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approaches can be derived from the relevant protection standards:
• Material damage and life hazard in case of direct lightning strikes
to a structure can be minimised by a conventional Lightning
Protection System (LPS) according to IEC/EN 62305-3 [3]
• To ensure protection of structures with electrical and electronic
systems, particularly if reliable operation and supply are essential,
these systems must be additionally protected from conducted and
radiated interference resulting from the Lightning Electromagnetic
Pulse (LEMP) in case of direct and indirect lightning strikes. This
can be achieved by a LEMP protection system according to
IEC/EN 62305-4 [3]
Possible solution approaches and criteria for
selecting arresters
A detailed risk assessment of the local threat potential (both for power
supply and information technology and communication systems) is
required to efficiently protect the technologies used for modern grid
expansion such as intelligent transformer substations [4], monitoring
and telecontrol systems, adjustable regulated distribution transformers
or longitudinal voltage controllers from the sources of damage. This
involves certain challenges, for example, lightning and surge protection
measures for the electronic components, lacking ease of maintenance
and the frequently compact design of the systems.
According to the IEC/EN 62305-2 [3] standard, the total risk of
lightning damage consists of the frequency of a lightning strike, the
probability of damage and the loss factor. If the technologies men-
tioned are assessed according to these criteria in conjunction with
practical experiences, you will get different individual results depending
on the local thunderstorm activity, design and place of installation.
To prevent galvanic coupling to the 20 kV medium-voltage overhead
line network or outgoing low-voltage lines as a result of a direct
lightning strike, a protective device must be installed in the main
low-voltage distribution board. This protective device must be selected
in such a way that it meets the requirements concerning the lightning
current carrying capability, short-circuit strength, follow current extin-
guishing capability and Temporary OverVoltages (TOV) characteristic.
A spark-gap-based Type 1 combined arrester with integrated back-up
fuse (CI technology or Circuit Interruption Fuse Integrated) is ideally
suited for this purpose. This integrated back-up fuse significantly saves
space and installation work compared to a separate arrester back-up
fuse and is adapted to the discharge capacity of the spark gap. This
ensures maximum performance and incorrect installation is avoided.
If only indirect lightning effects such as inductive or capacitive
coupling, conducted partial lightning currents or SEMP are to be
expected for the secondary technology according to a risk analysis
as per IEC/EN 62305-2 [3], Type 2 (sub-distribution board) and Type 3
(protection of terminal devices) surge arresters are sufficient. Type 2
arresters with the compact CI technology described are available for
restricted space conditions.
A surge arrester with integrated Lifetime Indication can be used
to implement a preventive maintenance concept. This Lifetime Indi-
cation detects pre-damage and indicates this status at an early stage
before the surge protective device fails. The arrester can therefore be
integrated in condition monitoring systems. This version has a higher
discharge capacity than conventional Type 2 arresters, thus increasing
the protective effect. In case of wired signal interfaces, injection is to
be expected and therefore these interfaces must be protected. A direct
lightning strike to the relevant conductor system or a nearby lightning
strike close to the relevant conductor system is possible in this case.
Therefore, a risk analysis must be performed and the components
IEC/EN 62305 2006: Lightning protection standard
IEC/EN 62305-1:
General principles
IEC/EN 62305-2:
Risk management
IEC/EN 62305-3:
Physical damage to structures and life hazard
IEC/EN 62305-4:
Electric and electronic systems within structures
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ENERGY EFFICIENCY MADE SIMPLE 2015