Connection
6.4 Power supply
SCALANCE W778-1 /W738-1
Operating Instructions, 07/2020, C79000-G8976-C450-06
43
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
)
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.
–
Power over Ethernet via the M12 Ethernet interface P2 (position
②
).
The power supply cannot be connected redundantly.
•
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
where NEC or CEC applies: Type PTLC or ITC
•
To connect the functional ground, use a copper cable of category 20 AWG or a cable
with a cross-section
≥
0.75 mm².
