Siemens SIMATIC NET SCALANCE W774-1 - Page 37

Connection
5.1 Lightning protection, power supply and grounding
SCALANCE W774-1 /W734-1
Operating Instructions, 07/2020, C79000-G8976-C325-14
37
Supply voltage
WARNING
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.
WARNING
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
WARNING
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 di
fference 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 Ethernet.
• Housing of the SCALANCE W700 and the shield contact of the connected Ethernet
cable.
Connect both grounds to the same foundation earth or use an equipotential bonding
cable.