaged. The ability is getting lower and lower, especially within a comprehensive range of 2km, lightning will produce extremely strong electromagnetic fields. All network switches, servers, computers, and monitoring systems connected by wiring pass through this electromagnetic field. The power supply lines, network and signal line systems, and terminal equipment are more susceptible to lightning damage.

Since these devices are at the core of network operation, once a lightning strike or surge occurs Manuscript received date: 201i-09-28. Current intrusion will cause extremely serious consequences to the operation of the entire network. Author introduction: Shen Jinchen (1973), female, from Xiaogan, Hubei, graduated from Wuhan Guo in 1994, and may even cause communication interruption and data loss. Currently, I major in instrumentation at the Municipal Radio and TV University, majoring in industrial electrical automation and electrical engineering, and have been engaged in instrument maintenance. Petrochemical Automation Volume 48, etc., a surge will be generated on the line due to electromagnetic induction. Install lightning rods, lightning protection belts (nets), metal masts of buildings, metal pressure, and enter the equipment input ports in the building along the lines. As a result, towers, etc. were not used to shunt air-termination devices; the grounding system was not standardized, and electronic equipment was burned. The meter system does not form an equipotential connection; it does not form an electromagnetic blockade; electrostatic induction is the induction of charges in the clouds that makes the top of the building (shielded); there is no reasonable wiring; and no SPD is installed. Charges with opposite polarity accumulate and discharge when the electric field intensity reaches 25~30MV/m. After the discharge process starts, the comprehensive engineering of the discharge path. In construction projects, the charges in buildings, electrical appliances and instruments are quickly neutralized, but the charges on the top of the building are of opposite polarity. Lightning protection includes lightning protection, shunting, voltage equalization, grounding devices, and equipotentials that cannot enter the ground in time, thus forming a very high potential, which can easily break top connections (devices, areas, buildings), building shielding, and power supply and distribution systems. If it is damaged, the metal equipment will be burned internally or cause a fire.

System surge protector installation, etc. d)Electromagnetic induction. Electromagnetic induction is the basic principle of lightning protection when lightning current passes through metal: providing a reasonable low-impedance path for lightning (including lightning conductors to enter the ground, forming a rapidly changing strong magnetic field, causing electromagnetic pulse radiation) to discharge to the earth. , and induce overvoltage in nearby transmission lines or equipment, causing the lines to randomly select discharge channels, that is, controlling the leakage of lightning energy or the breakdown of the insulation layer of the equipment, resulting in power supply interruption or equipment damage. Put and convert. Lightning protection measures for buildings and electronic equipment mainly adopt e) switching overvoltage. The inductance and capacitance in the power supply system can be discharged in the power supply a) by using the following methods: turning on or off the load, short-circuiting the power line, etc. Use lightning rods, lightning protection belts and lightning protection nets to generate pulse high voltage on the line, which can reach 3.5 times the line voltage. The lightning current is led to the earth along the down conductor, preventing lightning from directly hitting the building and damaging the equipment. The damage effect is the same as Lightning strikes are similar. items and equipment. 3. Lightning surge overvoltage invades the channel b) Shielding of the equipment. To prevent surges from AC power supply lines and information systems, which refers to a sudden instantaneous overvoltage in a circuit or a surge transmitted through the network that damages equipment and endangers personnel safety, the current phenomenon is introduced. It occurs from direct lightning strikes, lightning electromagnetic induction, lightning external transmission lines and cables should use closed metal trunking or through metal strikes, electrostatic induction, power supply voltage fluctuations, electromagnetic field interference, etc. Pipe laying, and conduct reliable research on metal trunking and threaded metal pipes to clearly understand the channels through which lightning surge overvoltage invades the equipment, and conduct appropriate multi-point grounding to minimize the risk of induced lightning strikes. Install corresponding equipment on the intrusion channels. Protective equipment can prevent equipment accidents from invading power surges.

