The area under the current-time curve for surge cur-
rents indicates the amount charge.) that are routed into the
building.
This rise potential poses threat the electrical
systems (e.
Example:
• Lightning current (i): 100 kA
• Earthing resistance (R): Ω
• Voltage drop (u):
R 100 100,000 V
Conclusion:
The voltage between the earthing resistance and the
remotely earthed network increases 100 kV. Type lightning current arresters
and external lightning protection components are
tested using this pulse. Surge arresters type and
type are impacted with this test impulse.g.
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21
Chapter General introduction
. The energy content this impulse signific-
antly lower than the lightning test current surge cur-
rent wave 10/350 μs. The charge of
the lightning test current waveform 10/350 roughly
corresponds times the charge surge current
of waveform 8/20 with the same amplitude. Suitable test currents for testing different
lightning and surge protectors have been defined in
national and international standards.
Direct lightning strike: Pulse shape 1
Lightning currents that can occur during direct light-
ning strike can imitated with the surge current of
waveform 10/350 μs. voltage supply, telephone systems,
cable TV, control cables, etc.4 Test currents and simulated
surge voltages
High lightning currents can flow the ground during
a storm. building with external lightning protection
receives direct hit, voltage drop occurs the
earthing resistance the lightning protection equipo-
tential bonding system, which represents surge
voltage against the distant environment.TBS
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Pulse shape Direct lightning strike, 10/350 simu-
lated lightning pulse
Pulse shape Remote lightning strike switching op-
eration, 8/20 simulated current pulse (surge voltage)
Types pulse and their characteristics
1.
Remote lightning strikes switching operations:
Pulse shape 2
The surges created remote lightning strikes and
switching operations are imitated with test impulse
8/20 μs. The lightning test current imit-
ates both the fast rise and the high energy content of
natural lightning
