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With the rapid development of electronic information technology, information network has become an indispensable application tool in people's daily work and life. As an information network support point, the electronic information system room is responsible for the transmission, calculation and storage of electronic information. The data center computer room is an important category in the electronic information system room. It uses a large number of electronic technologies, communication technologies and computer technologies. It uses large-scale and very large-scale integrated circuits, and the informationization and networking are getting higher and higher, but They are often placed in complex electromagnetic environments, and some are even exposed to the outdoors, which can be subject to lightning strikes, lightning strikes, and intrusion into the device, damaging the device. Therefore, when establishing a data center equipment room, the lightning protection grounding system of the equipment room must be carefully considered to ensure reliable and safe operation of the data center equipment room.
The purpose of establishing lightning protection grounding in the data center equipment room is to avoid the invasion of lightning, thereby protecting the security of information system equipment and personnel. In order to prevent the electromagnetic pulse (inductive lightning) from entering along the power line of the equipment room, the equipment in the equipment room is damaged, and the lightning arrester, that is, the surge protector (SPD) is installed at the incoming line of each power distribution cabinet on the low voltage side. It is an electronic device that provides security for a variety of electronic devices. When the electrical circuit is suddenly subjected to a spike current or voltage, the surge protector can conduct the shunt in a very short time, thereby avoiding damage to other equipment in the loop by the surge. Due to the long distance from the underground low-voltage power distribution room to the fourth floor and fifth floor machine room, in order to solve the problem of residual voltage and cable induced voltage on the SPD, the whole power supply system of the project room is designed with three-level lightning protection device, the first-level SPD. The arrester is installed in the underground low-voltage power distribution cabinet, the second level is installed in the same floor UPS equipment room, and the third level is installed in the incoming line of the power supply cabinet of the equipment room. In this way, the entire building constitutes a multi-level power supply lightning protection, which can effectively protect the power supply system.
Since the power supply to the equipment room is introduced by the building's main power distribution. The lightning protection of the high voltage side of the power supply has been implemented by the power supply department. Therefore, for lightning protection of UPS power systems, we adopt the following lightning protection schemes:
1. Lightning protection of UPS power system
From the situation of the equipment room, the power supply line traverses the lightning protection areas at all levels. Considering the over-voltage resistance of various power equipment in the equipment room, we recommend the following power system lightning protection scheme to achieve good protection effect and More economical investment. Since the equipment UPS uninterruptible power supply equipment is an important equipment for providing a stable, reliable and high-quality power environment for the various electrical equipment in the equipment room, and is the main way for the mains supply to enter the equipment room, we will supply the power system. The focus of protection is on the protection of the UPS uninterruptible power supply.
In the computer room dedicated power distribution cabinet, UPS power supply to do two levels of lightning protection. The specific protective measures are:
Level 1 protection: Install a three-phase power supply lightning arrester (single-phase power supply lightning arrester) in front of the power distribution cabinet in the equipment room.
Secondary protection: Install a three-phase power surge protector (single-phase power surge protector) in front of the UPS power supply.
(Level 3 protection): Install a lightning protection socket at the important equipment.
2, installation, wiring
1. The function of the lightning protection device is to absorb and discharge the lightning current. All lightning protection products must be grounded.
2. The lightning protection device is connected in series/parallel between the protected device and the signal channel;
3. The input terminal (IN) of the signal lightning protection device is connected to the signal channel, and the output terminal (OUT) is connected to the protected device and is installed close to the protected device, and cannot be reversed;
Grounding body (including lightning protection, repeated grounding of AC neutral wire, protective earthing, joint grounding, cable metal outer sheath, and various natural grounding bodies, etc.), underground lead wires and connections of bare conductors on the ground, etc., should be reduced as follows Measures for electrochemical corrosion:
1 The grounding body (including the underground lead wire) shall be galvanized steel, cast steel, copper or graphite electrode;
2 reduce the DC operating current of the joint grounding system;
3 Protective earthing system should have no DC or AC current;
4 The cable should be insulated with an insulated outer sheath or with a metal outer sheath and an indoor grounding system;
5 When connecting two different metal wires (or metal rows), it should be welded as much as possible to ensure no false welding or virtual welding. When connecting with fasteners, the joints should be tinned. The lead wire of the grounding body is not allowed to be protected by steel pipe, and insulation measures should be taken.
When using the separate grounding method, it should be done:
1 The distance between various underground grounding bodies and underground bare leads should be >20m. Grounding piles should be provided at the grounding device.
2 Install protective grounding bars and joint grounding bars in the power supply room. 3 The distance between the outdoor lead wires of the grounding system and the lightning protection and discharge line of the house: when the height of the house is 30m or less, it should generally be >2m.
