Connecting up
4.1 Lightning protection, power supply, and grounding
SCALANCE W786-2HPW
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Operating Instructions (Compact), 06/2007, A5E01186485
Safety extra low voltage
WARNING
Danger to life from overvoltage, fire hazard
SCALANCE W78x / W74x devices are designed for operation with a directly connectable
safety extra-low voltage or with the power supply adapters available as accessories
(available only for SCALANCE W786 devices). Therefore only safety extra-low voltage
(SELV) with limited power source (LPS) complying with IEC950/EN60950/VDE0805 may
be connected to the power supply terminals (exception: Power supply adapter for 110 - 230
V AC for the SCALANCE W786).
The power supply unit to supply the SCALANCE W78x / W74x must comply with NEC
Class 2 (requirements of class 2 for power supply units of the "National Electrical Code,
table 11 (b)") or SELV with LPS (Limited Power Source) EN 60950-1. If the power supply is
designed redundantly (two separate power supplies), both power supplies must meet these
requirements.
Exceptions:
•
Power supply with PELV (according to VDE 0100-410 or IEC 60364-4-41) is also
possible if the generated rated voltage does not exceed the voltage limits 25 V AC or 60
V DC.
Earthing
CAUTION
Damage to the device due to potential differences
There must be no potential difference between the following parts otherwise there is a risk
that the device will be destroyed:
•
Ground potential of the power supply and ground potential of the antenna ground.
•
Ground potential of the power supply and a grounded housing.
•
Ground potential of the power supply and the ground potential of the device connected
to Industrial Ethernet (for example PC, AS-300, AS-400 etc.)
Connect both grounds to the same foundation earth or use an equipotential bonding cable.
