Lightning Protection Zones

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Definition of lightning protection zones 

LPZ 0A Zone where the threat is due to the direct lightning flash and A the full lightning electromagnetic field. The internal systems may be subjected to full or partial lightning surge currents.

LPZ 0B Zone protected against direct lightning flashes but where the B threat is the full lightning electromagnetic field. The internal systems may be subjected to partial lightning surge currents.

LPZ 1   Zone where the surge current is limited by current sharing and by SPDs at the boundary.Spatial shielding may attenuate the lightning electromagnetic field.

LPZ 2...n Zone where the surge current may be further limited by current sharing and by additional SPDs at the boundary.Additional spatial shielding may be used to further attenuate the lightning electromagnetic field.

Lightning protection zones

Lightning protection zones concept based on EMC including the following parts(Figure.7 & 8):

* External lightning protection(air-termination system, down-conductor system, earthing);

* Lightning equipotential bonding;

* Space shield;

* Surge protection for power supply system and IT system.

                                 Figure 7 Lightning Protection Common Sense


                                                 Lightning Protection Zones

Air-termination systems (Rolling sphere)

The rolling sphere method: supposed a sphere with radius R, L,rolling along the protected object,the sphere touches the airterminationdevice and the ground at spot A and B, the sphereun-touched area ABC is the protected area by this air-termination device(Figure.9 & 11).The rolling sphere radius defined as below (according to IEC 61643-1):

Lightning protection ClASS/LEVEL

Radius  R(m)

Class/Level I   building/structure


Class/Level II  building/structure


Class/Level III building/structure


Class/Level IV building/structure


                          Figure 9.Rolling Sphere of  Air-Termination System 


                                Figure 10. Protective angle method for air/lightning rod


         Figure 11. Surge Protection Devices for interconnected Lightning Protection Zones