Matters needing attention in design of weak current room

Safety measures for the central computer room include the prevention of illegal intrusion into the network, lightning protection, grounding, fire prevention, power cut-off, anti-static and other content, which are essential to ensure the safe operation of equipment.

1. UPS power supply system planning

The useful work of building an intelligent system depends on normal power supply, especially in the computer room, which is the head of the intelligent building. As we all know, when a computer is working, it will lose data if it is cut off. So the power system of the computer room is very important. As for the general distribution system of intelligent building, it is allowed to have normal power cut or power cut at the incident end, but it is not allowed for the central computer room. The general treatment method is divided into two parts, one is in front of the alternating current power supply to attract two lines of electricity, when conditions can be added to the generator, become a multi-channel power supply, improve the reliability of power supply; the other is in the room with uninterrupted power UPS, with a certain DC battery pack as a backup power, to ensure power supply. The former is the traditional method of improving the reliability of power supply, while the latter is more and more widely used in recent years with the rapid development of information technology. Two existing UPS power supply options are available. One is on-line, that is, UPS has been in power supply status, all the time in operation, UPS replaced the city power supply for computer network equipment power. The second is backup, that is, the computer network equipment usually rely on the power supply of the city, only when the city power outage immediately by UPS power supply. Backup power supply has a zero-crossing problem, that is, when the city power failure, no matter what kind of closing method, can not avoid the instantaneous no-power problem. City power is 50HZ, leap II PC is more than 500MHZ, obviously, in the moment of power failure, the computer may lose data. The specific method is divided and conquered: if the system is normal blackout, must have told in advance, can be put into UPS; if the fault (short circuit, grounding) blackout, because the inductance current can not jump, capacitor voltage can not jump, can be set to the active access of UPS less than the tripping current value, that is, before the circuit is disconnected, UPS has been connected.

UPS power supply is developing in the direction of high power, low noise, intelligence and network, which is exactly what the central computer room needs. High-power UPS power supply (such as 20, 30, 60KVA and above) mostly has parallel redundancy function. The new hot-plug and modular battery array further improves the reliability of power supply. This is because "array structures" have proven to be advantageous to improved reliability when previously used as "disk arrays" for computer networks.

Two, the use of anti-static floor.

Antistatic means to eliminate static charges all over the machine room in time. Friction electricity generation is a natural phenomenon. The accumulation of static electricity will cause accidents and damage electronic equipment and personal safety. Therefore, the machine room should use anti-static floor, after grounding discharge static charge. The floor is usually built from 0.3m. In order to ensure the quality of the construction, the engineering of the computer room should be borne by the units with the qualification of the construction of the computer room.

Three. Lightning protection grounding plan for computer room

A large number of electronic equipments in the central computer room have lower operating voltage and more fine equipments, which make it difficult to withstand lightning strikes. Once they are subjected to lightning strikes, they often lose a lot. Therefore, it has a higher level of lightning protection and a higher demand for various lightning protection measures. There are many kinds of lightning methods, and lightning protection methods mainly aim at direct lightning and inductive thunder. The common method is to install lightning rods and lightning bands on the roof to prevent direct lightning strike; interconnect the main bars of the whole structure in the building to form an equipotential Faraday cage and a pressure equalizing ring to prevent side lightning strike. Body interconnection constitutes an excellent grounding and ground potential dispersion in the building. In addition, the exterior metal equipment and household metal pipes will be connected with the grounding grid to ensure that the building's equipotential.

In order to avoid the high voltage lightning wave invading the equipment in the computer room, a variety of anti-overvoltage equipment can be selected at the front end of the equipment in the computer room. For example, three-stage lightning protection and maintenance equipment in front of network equipment can be used to distribute and limit voltage to avoid the invasion of induced lightning waves. In addition, antenna feeders, signal lines, data communication lines and so on should be installed at the entrance to the house.

