Power Supply - Siemens SCALANCE W778-1 Operating Instructions Manual

6.4

Power supply

Note
Galvanic isolation of the power supply unit
To ensure dielectric strength according to IEEE 802.3, the supplying 24 V power supply
unit must be galvanically isolated with a dielectric strength of 1500 VAC. The galvanic
isolation must also not be bridged by other devices connected to the same power supply
unit.
Note
All power supplies (24 V power supply unit or PoE) must not be connected to a mains
supply higher than 300 V and the overvoltage category II.
Information on the power supply
• For the power supply, there are two options with the SCALANCE W778/W738:
– Direct feed in via the four-pin M12 socket (position ①)
– Power over Ethernet via the M12 Ethernet interface P2 (position ②).
• For the direct feed-in of the power supply use copper cables with the following
properties:
– Round cable cross-section with 6 to 8 mm diameter.
– Two-wire cable with 0.5 to 1.5 mm2 cross-section per wire.
– Permitted tensile load at least 100 N. - UL
– Listing of the cables according to the national installation regulations. In areas
• To connect the functional ground, use a copper cable of category 20 AWG or a cable
with a cross-section ≥ 0.75 mm².
SCALANCE W778-1 /W738-1
Operating Instructions, 07/2020, C79000-G8976-C450-06
The power supply can be connected redundantly. The inputs L1/L2 are decoupled
There is no distribution of load. The power supply unit with the higher output
voltage supplies the device alone.
The power supply cannot be connected redundantly.
where NEC or CEC applies: Type PTLC or ITC
Connection
6.4 Power supply
43