Siemens EK 746 Series Instrukcje Operacyjne Pobierz pdf (Strona 39)

Connecting up

SCALANCE W788-xPRO / W74x-1PRO/RR

A5E02280448-02, Release 11/2008

Safety extra low voltage

WARNING

Danger to life from overvoltage, fire hazard

SCALANCE W-700 devices are designed for operation with a directly

connectable safety extra-low voltage or with the power supply adapters

available as accessories (available only for the SCALANCE W786-xPRO

device). Therefore only safety extra-low voltage (SELV) with limited

power source (LPS) complying with IEC950/EN60950/VDE0805 may be

connected to the power supply terminals (exception: Power supply

adapter for 100 - 240 V AC for the SCALANCE W786-xPRO).

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).

The power supply unit to supply the SCALANCE W-700 must comply

with NEC Class 2 (requirements of class 2 for power supply units of the

"National Electrical Code, table 11 (b)") or SELV with LPS (Limited

Power Source) EN 60950-1. If the power supply is designed redundantly

(two separate power supplies), both power supplies must meet these

requirements.

Exceptions:

● Power supply with PELV (according to VDE 0100-410 or IEC 60364-

4-41) is also possible if the generated rated voltage does not exceed

the voltage limits 25 V AC or 60 V DC.

Redundant power supply

CAUTION

Setup with redundant power supply (Power over Ethernet + 24 V DC or 48 V DC)

To use a redundant 24 V power supply (or 48 V with SCALANCE W786) and Power

over Ethernet (PoE), a separate floating 24 V source (or 48 V source for W786)

must be available for each SCALANCE W-700. Otherwise there is no longer

isolation of the input voltages of different devices required for the PoE function and

functionality may be disturbed.

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Siemens EK 746 Series Instrukcje Operacyjne Strona 39