Siemens SIMATIC ET 200AL, System Manual

Page: 2247 / 2255

Lightning protection and overvoltage protection
7.3 Rules and components for the transitions between lightning protection zones
Designing interference-free controllers
Function Manual, 06/2014, A5E03461486-AB
29
7.3 Rules and components for the transitions between lightning
protection zones
Introduction
This chapter provides you with information on the rules for transitions between lightning
protection zones. Measures must be taken to reduce the surge current load and the
magnetic fields at the transitions between the lightning protection zones.
Each zone-penetrating metallic/electrical system is incorporated into the equipotential
bonding at the zone transition.
The metallic systems include channels, structural parts, and pipes (for water, gas, and heat,
for example).
Electrical systems include power and IT cables and wires (for example, power cables and
bus cables).
Transitions between lightning protection zones
Overvoltage protection must be provided at the transitions between lightning protection
zones (LPZ - Lightning Protection Zone) in accordance with DIN EN 62305. The protection
levels are defined at the transitions and implemented by means of overvoltage protection
devices (SPD - Surge Protective Device).
●
SPD Type 1 - Coarse protection for the transition from LPZ 0 to LPZ 1
● SPD Type 2 - Medium protection for the transition from LPZ 1 to LPZ 2
● SPD Type 3 - Fine protection for the transition from LPZ 2 to LPZ 3
The following figure illustrates the lightning protection zones and the type classes from the
supply line to the consumer.
Figure 7-2 Lightning protection zone transitions