Lightning protection and overvoltage protection
7.2 Lightning protection zone concept
Designing interference-free controllers
28
Function Manual, 06/2014, A5E03461486-AB
Division of lightning protection zones
The various lightning protection zones (LPZ - Lightning Protection Zone) are limited spatially
as follows and not necessarily by physical boundaries, such as walls or floors.
The following table explains the division into various lightning protection zones.
Table 7- 1
External and internal lightning protection zones
Lightning protection zones
External lightning protection zones:
LPZ 0
A
•
Risk from direct lightning strikes
•
Risk from the full electromagnetic field of the lightning
LPZ 0
B
•
Protected against direct lightning strike
•
Risk from the full electromagnetic field of the lightning
Internal lightning protection zones:
LPZ 1
•
Protected against direct lightning strike
•
Attenuated electromagnetic field of the lightning
LPZ 2
•
Protected against direct lightning strike
•
Reduced leakage currents and electromagnetic fields compared to LPZ 1
•
Protected terminal devices
LPZ 3
•
Protected against direct lightning strike
•
Protected area inside the terminal device
•
Local equipotential bonding
Effects of the lightning strike
Direct lightning strikes occur in the lightning protection zone LPZ 0
A
. Effects of the lightning
strike are high-energy lightning currents and strong electromagnetic fields. These effects are
reduced from one lightning protection zone to the next through suitable lightning current or
overvoltage arrester/shielding measures.
Frequent damage caused by lightning strikes includes:
●
Injury to people and animals, which may in worst cases lead to death
●
Damage to buildings
●
Fire caused by strong heat development of a lightning strike
Overvoltages
Electromagnetic fields of the lightning channel can be reduced with appropriate shielding
measures. Overvoltages due to inductions can be reduced to a safe level starting in lightning
protection zone LPZ 0
B
with overvoltage arresters.
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