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Lightning protection safety technology

Lightning protection safety technology
1) Insulated conductor must be used for the protection zero line. The PE wire connecting the power distribution device and the electric machinery shall be insulated multi strand copper wire with a cross section of not less than 2.5mlif. The PE wire of hand-held electric tools shall be insulated multi strand copper wire with a cross section of not less than 1.5m jade.
2) It is forbidden to install switches or fuses on the PE line, to pass the working current, and to break the line.
3) The color marking of phase line, N line and PE line must comply with the following regulations: the insulation colors of phase sequence of phase lines LL (a), L2 (b) and L3 (c) are yellow, green and red in sequence; The insulation color of n-wire is light blue; The insulation color of PE wire is green / yellow. Under no circumstances shall the above color marks be mixed or substituted for each other.
4) When the construction site and external power lines share the same power supply system, the grounding and neutral protection of electrical equipment shall be consistent with the original system. It is not allowed to make protective neutral connection for some equipment and protective grounding for others.
5) When TN system is used for protective zero connection, the working zero line (N line) must pass through the general leakage protector, and the protective zero line (PE line) must be led out from the repeated grounding of the incoming zero line of the power supply or the zero line of the power supply side of the general leakage protector to form a partial TN-S zero connection protection system (Fig. 2).
6) In TN zero connection protection system, no electrical connection shall be made between the working zero line and the protection zero line through the general leakage protector.
7) In TN neutral protection system, PE neutral line shall be laid separately. The repeated grounding wire must be connected with the PE wire, and it is forbidden to connect with the N wire.
8) When the primary side is powered by a neutral protection system with a voltage of more than 50V and the secondary side is a safety isolation transformer with a voltage of less than 50V, the secondary side shall not be grounded, and the secondary line shall be protected with insulating tubes or rubber sheathed flexible wires. When an ordinary isolation transformer is used, one end of the secondary side shall be grounded, and the exposed conductive part of the transformer that is normally uncharged shall be connected to the protection zero line of the primary circuit. Protective measures against direct contact with live bodies shall be taken for the above transformers.