||Green City Surveillance System Lightning Protection Solutions
|1, Engineering Overview
Gun control system consists of front-end camera equipment, video equipment and the control room shows the composition of transmission lines, the system uses a large number of integrated components, in the lightning strike occurs, the transmission lines, electromagnetic field sensors to the mine produced over-voltage can be as high as several thousand volts, for integrated components have greater hazards. The transmission line monitoring system at the LPZ0A many of the non-mine area. System alignment stage, does not consider the wiring Yin Xiaxian maintain sufficient distance from the mine, which are the safe operation of the system leaving a hidden danger.
Is generally believed that lightning protection measures segregation, and other potential, 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 elimination in the device periphery, and thus effective protection of various equipment. 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 potential counter-attack. Only reasonable design, installation qualified, surge protector lightning can be an effective defense.
Integrated lightning protection system designed mainly uses the following criteria for design reference.
(1) IEC61024 "Building Lightning Protection"
(2) IEC61312 "Lightning electromagnetic pulse protection,"
(3) ITU K25 "fiber optic cable lightning"
(4) GB50343 "Building lightning protection of electronic information systems technical specifications"
(5) GB50057-94 "Lightning Protection Code for Design of Buildings"
(6) GB50174-93 "computer room design specification"
(7) GB50200-94 "cable television systems engineering technical specifications"
(8) GB50198-94 "Civil closed-circuit TV surveillance systems engineering technical specifications"
(9) GB/T50311-2000 "building and architectural complex integrated wiring system design specification"
Second, lightning protective measures
(A) lightning directly stroke protection
Surveillance system with PTZ camera front-end equipment, including guns, no gun PTZ cameras, these devices installed in the outdoors, more prone to lightning strikes, so you want to install anti-lightning directly stroke system, need to do an independent outdoor lightning protection grounding. According to the minimum equipment requirements, grounding resistance: R <4¦¸.
1, monitoring system, front-end equipment, lightning directly stroke protection measures
(1) outdoor surveillance camera shot against lightning directly stroke facilities: in outdoor surveillance camera shot of the peak of the staff to install a lightning rod. Yin Xiaxian lightning rod to do the use of steel columns Discharge lines and in the pole base side and independent networks connected to ground lightning. Take pole height is 4 ~ 6 meters, lightning rod length is 1.5 to 2 meters, the use of ball method we can see the gun in the lightning protection of camera range. (See the next icon in the gun at the camera LPZ0B area.)
(2) Outdoor camera gun grounding and ground network
If the camera gun near the ground network, then the nearest ground wire to a nearby cited Grounding, if there is no way near the net, they should also
The construction of independent outside network, ground network, the program is as follows:
A, respectively, in the camera shots were planted around the pole grounding hot dip galvanized angle steel (5 ¡Á 50 ¡Á 50 ¡Á 2500mm), spacing of 5 meters.
B, angle steel grounding pole with 4 ¡Á 40mm flat composed of network-connected ring network.
C, the grounding system and the pole base connection.
(3) ground network construction procedure: the pre-construction we must first fully understand the construction site topography, geological structure, and then design and on-site set of the holes around the grounding conductors and connection grooves, and then carry out construction and installation. Note that to avoid the cable trench, pipeline and other conductive devices, the construction unit pre-construction to submit a written application and agreed to start to proceed. (Design using the resistivity of the soil to take 250¦¸ ¡¤ m.)
A, Trenching: the rational use of digging tools, to dig under layer by layer method, a trench depth of at least 0.8 meters, in order to be able to deepen the groove width is appropriate.
B, enter: use of appropriate tools to enter the angle grounding. Angle very depth of 0.8 meters below ground, that is grounding his head flat trench bottom.
C, connections: to install the grounding a good angle with the 4 ¡Á 40mm flat connected to form a mesh; all the connections are used welding.
D, the introduction of: the grounding system receives pole base.
E, backfill: First fill in the Pure Land, layer by layer compaction, finishing a good road.
Ground Grid Map
(B) the lightning protection
1, equipment front-end power protection of sensitive
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 anti-lightning,
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.
