The different lightning protection classes, also known as Lightning Protection Levels (LPL), only refer to the type I arrester and its impulse current 10/350 µs. A distinction is made between lightning protection classes I, II and III/IV, with the probability of lightning damage increasing from lightning protection class I to lightning protection class III/IV.
Lightning impulse current [Iimp]: 200 kA
Effectiveness: 98%
Lightning impulse current [Iimp]: 150 kA
Effectiveness: 95%
Lightning impulse current [Iimp]: 100 kA
Effectiveness: 88% / 81%
A pulse of 200 kA hits the external lightning protection system directly and is conducted half into the earth and half into the electrically conductive parts of the system. Depending on the number of conductors, the current is divided into 25 kA (4-conductor system) or 20 kA (5-conductor system) per conductor.
Examples of lightning protection class I are:
A pulse of 150 kA hits the external lightning protection system directly and is conducted half into the earth and half into the electrically conductive parts of the system. Depending on the number of conductors, the current is divided into 19 kA (4-conductor system) or 15 kA (5-conductor system) per conductor.
Examples of lightning protection class II are:
A pulse of 100 kA hits the external lightning protection system directly and is conducted half into the earth and half into the electrically conductive parts of the system. A current of 12.5 kA per conductor is assumed for both a 4-wire system and a 5-wire system.
Lightning protection class III/IV covers approx. 80% of all applications, e.g:
This example shows how to select the correct type I arrester.
Assumption:
It is an application with external lightning protection.
Calculation:
Parameters for lightning and surge protection:
Product recommendation:
The publication ‘Risikoorientierter Blitz- und Überspannungsschutz ’ from the German Insurance Association (GDV) offers help in assessing the risk of damage caused by lightning and surges.
The document describes various objects and their assignment to the lightning protection classes. Normally, a complex calculation is required to determine this classification. The document helps for a quick classification, is only valid in Germany and is only a recommendation, but does not release from a risk assessment.