The joint grounding system shall be connected to the joint grounding bar according to the mechanical room classification. The connection spaces are as follows:
1 One pole of various DC power busbars to be grounded;
2 introduction frame, test frame, introduction test stand, test table, test bench test ground, and test instrument grounding;
3 The metal frame of each mechanical room is not connected to the AC power supply (the DC power distribution screen frame of the power supply room should not be grounded);
4 working grounding of telegraph machinery and automatic telephone repeater;
5 Introducing the insulated metal sheath of the cable and the metal shielding layer of the distribution cable;
6 security arresters for various communication machinery rooms (including discharge gaps, lightning arresters, etc.);
7 The rack that is prone to noise interference is grounded separately.
The protective grounding system is connected to the protective grounding bar according to the equipment, and the connection location is as follows:
1 AC switchboard, rectifier, other AC power equipment, and racks and casings for accessing AC power;
2 metal outer skin of the AC power cord;
3 The neutral line of the AC three-phase four-wire power distribution system is repeatedly grounded. It is not allowed to replace the protective grounding with the AC three-phase four-wire neutral.
With the increasing demand for lightning protection in security systems, many lightning protection manufacturers have taken the opportunity to expand the security market. However, these manufacturers do not fully understand the security industry; of course, in the case of increased market demand, many security engineers will also add lightning protection products. Installed in the monitoring system, this has caused the misunderstanding of lightning protection.
At present, there are two typical misunderstandings in the concept of "lightning protection":
1. Install the lightning rod on the security monitoring bracket. I believe that many people think that it is safer to install a lightning rod on the monitoring bracket to cause the lightning to be underground. Wrong! The outdoor isolated pole camera should be equipped with an independent lightning rod for the direct lightning strike. The distance between the pole and the independent lightning rod should be greater than 4.5 meters. Or the cement insulation material pole is more conducive to insulation, and the camera bracket uses engineering plastic brackets as much as possible to improve the insulation level.
2. Multi-point grounding provides a path for the ground potential to invade the security system, causing system damage. Multi-point grounding is suitable for strong power. In monitoring weak current systems, single-point grounding can protect products. Artificially making multi-point grounding of the security system, the "grid ground potential" is introduced into the security system through the ground loop, causing a voltage "surge." The weak current system has a low withstand voltage, and the pressure difference is too large at this time. Once the system is unable to withstand the damage, it will be devastating.
Machine room grounding device construction method
The grounding resistance standard of the equipment room shares a set of grounding devices, and the grounding resistance should be ≤1Ω.
When the safety protection grounding, DC working grounding, lightning protection grounding is divided, the grounding resistance value should meet the following requirements: 1 safety protection grounding, grounding resistance should not be >10Ω; 2DC working grounding, grounding resistance should not be >4Ω; 3 lightning protection grounding The grounding resistance should not be >10Ω.
Angle steel 50×50×5mm, length 1.5m～2.5m; angle steel for angle steel and angle steel connection, interval ≥4～5m, angle steel ≥40×4mm; lead wire adopts 50mm2 multi-strand copper core insulated wire or according to design regulations; The connection between the lead wire and the flat steel is welded, and the welding point needs to be treated with anti-corrosion treatment; the distance between the grounding body and the communication equipment room is 15m to 50m; the grounding body is buried to a depth of 1m; in the corrosion zone, the grounding electrode needs anti-corrosion measures.
The communication equipment room shall form a joint grounding network with the working ground, the protection ground and the lightning protection ground according to the principle of equalizing and equipotential.
In the comprehensive lightning protection system built in the factory room, whether it is lightning rod, lightning protection net, lightning protection belt, etc., or various lightning protection induction SPD, it can play an important part of lightning protection. It needs good lightning protection grounding. . Under certain soil and climate conditions, good lightning protection grounding depends on the shape of the lightning protection grounding device, the material and specifications of the grounding body and effective measures to reduce the resistance. Scientific calculations yield a variety of data that meets the requirements. Reasonable design can save manpower and material resources. Of course, there will be a certain gap between the calculation results and the actual situation. The size of the gap depends on factors such as the accuracy of the soil resistivity and the degree of uniformity of the soil. The basic spirit of Franklin's lightning protection principle is to pick up the lightning and lead the mine. The lightning interceptor draws lightning and can be quickly discharged into the ground to achieve the purpose of lightning protection and disaster reduction. Otherwise, although there is a good flashing device, there is no good lightning protection grounding, and it can not play a good lightning protection effect.
The lightning protection grounding device for the construction of the factory room includes the following parts:
1) Lightning receiving device: Metal rod (air receptor) that directly or indirectly receives lightning, such as lightning rod, lightning protection belt (net), overhead ground wire and lightning arrester.
2) Ground wire (down conductor): A metal conductor used to connect the lightning receiving device to the grounding device.
3) Grounding device: the sum of the grounding wire and the grounding body. Good grounding is the basis for stable, safe and reliable operation of the system.