||Lightning Monitoring System Solutions
|Computer technology in today's society, the increasing development of communication technology, all kinds of electronic equipment, a large number of applications, sensor to a nearby lightning strike the earth conductor to form over-voltage can be as high as several thousand volts, for microelectronic devices is lethal. The main invasive access LEMP a power line, all kinds of signal transmission lines, antenna and feeding line and into the system of pipes, cables, conductors and other invasive equipment systems bridge, resulting in electronic equipment failure or permanent damage. Therefore, the lightning impulse protection channel will be thunder and lightning in the invasion of stemming the flow into the land, and thereby to protect the electronic equipment of the head with. The main option is to use segregation, and other bits, clamp, are pressure, filtering, shielding, over-voltage over-current protection, grounding and other methods will be lightning over-voltage, over-current and lightning electromagnetic pulse device to eliminate outside, so as to effectively protect the devices. At present mainly uses gas discharge tubes, discharge gap, high-frequency diodes, varistors, transient diodes, thyristors, high and low pass filters and other components, depending on frequency, power, transmission rate, impedance, VSWR, insertion loss, bandwidth , voltage, current, etc., combined into the power cord, Antenna, signal line Series Surge Protective Device (SPD) is installed in microelectronic devices for external circuits, the ground access system according to the principle of sharing the earth ground before will not cause a ground counterattack. As long as rational design, installation qualified, surge protector lightning can be an effective defense.
1, monitoring system design based on an integrated mine
Integrated lightning protection monitoring system designed mainly uses the following criteria for the design reference.
(1) IEC61024 "Building Lightning Protection"
(2) IEC61312 "Lightning electromagnetic pulse protection,"
(3) B50057-94 "Lightning Protection Code for Design of Buildings"
(4) GB50200-94 "cable television systems engineering technical specifications"
(5) GB50198-94 "Civil closed-circuit TV surveillance systems engineering technical specifications"
(6) GB/T50311-2000 "building and architectural complex integrated wiring system design specification"
(7) XQ3-2000 "Meteorological Information System lightning electromagnetic pulse protection norms"
2, monitoring system, the principles of integrated lightning protection
A comprehensive monitoring system should be designed to take into account environmental factors, lightning, lightning activity patterns, the system equipment, the importance of the severity of the consequences occurring Leizai, respectively, take appropriate protective measures.
(1) in conducting a comprehensive lightning protection design, should adhere to a comprehensive planning, comprehensive management, optimization design, multiple protection, advanced technology, economic and reasonable, periodic inspection, random upheld the principle of integrated design and maintenance.
(2) integrated mine monitoring system should be designed with lightning directly stroke of lightning protection equipotential bonding, shielding, reasonable layout, use of ground system and installation of surge protection devices such as comprehensive protection measures. Must adhere to the prevention, safety first guidelines.
(3) The monitoring system should be based on an integrated mine-area thunderstorms grade equipment placed in the lightning protection zone of the different positions, different standard of protection.
3, monitoring, signal systems, building lightning directly stroke protection and earthing measures
(1) In each surveillance camera outside the top to install a stainless steel lightning rod to protect the equipment from lightning directly stroke hazard cameras.
(2) The lightning rod of the Yin Xiaxian make best use of steel columns Discharge line, conditions were not right, they can be used alone for more than 25mm2 copper pair to wear galvanized steel shield, and do insulation treatment, directly from the lightning rod tip the shortest path into the earth, in order to reduce the time of discharge lightning electromagnetic pulse radiation damage to microelectronic equipment system.
(3) Each outdoor camera and all the signals around the gun rod rack around, plus ancillary ground network to do a simple specifications as follows:
To net deepened 80CM, W 30CM, length 10 ~ 15M drains a
Polar, material specifications angle iron 4, 2.5M length, at intervals of 2.5 ~ 3.0M to fight one.
Connect to an extremely flat iron. . . . . .
(4) Each network easily be the basis of the nearest reinforcement connected with the house, to be effective lightning protection, connection material 25 mm2 multi-strand copper wire or ¦µ12 reinforced.
(5) Each power supply cabinet ground wire and the shell with 25 mm2 multi-strand copper wire with the ground network connection conduction.
(6) signal and the signal wire rack shell shield by 10 mm2 multi-strand copper wire grounding.
(7) 10 outdoor camera gun, signal cabinets, networks need to be a simple way for offices and other potential links (and villa-based ground network).
4, lightning electromagnetic pulse (LEMP) protective measures
Lightning electromagnetic pulse (LEMP) induced electromotive force generated by intrusion-channel signal superimposed on the line to generate transient high voltage, destroying various types of electrical equipment and micro-chips, and therefore mine projects need to focus lightning sensors to carry out an effective defense. In the design of an integrated mine when the channels should be more focus on protection, while making connections and sharing of equipotential grounding system.
4.1 Monitoring Center Monitoring System lightning protection measures
The total distribution switch control room to install a lightning Flow capacity Imax ¡Ý 40kA (waveform 8/20¦Ìs); nominal turn-on voltage Un ¡Ý 2.5Uc (Uc: Maximum working voltage); Ta ¡Ü 50ns response time, a single -phase surge protector SPD1, model: HD-D380C-XS40, in parallel, as a central monitoring equipment, the total power protection.
