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Surge protection concept
Surge protection concept
Fundamental concept of protection
One important aspect of surge protection is the area of
power supply and distribution. The procedure is linked to the
systematic subdivision prescribed by the protective zones
concept and the corresponding coordination of surge
arresters. Protection of power supply lines forms the basis
for protecting all electrical and electronic equipment right
down to the smallest and most sensitive components.
A fundamental requirement for effective surge protection is
the presence of properly functioning equipotential bonding
to DIN VDE 0100 part 540 in a series, or better still, star or
grid arrangement.
DIN VDE 0110 (insulation coordination) divides overvoltage
protection for power supplies and power distribution into the
following three areas:
1. Power supply
The surge voltage strength of the insulation is 6 kV
from the incoming supply to the building – by means of
underground cables or overhead lines – right up to the
main distribution board (backup fuse and meter cupboard).
Owing to the lightning protection zoning concept and the
physical circumstances, high-energy overvoltages have to be
discharged here.
Surge currents exceeding 200 kA can be generated by cloud-to-ground but also cloud-to-cloud
lightning discharges.
As a rule, 50 % of the current is discharged via the lightning
protection system and the remaining 50 % is coupled
into the conductors and conductive parts in the building
and distributed uniformly. The closer a conductor is to the
lightning protection system, the greater is the launched
voltage (which can exceed 100 kV). The pulse duration can
be up to 0.5 m s. These powerful interference pulses are
discharged to earth directly at the incoming supply or main
distribution board by Type I lightning arresters and limited to
voltages below 6 kV. Power follow currents and backup fuse
values are just some of the aspects that need to be taken
into account here.
Depending on the local circumstances and the discharge
currents to be expected, sparkover gaps or varistor surge
arresters are used, taking into account the type of network.
Electrical system
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SURGE PROTECTION
SURGE PROTECTION
SURGE PROTECTION
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The basics of lightning and surge protection
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