The effective work of building intelligent system depends on the normal power supply, especially the computer room should not be powered off, because the computer room is the head organ of intelligent building. For the general power distribution system of intelligent buildings, normal power failure or accident power failure is allowed, but not for the central computer room. Power supply solutions for the integrated wiring room: first, the front-end AC power supply attracts two mains power, and when conditions permit, generators can be added to become multi-channel power supplies to improve power supply reliability; The second is to install uninterruptible power supply UPS in the computer room and attach a certain DC battery pack as a backup power supply to ensure power supply. The former is a traditional way to improve the reliability of power supply, and the latter is a way that is more and more widely used with the rapid development of information technology in recent years.
There are two UPS power modes to choose from. One is online, that is, UPS is always in the power supply state and always works, and UPS replaces the commercial power to supply power for computer network equipment. Second, the backup mode means that computer network equipment usually relies on mains power supply, and only when mains power fails, it immediately turns to UPS for power supply. There is a zero-crossing problem of standby power supply, that is, when the mains power is cut off, no matter what closing method, it is impossible to avoid the problem of instantaneous power failure. The specific method is divide and conquer: if it is a normal power outage, it must be notified in advance and UPS can be put into operation in advance; If it is a fault (short circuit, grounding) power failure, because the current on the inductor and the voltage on the capacitor cannot jump, the automatic access of UPS can be set to be less than the tripping current value, that is, the UPS can be turned on before the circuit is disconnected.
UPS power supply is developing in the direction of high power, low noise, intelligence and networking, which is exactly what the central computer room needs. High-power UPS power supplies (such as 20, 30, 60KVA and above) have parallel redundancy function, and the new hot-swappable and modular battery array further improves the reliability of power supply. This is because the "array structure" has been proved to be beneficial to the improvement of reliability when it was used in the "disk array" of computer networks.
Floor design of integrated wiring machine room: application of anti-static floor
Anti-static mainly refers to the timely elimination of static charges generated by various parts of the computer room. Friction electrification is a natural phenomenon, and the accumulation of static electricity will cause accidents and endanger electronic equipment and personal safety. Therefore, the computer room should use anti-static floor to discharge static charge through grounding. The floor is generally 0.3m above the ground. In order to ensure the construction quality, the computer room project should be undertaken by a unit with computer room construction qualification.
Lightning protection design of integrated wiring machine room: lightning protection and grounding design of machine room
A large number of electronic equipment in the central computer room have low working voltage, many precision equipment and poor lightning resistance. Once you lose money, you often lose a lot. Therefore, the lightning protection level here is high, and measures to prevent all kinds of lightning strikes need to be taken. There are many forms of lightning strike, and the lightning protection measures in the computer room are mainly aimed at direct lightning and induction lightning. The general practice is to set lightning rods and lightning belts on the roof to prevent direct lightning; Connect the main reinforcement of the whole structure in the building with each other to form an equipotential faraday cage and an equalizing ring to prevent side lightning strike (the equalizing ring is formed by connecting the ring beam reinforcement with the main reinforcement in the column at a height of 30 meters or more every three floors of the high-rise building); The foundations of buildings are connected with each other through pile conductors, forming a good grounding and ground potential distribution in the building. In addition, the metal equipment on the surface of the building and the metal pipes entering the house are well connected with the grounding grid to ensure the equipotential in the building.
In order to prevent high-voltage lightning waves from invading the equipment in the computer room, various overvoltage protection devices can be adopted at the front end of the equipment in the computer room. For example, setting a three-level lightning protection device in front of network equipment can effectively shunt and limit voltage and prevent the invasion of induced lightning waves. Three-level lightning protection device refers to the front end of power terminal, UPS terminal, server or distribution frame. In addition, lightning arresters should be installed at the entrance of antenna feed, signal line and data communication line which are introduced into the room outdoors.
Grounding system includes lightning protection grounding, AC working grounding, DC grounding, PE protection grounding, shielding grounding and anti-static grounding, and the latter three systems can be connected with each other. Generally, common grounding mode is adopted, that is, lightning protection grounding, protective grounding and working grounding are directly connected to the grounding network, and the total grounding resistance should be less than 1 ohm, which is called zero grounding resistance. When conditions permit, special grounding devices can also be set up.