(1) front-end with a PTZ camera gun and lightning lightning protection measures: installation of modular front-end gun camera video, PTZ, power supply triple arrester 1, model: HD-CCTV-PVC / A.
(2) front-end non-PTZ camera guns lightning lightning protection measures: installation of modular front-end gun camera video, power supply combo a lightning arrester, model: HD-CCTV-PV / A.
(3) SPD grounding line: Lightning Protection Used for ¡Ý 2.5mm ² insulated multi-strand copper wire directly to the soft yellow-green and ground connections, ground lines and used as a lightning directly stroke Yin Xiaxian one another insulation between the pole , and try to be short and straight. Grounding wire should be placed within the pole.
2, transmission line protection
The transmission line monitoring system mainly fiber, coaxial and twisted pair. Mine should be in the system for different transmission line separately in different protection.
Optical fiber transmission line, because of itself is not a conductor of the lightning current is not sensitive, so do not consider the core line of lightning protection measures, but to strengthen the core should be grounded handle.
Coaxial transmission line, when done, should be installed at both ends of coaxial transmission line surge arresters, and transmission lines to wear a steel pipe laid underground, at both ends of the pipe lines were grounded, do equipotential bonding;
Twisted pair transmission line, when done, should be installed at both ends of transmission line surge arresters data signals, and transmission lines to wear a steel pipe laid underground, at both ends of the pipe lines were grounded, do equipotential bonding;
3, transmission line routing
Transmission line monitoring system is mainly the signal line and power cord. Outdoor camera power available from the terminal equipment at the introduction of, or from near the power to monitor the introduction.
Control signal transmission line and the alarm signal transmission line is generally used Copper shielded cord, set up (or laying) in the front-end and end -
Between the end.
Part of the proposed transmission line with a shield to wear steel cable or buried cable laying, maintaining the electrical connection pipe, so that pairs of protective electromagnetic interference and electromagnetic induction more effective. Wearing a metal tube such as a cable whole difficulty, they can enter the terminal and the cable front-end equipment, the former wearing a metal pipe buried in the introduction, but buried not less than 15 meters in length, in-home end of the cable metal jacket, steel pipe with the lightning protection grounding device connected. When conditions allowed, the communication pipe or overhead can be used at this time transmission cables and other lines of the minimum spacing of their groove and with other lines of the minimum vertical distance between poles, reference may be GB50198-94 "Civil Engineering closed-circuit TV surveillance technical specifications "to be laid. Such as: transmission cable and 220V AC electrical wiring of ditch (tunnel) at a minimum spacing of 0.5 m, and communication cables minimum spacing 0.1 m; transmission cable with a total of 1 ~ 10KV power line poles that the minimum vertical spacing of 2.5 m, 1KV The following power-line minimum vertical spacing 1.5 m, and broadcasting the minimum vertical spacing of lines 1.0 m, and communication lines the minimum vertical spacing of 0.6 m.
From mine point of view, sets of metal pipe laying method is best lightning protection, overhead lines are most vulnerable to lightning, and devastating large, spread wide, the first end of the device in order to avoid damage to overhead lines for transmission should be in each pole do ground handling, overhead lines and overhead cables hanging cable lines should be grounded in the metal pipe.
4, control room equipment, lightning protection
The main control room equipment, including monitoring center computers, video matrix, hard disk recorders, intercom systems, and power control center and so on.
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, it should face the days to install shield. Use of non-shielded cable, households before wearing metal pipe and buried in land in the horizontal distance of 10 meters. 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. Control 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. Computer, communication,
Control room equipment and buildings should be about 1 m from the external walls of protection. 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.
