Siemens SIMATIC NET SCALANCE W720 Operating Instructions Manual page 33

Supply voltage {xe "Safety extra low voltage"}{xe "Supply voltage"}
Safety extra low voltage
The equipment is designed for operation with Safety Extra-Low Voltage (SELV) by a
Limited Power Source (LPS).
This means that only SELV / LPS (Limited Power Source) complying with IEC 60950-1 / EN
60950-1 / VDE 0805-1 must be connected to the power supply terminals or the power
supply unit for the equipment power supply must comply with NEC Class 2, as described by
the National Electrical Code (r) (ANSI / NFPA 70).
If the equipment is connected to a redundant power supply (two separate power supplies),
both must meet these requirements.
Transient overvoltages
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).
Grounding
Danger to life from overvoltage, fire hazard
When using outdoor antennas, the shared or even grounded pin of the circuit must be
connected to the shield of the coaxial cable and with all touchable conductive parts and
circuits. Otherwise, in the event of a fault there may be illegally high voltages on touchable
parts.
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:
• Grounding pin of the SCALANCE W700 and the ground potential of the antenna.
• Grounding pin of the SCALANCE W700 and the ground potential of a device connected
• Grounding pin of the SCALANCE W700 and the shield contact of the connected
Connect both grounds to the same foundation earth or use an equipotential bonding cable.
SCALANCE W760/W720
Operating Instructions, 10/2019, C79000-G8976-C322-11
WARNING
WARNING
WARNING
over Ethernet.
Ethernet cable.
5.1 Lightning protection, power supply and grounding
Connection
33