Tuesday, June 23, 2015

Electromagnetic interference shielding data center cabling system

1, interfering with the data center cabling system

Cabling system consists of several subsystems, signal size of each subsystem used, frequency, etc. are not the same height, so there is interference, as well as the mutual interference between the various loads. To sum up, the integrated wiring system has the following sources of interference.

1.1 sources of interference from the data center within the building

(1) distribution network and the distribution box to generate high-frequency interference.

(2) high-power electric motor electric spark generated by harmonic interference.

(3) fluorescent lamps, electronic ballasts produce interference.

(4) High-frequency switching power supply interference.

(5) generated by the telephone ringing current interference.

(6) Information processing device generates periodic pulse interference.

If the cabling system can not keep a safe distance from these sources may be used to reduce or eliminate shielding system interference sources above the interference of cabling system.

1.2 the source of interference from outside the data center building

Sources of interference from outside the data center architecture are:

Radar, radio transmission equipment, mobile phone base stations, high-voltage wire, electrified railways, lightning strike zones in the interference signal environment and so on.

Obviously intelligent building external interference sources have a high electric field strength, when external cabling systems exist one or more sources of interference should be shielded system.

1.3 sources of interference from the surrounding environment cabling system

Cabling system noise level ambient interference signal field strength or integrated wiring system also should be shielded to protect the system exceeds the following requirements.

(1) computer local area network, if the frequency of the interference signal is introduced l0kHz ~ 600MHz, its field strength of 1V / m; frequency of 600MHz ~ 2.8GHz interference signal field strength of 5V / m.

(2) telecommunications terminal equipment, is introduced through the signal line and other DC or AC frequency of the interfering signal introduced into 15 ~ 80MHz, the field strength of 3V / m (amplitude modulation 80%, 1kHz).

Terminal Equipment (3) with analog / digital terminal interface to provide telephone service, the noise level exceeds 40dB total bandwidth should be less than 200MHz.

(4) The background noise level should be at least 12dB smaller than the reference.

2, comprehensive sets of wiring system anti-jamming measures

Electric field strength interference waves emitted cabling system exceeds a predetermined value, whether factors that need protective measures is more complex, which is the most harmful anti-electromagnetic interference and electromagnetic radiation. EMI issues related to the cabling system can work properly; electromagnetic radiation is related to the safety of cabling system under normal operating conditions information from being stolen by other persons, or causing electromagnetic pollution.

Conducting integrated wiring systems engineering design must be in accordance with the requirements of the construction unit, carry out a detailed arrangement and design, selecting appropriate protective measures.

2.1 shielding measures to reduce electromagnetic interference

Metal casing (1) Information systems, cable shield and metal trunking and other buildings in the introduction frame or equipotential bonding. Information system lightning protection zone in which the magnetic field strength attenuation should be calculated, to take appropriate measures to shield according to the results.

(2) The data center should not be located in high-rise buildings, should lower center of the building. Related equipment to try to stay away from the building facade. Take appropriate measures in accordance with the requirements of lightning protection zones shield and information equipment, electromagnetic field generated when the lightning to the inner decay.

(3) The information device is a non-metallic housing and the shield of the building did not meet the requirements, the importance of information equipment room or equipment based on the direct installation of metal screen or shielded room, shielded metal shielded rooms and other potential connection with phase.

Outdoor line of shielding measures 2.2

Outdoor wiring shield to note the following.

(1) the need to protect the local potential should use shielded cables and both ends of the shielding layer is peer connections, the shield after the junction of the lightning protection zones should also be equipotential connection.

(2) the use of the cable metal-containing components, shall at all into the household of the metal plugs, metal tidal layer and the metal strengthening the core metal member equipotential connection.

Room (3) Building interconnecting cables should be laid in a metal pipe, metal pipe ends to be connected to other potential electrical connections and connections to bring each building. Cable conduits must be equipotential connection. If between adjacent buildings have power and communication cables, the grounding device should be connected to each other.

2.3 Strengthening internal cabling system structure and materials of immunity

This is mainly possible electromagnetic interference requirements for products and equipment may be affected by electromagnetic interference raised. Specific requirements in the manufacturing process is tested to the appropriate standard.

Overall, computer equipment, communications equipment and electronic equipment and other products shape the structure should be made of a metal material box, box, cabinet or shelf, making it in the form of a Faraday cage, a ground terminal, and well grounded. This ability to somehow enhance immunity and radiation protection equipment.

For cable selection Cabling system must meet the system requirements, combined with the buildings surrounding electromagnetic environment into account, usually anti-jamming capability and transmission capacity is the major consideration, but also to consider the economic cost.

Select cables and cabling system connecting hardware, when determining whether a category that you want to ensure consistency. If you choose to shield the cables and connecting hardware must be shielded, and have a good grounding system. Link cabling system commonly used twisted pair, UTP has the ability to absorb and emit electromagnetic waves.

2.4 Note from the equipment and transmission lines between the different sources of interference

In addition to the use of shielded cabling system, well grounded in order to improve their own immunity, radiation protection, but also as far away from interference sources, in order to reduce its impact on the normal operation of the system, improve the reliability of systems and equipment to make Data center cabling system truly become a standard, standard cabling system.

Through a number of experiments shows that when the interference source distance transmission line at different distances, the distortion degree of the transmission signal is different. Therefore, in the construction and installation process should pay attention to the relationship between the wiring system and the distance from the source of disturbance, in strict accordance with standard design, construction, and make the appropriate testing to ensure normal and reliable cabling system.

No comments:

Post a Comment