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also be used for PoE (Power over Ethernet) applications, can
be installed. No matter if it is an ISDN or ADSL connection –
the data lines of devices which provide a connection to the
outside world are also protected by the relevant surge protec-
= tive devices.
~
In case of power plants with central inverters, generator junc-
tion boxes with additional measuring sensors are installed in
the field. In case of power plants with string inverters (Figure
9.19.13), their integrated string monitoring system takes
over this task. In both cases, the measured values from the
data line d.c. or a.c. monitoring generator field are transmitted via data interfaces. The data lines from
cables junction box
the service room are installed together with the power cables
(a.c. or d.c.). Due to the short line lengths of field bus sys-
Figure 9.19.14 Basic principle of induction loops in PV power tems, data cables are individually routed transversely to the
plants
module racks. In case of a direct lightning strike, these trans-
verse connections also carry partial lightning currents which
Surge protection measures for information may damage the input circuits and cause flashover to power
techno logy systems cables. Large induction loops are formed due to the interac-
Data from the field as well as data acquired from remote main- tion of power cables, metal module racks rows and data lines
tenance by the plant operator and capacity measurements (Figure 9.19.14). This is an ideal environment for transients
and control by the grid operator are collected in operations caused by lightning discharges which can be injected into
buildings. To ensure that the service staff is able to specifically these lines. Such voltage peaks are capable of exceeding the
determine causes of failure via remote diagnostics and elimi- insulation strength / dielectric strength of these systems which
nate them on site, reliable data transfer must be ensured at leads to surge damage. Therefore, SPDs must be installed in
any time. The string and inverter monitoring system, weather these monitoring generator junction boxes or in the decentral-
data acquisition unit, anti-theft protection and external com- ised string inverters to protect data transmission. Cable shields
munication system are based on different physical interfaces. must be connected to all connection points in line with the
Wind and radiation sensors with analogue signal transmission EN 50174-2 standard (section 5.3.6.3). This can also be
can be protected by DEHNbox DBX. Thanks to its actiVsense achieved by indirect shield earthing to prevent malfunction
technology, DEHNbox DBX can be used for signal voltages such as ripples and stray currents. BLITZDUCTOR XT, for exam-
up to 180 V and automatically adapts the voltage protection ple, can be used together with an EMC spring terminal of type
level. BLITZDUCTOR XT is ideally suited to protect an RS 485 SAK BXT LR for indirect shield earthing.
interface for communication between the inverters. DEHNgate
BNC VC devices are used to protect CCTV systems with coaxial Consistent lightning and surge protection for all systems al-
video transmission which is used for anti-theft protection sys- lows to considerably increase the performance ratio of these
tems. If the sub-stations of large-scale PV power plants are power plants. The service and maintenance time as well as re-
interconnected via Ethernet, DEHNpatch M CAT6, which can pair and spare part costs are reduced.

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