Siemens SIMATIC NET SCALANCE W786C Series Operating Instructions Manual page 41

Safety extra low voltage
Danger to life from overvoltage, fire hazard
SCALANCE W700 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 the SCALANCE W786 device). 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 100 - 240 VAC for the
SCALANCE W786).
Take measures to prevent transient voltage surges of more than 40% of the rated voltage.
This is the case if you only operate devices with SELV (safety extra-low voltage).
The power supply unit to supply the SCALANCE W700 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.
Exception:
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 VAC or 60 VDC.
Grounding
NOTICE
Damage to the device due to potential differences
To fully eliminate the influence of electromagnetic interference, the device must be
grounded. There must be no potential difference between the following parts, otherwise the
device or other connected device could be severely damaged:
• Housing of the SCALANCE W700 and the ground potential of the antenna.
• Housing of the SCALANCE W700 and the ground potential of a device connected over
• Housing of the SCALANCE W700 and the shield contact of the connected Ethernet
Connect both grounds to the same foundation earth or use an equipotential bonding cable.
If it is used outdoors, the device must always be connected to protective earth.
SCALANCE W786C
Operating Instructions, 07/2019, A5E03692138-12
WARNING
Ethernet.
cable.
5.2 Lightning protection, power supply and grounding
Connection
41