n High frequency interference in the power supply network is generated when the primary coil of the power supply transformer is coupled to the secondary coil through distributed capacitors. To suppress such interference, we can use an appropriate transformer, and install a low-pass filter at the inlet of the power supply cable.
n The interference of the transient voltage in the power supply network can be reduced by inputting power directly from the primary transformer with a filter capacitor for the optical synchronous transmission equipment.
n When the optical synchronous transmission equipment works in the 50Hz mains power supply network with the above interference, the surge voltage caused by the power supply network and the over-voltage generated by lightening will be passed to the power supply of the optical synchronous transmission equipment, which leads to computing errors of the processors. Therefore, before directly using the mains supply, effective measures against interference from power supply network should be taken.
n The key to eliminate the interference from the grounding system is to avoid loops among various grounds, such as the signal ground (including analog and digital grounds), BGND, PGND and shield ground, or loops formed by large distributed capacitors. Otherwise, the common impedance interference from the grounding system may affect the operation of the equipment. In buildings other than high-rises, the working ground of the optical transmission equipment should be separated as far as possible from the ground for electricity equipment and lightning protection device.
n Prevent electromagnetic radiation interference from the surroundings to the equipment. In some integrated communication buildings, if there is a high frequency transmitter there, its influence on the optical transmission equipment should meet the relevant requirements. Independent power supplies are recommended for them.
n EMI from the telecommunications line should be restrained. Influenced by high frequency electromagnetic field (external interference), high longitudinal voltage will occur to the core and sheath of the communication cable. Because of the asymmetry of cores in the cables, the longitudinal voltage will generate a horizontal noise voltage at the ends of the cores. When both ends of the cable sheath are grounded, the sheath will function as a shielding layer, greatly reducing the longitudinal voltage and reducing the interference voltage. Other effective methods include: reduce the voltage or current of the interference source; reduce the line length and the spacing of the conducting wires to reduce the area of the affected loop; directly place the insulated conducting wires on the grounded floor; use a special grounding feedback cable to avoid co-impedance; or twist the signal cable and the feedback cable together to offset partial peripheral electromagnetic interference, etc.
3. Fire protection
For small equipment rooms, a certain number of portable fire extinguishers should be equipped in each room for an initial fire control. In large equipment rooms, fire extinguishing facilities should be equipped. An automatic fire alarm system should also be equipped in the equipment room. All telecom buildings with fire alarm system should have fire emergency lighting system and evacuation instruction marks at important places, paths and gateways.
4. Anti-earthquake demand
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