In digital circuits, the logic grounding that provides equipotential surface and the signal grounding that provides reference potential in analog circuits become DC grounding. The reference potential of DC grounding system is taken from the total equipotential copper bar. In the project, the insulated copper core wire with a cross-sectional area of 35 square millimeters can be led to the integrated wiring equipment through the protective tube as DC grounding.
There are many AC and DC filters in electronic equipment, which are used to prevent the interference voltage of various frequencies from invading through the power line and not affect the work of low-level signal devices. The grounding of AC /DC filter is called power supply grounding. The power grounding system leads the insulated copper core wire with the same section as the phase wire from the distribution box to the integrated wiring equipment. In the TN-S five-wire system, this ground wire is connected to the N-wire (neutral wire).
Shielded grounding and anti-static grounding are to solve the problems of electromagnetic radiation and electromagnetic interference. With more and more high-frequency communication facilities in intelligent buildings, anti-interference becomes more and more important. Electromagnetic interference is parasitic electric energy radiated by electronic system, which will reduce the accuracy of data transmission, increase the bit error rate, affect the definition and cause electromagnetic environmental pollution. In order to prevent external electromagnetic interference, the shielding wire or threaded metal pipe inside and outside the electronic equipment shell and equipment is grounded, and the whole process is shielded, which is called shielding grounding. Generally, the environment of computer room is relatively dry, which is easy to generate static electricity, and then it will interfere with electronic equipment. Therefore, the grounding used for this purpose is anti-static grounding. The general practice of shielding grounding and anti-static grounding is to lead the PE integrated wiring trunk from the main equipotential copper bar in the building, and set equipotential copper bars for integrated wiring on each floor, and the shell, metal pipes and anti-static grounding of electronic equipment are connected with the equipotential copper bars.
In addition to the above measures, the safety facilities of the computer room in the integrated wiring should also include access control, anti-theft, closed-circuit television monitoring, firewall software, fire alarm, etc.
Design standard of integrated wiring room
The design stage of the central computer room can be divided into preliminary scheme design, civil engineering design, layout and decoration deepening design, design joint review and completion drawing. The preliminary planning should determine the composition, main functions and macro requirements of the computer room. Civil engineering design determines the location, area, shape, height, etc. Deepen the design and determine the plane and elevation layout of the computer room, the specific decoration method, the selection of electromechanical equipment and lighting lamps. The design of the central computer room is mainly based on GB50 174—93-93 "Design Standard for Computer Rooms" and other specifications. The main contents involved are building standards, electrical systems, building environment, fire prevention, theft prevention, accident prevention and damage prevention.
Architecture majors should first choose the location of the central computer room. From an economic point of view, we should avoid high-value gold areas; From a technical point of view, it should be as close as possible to the middle section of the system line and the comprehensive wiring well to facilitate the introduction of trunk lines such as city telephone network, cable TV network and optical fiber data network into the computer room; Considering the environment, it is required that the upper and lower sides should not be adjacent to potentially harmful rooms such as toilets and gas rooms, and the height of the floor and ceiling, as well as the shape, orientation, natural ventilation and lighting conditions and size should be considered. The position that should be paid attention to; In addition, the relative positions of central computer room and telephone room, fire control room and TV editing room should also be considered. Although there are many factors, only a few are hard. For example, the ceiling height of Grade A intelligent building must be 2.7m, while Grade B and Grade C are 2.6m and 2.5m. However, the clear height of the central computer room and other integrated wiring rooms is not less than 2.7m, regardless of Grade A, B and C. On the whole, the second floor is generally the first choice for the location of the computer room, and the top floor or basement of the podium is the second choice. The reason is that when the central computer room is on the second floor, it can be on duty jointly with the fire control room on the first floor (connected by an internal escalator), the top floor of the podium is close to the antenna, and the cable laying is relatively centered. The basement is generally near the equipment room of the main building.
