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the control cabinets in the tower base to the nacelle. Shielded
copper cables are used to connect the actuators and sensors
with the control cabinets. Since interference by an electromag-
netic environment is excluded, the glass fibre cables do not
have to be protected by surge arresters unless they have a
metal sheath which must be integrated in the equipotential
bonding system either directly or by means of surge protective
devices.
In general, the following shielded signal lines connecting the
actuators and sensors with the control cabinets must be pro-
tected by surge protective devices:
¨ Signal lines of the weather station and aircraft warning
light on the sensor mast
¨ Signal lines routed between the nacelle and the pitch sys-
tem in the hub
¨ Signal lines for the pitch system
¨ Signal lines to the inverter
¨ Signal lines to the fire extinguishing system Figure 9.16.10 Protection of wind measurement equipment
(anemometer)
Signal lines of the weather station
The signal lines (4 – 20 mA interfaces) between the sensors
of the weather station and the switchgear cabinet are rout- protective device is a prewired standard patch cable with inte-
ed from LPZ 0 B to LPZ 2 and can be protected by means of grated surge arrester.
BLITZDUCTOR XT ML4 BE 24 or BLITZDUCTOR XT ML2 BE S 24 Whether the signal lines for the pitch system must be pro-
combined arresters (Figure 9.16.10). These space-saving tected by surge protective devices depends on the sensors
combined arresters with LifeCheck feature protect two or four used which may have different parameters depending on the
single cores sharing a common reference potential as well manufacturer. If, for example, sensors supplied with 24 V d.c. or
as unbalanced interfaces and allow direct or indirect shield lower voltages are used, BLITZDUCTOR BXT ML4 BE 24 surge
earthing. Shield terminals with a flexible spring element for arresters are ideally suited to protect these signal lines. These
permanent low-impedance shield contact with the protected arresters can be installed in conformity with the lightning pro-
and unprotected side of the arrester are used for earthing the tection zone concept at the boundaries from LPZ 0 A to LPZ 2
shield. and higher. Surge protective devices should be installed on
If the wind measurement equipment (anemometer) is fitted both sides, namely in the pitch system and in the controller.
with a heating system, BLITZDUCTOR BVT ALD 36 combined
arresters may be installed. These DIN rail mounted combined Condition monitoring
arresters are energy-coordinated with the surge protective The availability of wind turbines, especially that of offshore
devices of unearthed d.c. power supply systems (Figure wind turbines, increasingly gains importance. Therefore, light-
9.16.10). ning current and surge arresters must be monitored for signs
of pre-damage (condition monitoring).
Signal lines for the pitch system The specific use of condition monitoring allows to plan service
An universal DEHNpatch DPA M CLE RJ45B 48 surge arrester work, thus reducing costs.
can be used if information between the nacelle and the pitch BLITZDUCTOR XT arresters for information technology systems
system is exchanged via 100 MB Ethernet data lines. This ar- with integrated LifeCheck feature are a simple and ideal moni-
rester is designed for Industrial Ethernet and similar applica- toring system that detects pre-damage at an early stage and
tions in structured cabling systems according to class E up to allows to replace pre-damaged arresters in the next service
250 MHz for all data services up to 48 V d.c. and protects four interval. LifeCheck permanently monitors the status of the
pairs (Figure 9.16.11). arresters free of potential since the LifeCheck status is read
Alternatively, a DEHNpatch DPA M CAT6 RJ45S 48 arrester can out via contactless RFID technology. Like an early warning sys-
be used to protect the 100 MB Ethernet data lines. This surge tem, LifeCheck reliably detects imminent electrical or thermal

www.dehn-international.com LIGHTNING PROTECTION GUIDE 351