The grounding system includes lightning protection grounding, AC operation grounding, DC grounding, PE maintenance grounding, shielding grounding and anti-static grounding, the latter three can be interconnected. The grounding method generally uses the combined grounding method, that is, lightning protection grounding, maintenance grounding, operation grounding and so on are directly connected with the grounding grid, the total grounding resistance should be less than 1 ohm, that is, the so-called zero grounding resistance. Special earthing equipment can also be set up when conditions permit.

In digital circuits, the logical grounding for the equipotential plane and the signal grounding for the reference potential in the analog circuit become DC grounding. The reference potential of DC grounding system is derived from the total equipotential copper bar. The insulation copper core wire with a cross section of 35 square millimeters can be selected to lead through the maintenance pipe to the weak current equipment for DC grounding.

Shielding grounding and anti-static earthing are to deal with electromagnetic radiation and electromagnetic disturbance. With the increasing number of high frequency communication equipment in intelligent building, anti disturbance is becoming more and more important. Electromagnetic disturbance (EMI) is the parasitic electric energy radiated by electronic system. It can reduce the accuracy of data transmission, add bit error rate, affect the clarity, and form electromagnetic environmental pollution. In order to avoid external electromagnetic disturbance, the shield wire in the electronic equipment shell and the equipment table may be grounded through the wire metal pipe. The whole shield is called shield grounding. In general, the environment in the computer room is relatively dry, and static electricity occurs simply, which disturbs the electronic equipment. Therefore, the ground is chosen to prevent static electricity grounding. The general method of shielding grounding and anti-static grounding is that the PE weak electric trunk line is drawn out from the total equipotential copper row in the building, each floor is equipped with weak equipotential copper row, the shell of electronic equipment, metal pipeline and anti-static grounding are connected with the equipotential copper row.

In addition to the above measures, the computer room security equipment should also have access control, theft-proof, CCTV monitoring, firewall software, fire alarm and so on.

Four, computer room planning standards

The planning stage of the central computer room can be divided into start planning, civil engineering planning, resettlement and decoration deepening planning, planning review and completion plan. At the beginning of the plan, the composition, primary functions and microscopic requirements of the engine room should be determined. The civil engineering plan determines the orientation, area, shape and level. Deepening the planning to determine the plane and elevation of the computer room, decoration practices, mechanical and electrical equipment selection, lighting and so on. The planning of the central computer room is mainly in accordance with the GB50174-93 "Computer Room Planning Standards" and other standards. The primary contents touched on are construction standards, electrical systems, construction environment, fire prevention, burglar prevention and end-to-end damage prevention. To build a specialty, we must first select the location of the central computer room. From the economic point of view to avoid the high value of the golden area; from the technical point of view to close to the middle of the system line, but also as close as possible to the weak shaft, so as to facilitate the introduction of the city telephone network, cable television network and fiber optic data network trunk line into the computer room; from the environmental point of view, it is required that the upper and lower sides of the toilet, gas room and so on have no potential. In the damaged room adjacent, should consider the height of the floor and ceiling height, pay attention to the location of the shape, orientation, natural ventilation and lighting conditions, size, etc. In addition, the center room and telephone room, fire control room and television editing room should also take into account the relative position. Although these factors are many, only a small amount of them are hard, such as the ceiling height of Class A intelligent building should be guaranteed to be 2.7m, Class B and Class C to be 2.6m and 2.5m, but the net height of the central computer room and other weak motor room should be no less than 2.7m, not divided into Class A, Class B and Class C. From the perspective of induction, the orientation of the engine room is generally preferred to the two level, the second choice is the skirt roof or the underground one. The reason is that the central computer room can be jointly on duty with the fire control room on the second floor (connected to the inner ladder), the top floor of the podium is close to the antennas, and the cable is in the middle. The ground floor is generally close to the main building.

