2 Insulated external lightning protection sys-
tem with insulators
An insulator should keep conductors routing lightning
current distance from metallic structures and elec-
trical systems, provide insulation against the induced
voltage case lightning strike and resist the en-
vironmental loads, such ultraviolet radiation and
soiling, and the tension and pressure forces resulting
from snow, ice and wind. The separation distance defined DIN
EN 62305-3 (IEC 62305-3) and contains the coeffi-
cient km.13.2. Instead km, the manufacturer states the ef-
fective length correction factor kx, which confirmed
in type test. However, insulators are a
part mechanically coupled system made in-
sulating materials and ladders. specifies the ratio the standing
lightning pulse voltages air spark gap and in-
sulator aged radiation.TBS
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2.
lst Thread measure the insulator
Further type tests are described IEC 62561-8
and contain the following points:
• Documentation
• Labelling
• Construction
• Ultraviolet light
• Corrosion
• Extraction force
• Bend test
• Impact test
• Electrical testing
The following applies for the calcu-
lation the separation distance
according IEC/EN 62305-3:
km
= kx.
The most important requirement the compliance of
the necessary separation distance, even the insulat-
or moved.
kx leff/lst Effective length correction factor
leff Strike distance air spark gap with equivalent
discharge behaviour insulator.
Stand
Insulator
Metal bracket
Air-termination system/conductor
Insulated holder
lst
Thread measure the insulator
Definition thread measure the insulator
TBS
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131
Chapter The external lightning protection system