In the power equipment installed before or after a lightning-pass flow capacity of Imax ¡Ý 10kA (waveform 8/20¦Ìs); nominal turn-on voltage Un ¡Ý 2Uc (Uc: Maximum working voltage); Ta ¡Ü 50ns response time of single-phase surge protector SPD2, model: HD-D220CZ, lightning protection socket, as a second-level protection.
Outdoor camera gun camera shots dedicated power lines to install surge protectors, Imax ¡Ý 5kA (waveform 8/20¦Ìs); nominal turn-on voltage Un ¡Ý 2.2Uc (Uc: Maximum working voltage); Ta ¡Ü 50ns response time of a single model To HD-GVD/220V.
SPD connection wire should be short and straight, SPD connecting wires should not be greater than 0.5m, when the length of the bold diameter greater than 0.5m should be adequate.
4.2 Video signal transmission line of protective measures
Monitoring center video signal processing equipment and outdoor surveillance camera video transmission cables should be installed at both ends of the video signal SPD, model: HD-XH-GVD / A of 1 to protect the center equipment and camera.
5, shielding measures
(1) is to reduce the electromagnetic interference shielding the basic measures, should adopt the following measures: external shielding measures, the line laid in the right path, circuit shielding, appropriate combination of these measures.
To improve the electromagnetic environment, all the buildings together with the large-size metal parts should be equipotential bonding together and connected with the grounding device. The roof of metal surfaces, metal surface elevation, concrete and metal doors and windows within the framework of steel bars have to be connected to equipotential ground.
The need to protect the space, when using shielded cable, at least at both ends of the shield, and should do so in the lightning protection zone at the junction of equipotential connection. When the microelectronic devices the system requirements to do so only at one end of the potential connection, you can wear a metal pipe into shielded cable, metal pipe at one end so Equipotential.
Building the connection between the cable should be laid in metal pipes, these metal pipes from one end to the other side of the electrical linking should be across the board, and connected to various buildings and other potential connections bring. Cable shield should be connected to the belt.
(2) The practice of building or room in the large space shield is supported by metal objects, metal frame or reinforced concrete, reinforced the composition of these natural elements. These elements constitute a large space shield-shaped grille. Penetration of such shielding conductive metal objects should be nearest connected to ground potential to do so.
(3) The monitoring system equipment room location should be selected in the LPZ of the most advanced areas and to avoid the top three floors located within the building; days when the building part of the lightning surface grid size does not meet the requirements of anti-jamming system should be in Heaven Surface installation shield. Use of non-shielded cable, households before wearing metal pipe and buried in land in the horizontal distance of 10m or more. Who is subjected to conditions not to wear metal pipe buried in households, households should be extended the length of shielding tube or trestle, metal tube or both ends of the trestle bridge and in the lightning protection zone at the junction of equipotential bonding and grounding to be done.
(4) monitoring system equipment for the metal shell, the application of the shortest wire to connect it with other potential band connection. The case of non-metallic shell, shielding the building when the equipment is located does not meet the equipment, electromagnetic compatibility requirements, should be retrofitted with metal mesh or other shield the equipment shielding, metal net should be equipotential bonding equipotential bonding bands.
(5), computers, communication, monitoring the equipment room should be about 1m from the external walls of buildings to protect. When lightning directly stroke in order to prevent the building being leaked into the ground along the wall generate strong electromagnetic fields around the Yin Xiaxian damage microelectronic devices.
6, equipotential ground connection and sharing
(1) equipotential connection is important in modern mine technology, the protective measures. Will enter a monitoring center building various types of pipeline shield, rack, etc., etc. before entering the building connected to ground potential. Again before entering the device connected to equipotential ground second. The camera output of the outer layer of the coaxial cable and other lines entering the outer front of the building connected to equipotential ground.
(2) separate from the outer conductive devices equipotential bonding conductors connected to ground in order to reduce system equipment located in the building of metal structures and equipment or between equipment and devices due to lightning potential difference generated. The use of reinforced concrete structure of the building to connect all metal components to build a three-dimensional multi-connected network is to achieve the best choice for equipotential connection. To facilitate the construction of equipotential bonding should be embedded in some suitable place reserved for items such as potential connections.
Into the system of building various types of plumbing, heating and air conditioning ducts and other metal pipes metal outer office into the building should be done equipotential bonding, gas pipelines, after households should be inserted at a flange connecting two insulated side with the switching SPD connected indoor metal pipe may participate equipotential connection, and combined with the building of large-size metal pieces connected together, according to the requirements of GB50054 to do Equipotential connection, the access to the General, etc. potential to connect with, and reliable ground connectivity.
(3) In the building entrance, that is, LPZ0B with LPZ1 area at the junction of Main Equipotential connected to ground, in the follow-up of the lightning protection zone at the junction of the total equipotential bonding according to the methods of local equipotential connection, connecting to the main break should include the system equipment itself (including the exposed conductive parts may be), PE lines, cabinets, racks, electrical and electronic equipment enclosure, DC workplace, anti-static grounding, the outer metal shield cable, pipe, shielding slots, Surge Protector SPD grounding, etc. shall be the shortest distance from the nearest equipotential connection with this band direct connection. Basic approach should be used to connect network-based (M) structure, or star-shaped (S) structure. Net-type structure to connect the circular equipotential zone at intervals of 5m through the building wall should be reinforced, metal facade to connect with the grounding system. When using S-bonding network, the system of all metal components except in ground reference point, that is, ERP Department connections, should be common ground with the various components of the system has enough insulation (more than 10KV, 1.2 / 50¦Ìs).