Computer systems all metal into electronic communications equipment for the purpose of lightning surge protection. Lightning strike electrical conductors, including power cables, communication cables and signal lines, are all shielded by surge overvoltage and damage equipment. There are three main forms: shielded wires or metal tube shielding. During the construction of the computer room, the building a) surge overvoltage is used to penetrate the equipment's steel mesh and other metal materials through the equipment's power supply lines, forming a shielding cage in the equipment room, burning the rectifier switching power supply of the equipment, and then causing the equipment to It is used to prevent external electromagnetic waves (including lightning electromagnetic waves and electrostatic induction equipment from losing power and stopping working. Should) interfere with the equipment in the computer room. b) Surge overvoltage is connected to the network, signal and security through equipment. 6) Equipotential connection (for non-charged metal bodies). The data control lines of the system in the computer room are penetrated into the equipment, causing damage to the equipment. There are metal objects, including cable shields, metal pipes, metal doors and windows, C) Ground loops passing through the equipment destroying the equipment. Lightning strikes electrically connect metal components such as equipment casings to equalize the potential. Near the building, or hitting the external lightning protection device of the building, lightning d) grounding. In order to ensure the stable and reliable current of the computer network system is discharged to the ground along the down leads, it is necessary to enter the site and construction work to solve the environmental electromagnetic interference and static electricity hazards. The potential difference of the equipment grounding bar in the equipment will be extremely large. . This potential difference will better ground the system. Destroy the equipment through ground potential counterattack. e) Lightning surge overvoltage protection. As long as the signals of electronic equipment are installed on the three channel lines and power lines that lightning surges must pass through to destroy the equipment, corresponding overvoltage protectors should be installed on them, and corresponding equipotential connections should be adopted and lightning protectors should be installed on them to prevent overvoltage. Destroy the linear effect, filter out the excessive pulse voltage on the line, and protect the equipment from damage can basically be avoided.

For one need protection from being damaged by overvoltage. For systems where the main protection device is zinc oxide pressure-sensitive protection, only the power lines, signal lines and other resistors, fast clamping diodes, etc. that enter and exit the system can be combined as needed to form a corresponding surge protection device (SPD) that is installed to the ground. ), it is a complete lightning protection device when struck by lightning. The potentials between various parts in the system will be approximately equal, so f) reasonable wiring can be avoided. When the lightning current is connected to the shunt, the down-line is avoided to cause damage to the equipment. When leaking to the earth, due to electromagnetic coupling, an electric potential, that is, a surge, will be induced on nearby conductors (wires and cables). The value of this surge is inversely proportional to the square of the distance from the down conductor to the Wuhan Petrochemical Plant because there are many old devices in the early stages of construction. In order to reduce lightning protection, and at the same time, some instrument system lightning protection projects are designed to reduce surges on cables. When arranging power lines and signal lines, work should be carried out according to specifications as much as possible. Therefore, there are the following main problems: not staying away from the lightning protection down conductor. Issue 1 Shen Jinchen． Lightning protection measures for instrument equipment 85g) Install SPD. At the incoming end of all connections in the building, g) for combustible gas alarms, SPD can be installed near the equipment, at the interface of the lightning protection zone, etc. on the terminal block as needed. Install a 0.25~0.5A fuse. 5 Lightning protection implementation plan h) After each lightning strike, the system cards must be carefully checked. At present, most of the instrument control systems of the factory have adopted equipotential analysis for reasons.

Grounding method, but comprehensive protection is the consensus lightning protection policy. Instrument protection 6 Conclusion The lightning protection system is also a systematic project. Lightning protection measures for the instrument system of the entire factory's production equipment must be taken. Multiple surveys must be conducted on the grounding status of the instrument equipment in the project, and existing problems must be fully considered in the design stage. If after the construction of the building is completed, it will be difficult to implement some protective measures to rectify and correct hidden faults by sorting out the main causes. The lightning protection effect needs to be verified through actual testing. The specific methods are as follows: Inspect and take different preventive measures according to the characteristics of different instrument systems. a) The grounding system should be inspected and implemented before the thunderstorm season every year to minimize the damage to instrument equipment caused by lightning strikes and ensure instrument maintenance. Mainly check whether the connection is tight, whether the contact is good, and whether the system is operating normally. Check whether there is corrosion on the grounding down conductor and whether there is any abnormality on the ground near the grounding body. References: If necessary, the ground should be dug up to randomly check the corrosion of hidden parts underground, such as [1] China Machinery Industry Federation. 2010 Building Lightning Protection Design Code Es]. Beijing: China Planning Press, 2011. If problems are found, they should be dealt with promptly. [2] China Petroleum and Chemical Industry Association. --2002 Automation Instrument Engineering b) The rectification of the old system must be stepped up. The old system did not have safety construction and acceptance specifications Es]. Beijing: China Planning Press, 2003. Isolation measures - lightning protection grid; limited by the construction regulations at the time, it was followed by [3] Chemical Industry Branch of China Engineering Construction Standardization Association. The 2007 automatic ground system is incomplete; the equipment is aging, and some grounding copper bars and screws are in the construction quality acceptance specifications of biochemical instrumentation [S]. Beijing: China's planned publishing house is severely corroded by rust.

