Hunan Heou Engineering Consulting Co., Ltd
Hunan Heou Engineering Consulting Co., Ltd
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Third level of protection
The purpose is the ultimate means of protecting equipment, the value of the residual surge voltage is reduced to within 1000V, so that the energy of the surge does not damage the equipment.
In the electronic information equipment AC power inlet end of the power supply lightning protector installed as the third level of protection should be series-limited power supply lightning protector, the lightning through-current capacity should not be less than 10KA.
The last line of protection can be used in the internal power supply part of the power equipment with a built-in power supply lightning arrester, in order to completely eliminate the purpose of the small transient overvoltage. The power supply lightning arrester used there requires a maximum impact capacity of 20KA per phase or less, and the required limiting voltage should be less than 1000V. For some particularly important or sensitive electronic equipment with the third level of protection is necessary, but also to protect power-using equipment from the transient overvoltage generated within the system.
For microwave communication equipment, mobile station communication equipment and radar equipment, such as the use of rectifier power supply, depending on its working voltage protection needs are appropriate to choose the working voltage of the appropriate DC power lightning arrester as the last level of protection.
Fourth level and above
According to the voltage level of the protected equipment, if two levels of lightning protection can be done to limit the voltage below the level of the equipment, only two levels of protection are required, if the level of voltage resistance of the equipment is low, it may require four or more levels of protection. The fourth level of protection should have a lightning through-current capacity of not less than 5KA.[3]
Installation Method Editor Podcast
SPD conventional installation requirements
Surge protector using 35MM standard rail installation, for fixed SPD, conventional installation should follow the following steps [1
1) Determine the discharge current path
(2) mark the additional voltage drop caused by the wire at the end of the equipment,.
3) To avoid unnecessary induction loops, the PE conductor of each device should be marked.
4) to establish an equipotential connection between the equipment and the SPD.
5) To carry out energy coordination of multi-level SPD
In order to limit the inductive coupling between the protected part of the installation and the unprotected part of the equipment, certain measurements need to be made. Through the separation of the induction source and sacrificial circuit, the selection of the circuit angle and the limitation of the closed circuit area can reduce mutual inductance, when the current-carrying component conductor is part of the closed circuit, due to the proximity of this conductor to the circuit and the induced voltage and reduce.
In general, it is better to separate the protected conductor from the unprotected conductor, and, moreover, should be separated from the ground wire. Also, in order to avoid transient quadrature coupling between the power cable and the communication cable, the necessary measurements should be made.
SPD grounding wire diameter selection
Data line: requires greater than 2.5mm²; when the length exceeds 0.5m requires greater than 4mm². yd/t5098-1998.
Power line: phase line cross-sectional area S ≤ 16mm², ground with S; phase line cross-sectional area 16mm2 ≤ S ≤ 35mm², ground with 16mm²; phase line cross-sectional area S ≥ 35mm², the ground requires S/2; GB 50057 section 2.2.9 [3]