Structural specialty should pay attention to the position, weight, size and shape of UPS battery, determine its ground bearing capacity (about 800KG/M2), leave holes and configure lintels. In addition to the mechanical structure, the structural specialty should also form a "faraday cage" in the computer room, so that the computer room can maintain equipotential and eliminate the step voltage when it is struck by various lightning, thus achieving the purpose of protecting the safety of people and machines.
It should be noted that the design standards and construction standards of HVAC are higher than those of ordinary offices, which are related to various parameters of the computer room environment, such as appropriate temperature, humidity, oxygen content, carbon dioxide content, dust content (cleanliness) and so on.
Design of computer room environment in comprehensive wiring engineering
The environmental requirements of the computer room are naturally higher than those of the general office. When it works normally, it needs not only enough light, but also suitable temperature, humidity, oxygen content, carbon dioxide content, dust content (cleanliness) and so on. One of the manifestations that its environmental monitoring is higher than that of ordinary offices is the different construction standards. The national standards for computer rooms are divided into Grade A and Grade B. ..
Different from the traditional comfort air conditioner, the precision air conditioning used in the computer room strictly controls the evaporation pressure in the evaporator, and increases the air supply volume to make the surface temperature of the evaporator higher than the dew point temperature of the air, so there is no need for dehumidification, and all the generated cold energy is used for cooling, which reduces the water loss and improves the economic benefits. Because of the large air supply volume, on the one hand, the enthalpy difference of air supply is small, on the other hand, the air exchange times in the machine room are many, which makes the whole machine room form an overall air circulation and the equipment in the machine room can be cooled in a balanced way. While the air circulation is good, precision air conditioning has a special air filter to filter out the dust in the air in time and effectively, so that the cleanliness of the computer room can meet the requirements.
Precision air conditioning system in computer room is generally equipped with humidification system, special high-efficiency dehumidification system and electric heating compensation system. The data sent by the sensor can be processed by the microprocessor, which can accurately control the temperature and humidity of the computer room. However, the general air conditioning system has no humidification system, and can only control the temperature, which has low accuracy and cannot meet the needs of the computer room. In addition, due to the good sealing of the machine room, many heating devices, continuous operation and high reliability requirements, the general air conditioning system is difficult to be competent, especially in winter, because the outdoor condensation pressure is too low, the general air conditioning system is difficult to work normally, and the precision air conditioning system can ensure the normal work of the refrigeration cycle through the controllable outdoor condenser.
Lighting and fire protection design of computer room in comprehensive wiring project
Electrical specialty should pay attention to lighting design, location, quantity and monitoring requirements of power equipment, and comprehensive grounding lead connection. The power load of the central computer room is Grade I, and a dedicated two-way terminal power supply circuit should be adopted. The wire is fire-resistant or flame-retardant copper core wire, and the battery is a closed product. The selection margin of components and materials in the distribution system should be slightly larger to prevent electrical fire. When the computer room works normally, it not only needs high environmental monitoring, but also needs sufficient illumination. The illuminance standard of artificial lighting in the central computer room is 150-300LX, 400LX and 500-750LX.
Fire protection design includes smoke alarm and gas fire extinguishing. The main forms of smoke alarms are ceiling smoke detectors and cable smoke detectors. Generally, the protection radius of ceiling smoke sensor is not more than 5.8m, and the distance from wall, tuyere and beam is not less than 0.5m Cable smoke detector can be laid along the wall. The air duct that must pass through the machine room shall be provided with a fire damper at the wall (it will automatically close when the ambient temperature reaches 70°C). The function of gas fire extinguishing system is similar to that of ordinary office sprinkler system, and its design points include the selection of system type and structure, the determination of extinguishing agent concentration, gas injection time, extinguishing agent dosage and impregnation time. The main types of gas fire extinguishing systems are carbon dioxide fire extinguishing system and halon fire extinguishing system. CLAN's low-smoke halogen-free outer sheath can solve the secondary problem. In addition, indoor fire-fighting facilities such as AC and DC dual power emergency lights, fire accident broadcast, 1 19 dedicated line fire-fighting telephone, fire alarm button, etc. Attached. The decoration materials of the computer room shall meet the requirements of relevant fire protection codes.