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183
Chapter The internal lightning protection system
. Lightning and switching
operations generate large transient surges that can be
prevented with surge protection devices. They are the most
common cause surge voltages.1. The voltage exceeds the maximum permissible
nominal voltage, electronic devices are damaged and
installed surge protection devices cannot protect
against these long-lasting mains frequencies. Only surge
arrestors can safely arrest these dangerous voltages.
3.
3. These surge
voltages simulate surge currents (8/20
μs).2.1 Transient surges voltages
Transient surges are short-lived surge voltages lasting
for matter microseconds.TBS
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Example split Earth
System: 50%–50%
i kA; Ohm
U 50,000 Ohm 50,000 V
U Surge voltage
i Lightning surge current
R Earthing resistance
The voltage resistance the components ex-
ceeded and uncontrolled arcing occurs.2.2.g.1 Switching operations
(SEMP: Switching electromagnetic pulse)
Switching operations occur due the switching of
large inductive and capacitive loads, short circuits and
interruptions the power system.2.
U1 Between phase (L1) and neutral conductor (N)
U2 Between phase (L2) and neutral conductor (N)
U3 Between phase (L3) and neutral conductor (N)
U12 Between phase (L1) and phase (L2)
U23 Between phase (L2) and phase (L3)
U31 Between phase (L3) and phase (L1)
Effect break neutral wire: neutral point displace-
ment case asymmetry
3. The safety and installation standards IEC 60364
additionally stipulate that surge voltage protection
measures are required important protective
measure low-voltage systems.2.2. When
a person walks carpet, charge separation occurs
– this instance, harmless humans.
3.
3. For example, a
break neutral cable can generate impermiss-
ible increase voltage the three-phase power sys-
tem. Mains
frequency faults this kind can last for between sev-
eral seconds and several hours.3 Planning methods
Part the lightning protection standard IEC 62305
describes how protect electrical and electronic sys-
tems. Equipotential bonding necessary here avoid
this charge separation.2 Types surge voltages
Transient, temporary and permanent surge voltages
represent the three primary types surge voltages. However,
it can interfere with and destroy electronic compon-
ents. Sources include e.2 Static discharges
(ESD: Electrostatic discharge)
Electrostatic discharges are caused friction.2.1.2.
3.2 Temporary and permanent surge voltages
Temporary, transient, surge voltages occur due to
faults the mains power supply. motors, ballasts and industri-
al loads
