Lightning protection zones concept
Definition of Lightning Protection Zones (LPZ) (excerpt from IEC 62305-4)
| LEMP protection of structures with electrical and electronic systems in accordance with IEC 62305-4 | |
| Zone | Description |
| LPZ 0A | Zone where the threat is due to the direct lightning flash and the full lightning electromagnetic field. The internal systems may be subjected to full lightning surge current. |
| LPZ 0B | Zone protected against direct lightning flashes but where the 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 | 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. |
Safety according to specification
Failures of technical systems and installations are very unpleasant for the operators. They require faultless operation from the equipment both under “normal“ conditions and during thunderstorms. Loss reports of insurance companies show clearly that there is a backlog demand both in the private (Fig. 1) and the commercial sector (Fig. 2). A comprehensive protection concept would help to achieve this aim. The Lightning Protection Zones Concept enables designers, constructors and operators to plan, perform and control protection measures. Thus, all relevant devices, installations and systems are protected reliably and furthermore with economically acceptable efforts.
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| Fig. 1: Causes of damage to electronic equipment for 2001. Analysis of 7370 damage claims (Ref.: Württembergische Versicherung AG) |
Fig. 2: Average damage causes in the last years (Ref..: Gesamtverband der Deutschen Versicherungswirtschaft e.V., Berlin 2001) |
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15,3%
Others
22,9%
Negligence
5,6%
Water
4,6%
Fire
27,1%
Theft, Vandalism 
23,7% Surges
0,8%
Elemental
Protection philosophy
To ensure continuous availability of complex electrical and IT systems, even in case of a direct lightning effect, further measures for surge protection of electrical and electronic installations are necessary, based on a building lightning protection system. Taking all causes of surges into consideration is very important. For this purpose, the Lightning Protection Zones Concept described in IEC 62305-4 is applied. Here, a structure is subdivided in different risk zones. These zones help to define the necessary devices and components for lightning and surge protection. Part of an EMC-conform lightning protection zones concept is an external lightning protection system (including air-termination system, down conductor system, earthing system), equipotential bonding, spatial shielding and surge protection for the power supply and IT systems.
Click into the picture for enlargement
The definition of the lightning protection zones is subject to the predeterminations of Table 1. ln correspondence with the requirements and loads on surge protective devices regarding their installation site, these are classified as lightning current arresters, surge arresters and combined lightning current and surge arresters. The highest requirements on discharge capacity are made on lightning current and combined lightning current and surge arresters, which realise the transition from Lightning Protection Zone 0A to 1 or 0A to 2. These SPDs must be able to conduct partial lightning currents, wave form 10/350 µs several times without destruction in order to prevent the entering of destructive partial lightning currents into the electrical installation of a building. At the boundary from LPZ 0B to 1 or downstream of the lightning current arrester at the boundary from LPZ 1 to 2 and higher, surge arresters are used for protection against surges. Their function is to further reduce both the residual load of the upstream protection stages and limit the inducted or own surges. The aforementioned lightning and surge protective measures at the boundaries of the lightning protection zones apply to both the power supply and IT system to the same extent. Due to the entirety of the measures described in the EMC-conform Lightning Protection Zones Concept, a permanent system availability of a modern infrastructure can be achieved.
 Brochure
"DEHN stops surges" PDF [2.2 MB] DS 614 |