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4
must be protected accordingly. The same applies to the transmission
systems with external antennas which are only exposed to surges
resulting from the field of the lightning channel [5].
A practical solution for the direct installation of protective devices
into intelligent transformer substations which considers the possible
threat potential is, for example, a complete system for measuring,
control and telecontrol systems in a single enclosure (see Figure 2).
This application includes, for example, network analysis, integration of
electronic meters, short-circuit indicators and communication devices.
To ensure the required availability, the system in a compact enclosure
is protected from surges by adequate arresters.
This is achieved by DEHN surge arresters for power supply
systems and arresters which are specifically designed for use in wire-
less-applications for coaxial device and antenna interfaces (available
with SMA, BNC or N-connection for bushing installation). Since only
surges are to be expected due to the restrictions described before
and the secondary technology is directly integrated in an intelligent
transformer substation, Type 2 and Type 3 arresters are sufficient in
this case. In this particular application for protecting the secondary
technology in an intelligent transformer substation, the neutral point of
the transformer is directly earthed in addition to the surge protection
measures mentioned. This clearly differentiates the place of installation
‘substation’ from other places of installation since possible interference
impulses on the low-voltage side of the system are discharged via the
earthed low-impedance neutral point of the transformer. In addition to
theoretical considerations, practical tests of such overall systems can
be performed in DEHN’s in-house test laboratory [6].
Conclusion
Since the energy and data landscape is becoming increasingly complex
and highly networked, the probability of damage to electronic equip-
ment caused by electromagnetic interference significantly increases.
This is due to the broad introduction of electronic devices and systems
and their decreasing signal levels (and thus increasing sensitivity). Even
though destruction of electronic components is often not spectacular,
it frequently leads to long operational interruptions.
Consequential damage and the costs for clarifying
liability issues are sometimes considerably higher
than the actual hardware damage [7]. Numerous dif-
ferent lightning and surge protection components are
available for preventing such damage in smart grids
depending on the relevant requirements. In this con-
text, it is important to consider all potential points of
injection, namely both power supply and information
technology and communication systems. Space-sav-
ing and powerful arresters with CI technology and
Lifetime Indication can offer additional benefits. To
achieve a consistent and functioning surge protection
concept, energy coordination between the arrester
types according to IEC/EN 62305-4 must be ensured.
To complement surge protection and to ensure a
complete and comprehensive protection system, an
external lightning protection system (air-termination
system, down conductor and particularly earth-termi-
nation system) should be additionally installed and safety equipment
should be worn in the intelligent transformer substation. An important
topic is, for example, the correct dimensioning of earth-termination
systems for transformer stations with respect to the current carrying
capability and corrosion, which are described in separate papers [8, 9].
Such an overall protection system meets the increasing demands the
industrial society places on a stable and reliable power supply. They
require highly available distribution networks with minimum downtime,
thus ensuring increased supply reliability and availability.
References
[1] Wiersch M. Surge protection for smart grids – High system
availability as well as safe and trouble-free operation. Ew volume
114 (2015), H. 1.
[2] WAGO Kontakttechnik GmbH & Co. KG, Minden: http://www.
.
[3] DEHN + SÖHNE. Lightning Protection Guide, 3rd updated edition,
July 2013.
[4] Forum Netztechnik/Netzbetrieb im VDE (FNN): Substations –
Recommendations for dimensioning, installation, retrofitting and
operation. Berlin, 2013.
[5] DEHN + SÖHNE GMBH + : Intelligent substations - Surge
protection for the secondary technology in intelligent transformer
substations. Neumarkt, 2012
[6] DEHN + SÖHNE GMBH + . DEHN tests and analyses –
DEHN test centre (brochure No. 113). Neumarkt, 2014.
[7] Landers, EH. Zahlmann, P. EMC - Lightning protection for electri-
cal and electronic systems within structures. VDE Verlag GmbH,
Berlin, 3rd edition. 2013.
[8] Biebl, P, Seitz, T, Pfister, N. Dimensioning of earth-termination
systems for transformer stations with regard to the current
carrying capacity and corrosion. netzpraxis. volume 50 (2011).
Issues 3 and 4.
[9] Müller, KP. Corrosion damage on earthing systems Elektroprak-
tiker. Edition 9. 2010. HUSS-MEDIEN GmbH Berlin.
DEHN surge protective device for power supply, information technology
and communication systems.
52 ENERGY EFFICIENCY MADE SIMPLE 2015