(1) power system control center of the lightning protection measures
Because 70% of lightning strike is a high-voltage power line from the intrusion, in order to ensure the safety of equipment and general power supply should be set three lightning protection.
a. In the control room where the building to install a total distribution box-type three-phase surge protector, pass flow capacity of 80KA (waveform 8/20¦Ìs), Model: HD-D380B-XL80, as the power supply first-class protection.
b. Sub-electric box in the control room to install three-phase (single phase) power surge protector, the biggest Flow capacity 40KA, Model: HD-D380C-XS40, as a second-level protection.
c. In the control room or monitoring equipment, UPS power supply installed before the series of single-phase UPS arrester, model: HD-UPSC4 / 4, parallel installation, power ¡Ü 5KW, with LC filter, low residual voltage output, as a third-level protection of power lines .
d. control room equipment before the installation of Flow capacity 10KA single-phase mine socket, model: HD-D220CZ, as a fine power lightning protection, power clamp and filter.
(2) The control room control, intercom system, lightning protection measures
a. control room video using 16 modular video arrester to protect the DVR video input port will not be Jihuai surge voltage, model: HD-XH-16GVD / A. Optical fiber transmission signals from the gun camera video, which do not consider the installation of surge arresters.
b. DVR with RS232 interface, RS232 interface, surge arresters to protect the hard disk video recorder serial port will not be Jihuai surge voltage, model: HD-XNET-D9.
c. All access to the control room of the control circuit installed control circuit arrester, model: HD-XC-YT / A.
d. wired intercom system is installed audio line arrester, model: HD-XH-GVD / A, only the host end of the installation of surge arresters intercom.
Lightning monitoring system diagram (omitted)
Monitoring system lightning protection grounding diagram (omitted)
3, shielding measures
1, underground lines, wires, pipes, PE lines and information lines of metal skin should be well grounded in-home side. Such as overhead or non-home pre-screened who should take in before the 20-meter indoor side pipe shield wire sets, and to shield connected with the mine to secure.
2, control room, should be metal computer desks, computer equipment, control equipment, lightning protection earthing metal shell and reliable connection.
3, outdoor camera gun to the decoder signal lines between the exposed and should set stainless steel or copper metal tube, and video and decoding of the gun metal shield enclosure
Metal shielding shell and the pole Yin Xiaxian reliable connection.
4, shielding to reduce electromagnetic interference with the basic measures, should adopt the following measures: external shielding measures, the line laid in the right path, the line
Shielding, appropriate combination of these measures.
5, in order 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 inside the steel framework for equipotential grounding must be carried out.
6, in 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.
7, 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.
8, in practice the 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.
4, equipotential ground connection and sharing
A, equipotential bonding is important in modern mine technology, the protective measures. Will enter the control center building, the shielding layer of various types of pipelines, machinery, etc., etc. before entering the building connected to ground potential. Again before entering the device connected to equipotential ground second. Outdoor camera output of the outer layer of the coaxial cable and other lines entering the building before the outer equipotential ground connection.
2, the outer conductive devices separate equipotential bonding conductor after the grounding to reduce the system equipment is 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 isoelectric
Bit connection construction, should be embedded in some places reserved for pieces of equipotential connection.
3, into the system of building various types of plumbing, heating and air conditioning ducts and other metal pipe metal outer office into the building should be done in the isoelectric
Digital connections, gas pipelines, after households should be inserted in the flange connections at both ends of an insulated connection with the switching SPD may participate in indoor metal pipe equipotential bonding, and combined with the building of large-sized metal pieces to connect together, according to the requirements of GB50054 to do equipotential bonding, the access to the General equipotential bonding zone, and reliable ground connectivity.
4, 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 bonding, connecting the main body 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 SPD grounding protection, 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 with a circular equipotential connection should be through the building wall at intervals of 5 meters of internal reinforcement, 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).
5, arrester connecting lead should be short and straight, SPD connecting wires should not be greater than 0.5 meters, when the length is greater than 0.5 meters should be an appropriate bold diameter.
6, the use of metal-containing components of the fiber optic cable, such as the tensile strength for the strengthening metal core, metal wave-layer, anti-rodent maintenance or repair of the outer layer of metal to use and reliable communication facilities, etc. shall be grounded, should be connected all the fiber optic cable along the connectors, etc. The tidal regenerator layer (metal layer), and the length of each side of the fiber optic cable directly to grounding terminals.