Structural specialty should pay attention to the orientation, weight, size and shape of UPS batteries, determine the bearing capacity of the ground (about 800KG / M2) and leave holes and configuration of beams. In addition to the mechanical structure, the structural specialty should form a "Faraday cage" in the computer room, so that the computer room under various lightning strikes including induction lightning opportunity room insist on equipotential, eliminate step voltage, to achieve the purpose of safeguarding human and machine safety.

The equipment specialty should pay attention to heating, ventilation, air conditioning planning standards, construction standards higher than the general studio, with the relevant room environment parameters, such as appropriate temperature, humidity, oxygen content, carbon dioxide content, dust content (cleanliness) and so on.
Five, computer room environment planning

The environment requirement of the computer room is naturally higher than that of the general studio. It needs not only the illumination but also the suitable temperature, humidity, oxygen content, carbon dioxide content and dust content (cleanliness) in normal operation. One of the embodiment of environmental monitoring is higher than that of general studio. The national standard of machine room is divided into A and B.

Different from the traditional comfortable air conditioning, the precise air conditioning selected in the computer room strictly controls the evaporation pressure in the evaporator, increases the air supply so that the evaporator surface temperature is higher than the air dew point temperature, so no dehumidification is needed, and all the cooling occurring is used to cool down, thus reducing the loss of moisture and improving the economic benefits. Because of the large air supply, on the one hand, the difference between the enthalpy of air supply is small, on the other hand, the number of ventilation in the machine room makes the whole air circulation in the machine room, and the equipment in the machine room can be cooled equally. Excellent in the air cycle together, because fine air conditioning with special air filters can be timely and useful to filter out the dust in the air, so that room cleanliness to meet the requirements.

The fine air-conditioning system in the computer room is generally equipped with humidification system, special high-efficiency dehumidification system and electric heating compensation system. The temperature and humidity of the computer room can be accurately controlled by processing the data sent by the sensor by the microprocessor. However, the general air-conditioning system has no humidification system and can only control the temperature, and the accuracy is low, which can not meet the requirements of the computer room. Demand. Otherwise, because the machine room is well sealed and there are many heating equipment, continuous operation, year-round operation, high reliability requirements, the general air conditioning system is not competent, especially in winter, because the general air conditioning condensation pressure is too low, difficult to operate normally, and fine air conditioning system through controllable outdoor condenser, can ensure refrigeration cycle Normal operation.

Six, computer room lighting and fire planning

Electrical professionals should pay attention to lighting planning, power equipment orientation, number of stations and monitoring requirements, as well as inductive grounding lead connection. The electrical load of the central computer room is classified into one grade. The special double terminal mutual switching power supply circuit should be selected. The wire is fire-resistant or flame-retardant copper core wire, and the battery is closed product. The allowance for equipment and data in distribution system should be slightly larger so as to prevent electric fires. During normal operation, the computer room not only has high environmental monitoring, but also needs illumination. The artificial daylighting standard of the central computer room is 150-300 LX with low light intensity, 400 LX with medium light intensity and 500-750 LX with high light intensity.

Fire planning includes smoke alarm and gas saving two parts. Smoke alarm is based on smoke absorption device with ceiling type and cable type. The maintenance radius of the ceiling type smoke detector is generally less than 5.8m, and the distance from the wall, the air outlet and the girder is not less than 0.5m. The cable type smoke sensor can be laid along the wall. It is necessary to install a fire-proof valve at the crossing wall of the air duct passing through the engine room (when the ambient temperature reaches 70 degrees C, the air duct closes actively). The function of the gas rescue system is similar to that of the spray system in the general studio. The key points of its planning are the selection of the system type and structure, the determination of the concentration of the rescue agent, the time of gas spray, the dosage of the rescue agent and the time of impregnation. The most important species of the gas rescue system are carbon dioxide rescue system and halogenated alkane rescue system. In addition, the room is equipped with AC and DC dual power emergency lights, fire broadcasting, 119 dedicated line fire telephone, fire alarm button and other fire fighting equipment. The decoration information of the engine room should conform to the requirements of the relevant fire protection standards.