Four lines of lightning protection:

1, shielding (blocking): lightning rod, lightning rod, use cable and other measures, not around the strike not directly hit the wire;

2. Insulator non-flashover (blocking): strengthen insulation, improve grounding and other measures to make the lightning avoider;

3. Flash burning transfer (thinning): Even if the insulator flashover, it should not be transformed into a steady power frequency arc as far as possible, so as to improve the reliability of arc extinguishing, change the arc path, transfer the failure point, and no switch trip. For this reason, the power frequency electric field strength of the insulator should be reduced or the neutral point of the electric network should be ungrounded or pass through the arc suppression ring. This allows most single-phase ground faults caused by lightning strikes to be eliminated automatically without causing interphase short circuits and trips.

4, no power outage: This is the last line of defense, even if the switch trip will not interrupt the power supply. To this end, it can adopt automatic reclosing or double circuit, ring network power supply and other measures.