Society, 2008. o) On-site instrumentation and control systems should be considered during the instrument design process [4] China Electricity Council. --2006 Specifications for Construction and Acceptance of Grounding Devices in Electrical Installation Projects[S]. Beijing: China plans to publish issues on compatibility and matching, as well as lightning protection measures for buildings and equipment. Society, 2006. d) The grounding resistance of the grounding grid should be measured once a year. [5] Ye Xiangdong. Lightning protection engineering design of petrochemical instrument system [J]. The petrochemical industry has responded to the aging of operating lightning arrester components before the annual thunderstorm season, 2008, 44(O2): 1-9. A chemical tester should be used for a test; appearance patrols should be strengthened during thunderstorm seasons [6] Liang Dong. Lightning protection of instrument systems[J]. Petrochemical Automation, 2004, 40 views, if the lightning protection module display window is found to be red, it should be dealt with in time. (O6):19-21． e) Install surge protectors for power supply and signals. The equipment was struck by lightning [7] Yu Wu, Zang Geng, Zhao Datong. Basics of modern lightning protection technology[M]. Beijing: Investigation and analysis of the damage should be carried out after the Tsinghua attack. The analysis includes: Xue Press, 1995. [8] Zhou Zhimin, Zhou Jihai, Ji Aihua. Lightning protection and grounding technology for electronic information systems[M]. Whether there are traces of breakdown and flashover in various electrical insulation parts and whether they are scorched. Beijing: People's Posts and Telecommunications Press, 2004. Odor, damaged parts of equipment components. [9] Zhang Xiaoqing. Lightning protection of electronic equipment in buildings[M]. Beijing: Meteorological Bureau f) Installing lightning protection barriers between the automatic control instrument system and the outside world, 200O. isolation.

Install the peak current recording card, record the measurement data, and measure [1O] Liu Jinhai, Li Zheng. The impact of lightning strikes on instrument systems IJ]. The peak current data of oil and gas field surface engineering are recorded and archived. Cheng, 2005(1O): 24-26. Application of Weidmüller products in petrochemical projects Weidmüller won the bid for the 10Mt/a refinery and 1Mt/a ethylene project of PetroChina Fushun Petrochemical Company on June 27, 2008, and provided @CB series wiring for the project boxes, relay boards, safety relays and related products. Fushun Petrochemical's 10Mt/a refinery and 1Mt/a ethylene project are major projects of China National Petroleum Corporation in eastern China, with a total investment of 2.1 billion yuan. The completion of the project will improve the comprehensive strength of China National Petroleum Corporation, help China Petroleum realize the optimal allocation of crude oil resources in Northeast China, promote the optimization and adjustment of the layout and structure of the refining and petrochemical business, and accelerate the implementation of the three strategic resources, market and international change. Weidmüller's junction box products are in a leading position in the world in terms of quality and reliability. Its @CB series junction boxes are widely used in petrochemical projects, especially successfully used in the Fushun large ethylene project, and have received praise from the owners of Fushun Petrochemical Company. recognized. Weidmuller products are widely used in Fushun Large Ethylene, including traditional terminals, power supplies and other products.From the traditional petroleum and petrochemical industry to the emerging solar and wind energy industries, Weidmüller has been at the forefront of technology development and application, and has been working hard for the development of the Chinese market! Weidmüller Electric Connection International Trade (Shanghai) Ltd.