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Connection
6.2 Power supply
SCALANCE W1788-x / W1748-1
Operating Instructions, 03/2022, C79000-G8976-C484-05
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6.2 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
There are two options for the power supply:
•
Direct infeed via the 4-pin M12 socket 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 8-pin M12 Ethernet interface P2 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 (AWG20) to 1.5 mm 2 (AWG20) cross-section per wire. The
temperature stability must be at least 105 °C.
• With redundant power supply: Four-wire cable with 0.5 (AWG20) to 1.5 mm 2 (AWG20)
cross-section per wire. The temperature stability must be at least 105 °C.
• Permitted tensile load at least 100 N.
• 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.