Siemens SCALANCE X204RNA Operating Instructions Manual page 38

Connection
6.1 Power supply
The SCALANCE X204RNA is designed for operation with safety extra-low voltage (SELV).
This means that only safety extra-low voltages (SELV) complying with IEC950/EN60950/
VDE0805 can be connected to the power supply terminals.
Measures must be taken to prevent transient overvoltages of more than 40% of the rated
voltage. This is the case if the devices are operated exclusively with SELV (Safety Extra
Low Voltage).
The power supply unit for the SCALANCE X204RNA power supply must meet NEC Class
2, as described by the National Electrical Code(r) (ANSI/NFPA 70).
The power of all connected power supply units must total the equivalent of a power source
with limited power (LPS limited power source).
If the device is connected to a redundant power supply (two separate power supplies), both
must meet these requirements.
The signaling contact can be subjected to a maximum load of 100 mA (safety extra-low
voltage (SELV), 24 VDC).
Never operate the SCALANCE X204RNA with AC voltage or DC voltage higher than 28.8
V DC.
24 VDC power supply
CAUTION
If the SCALANCE X204RNA is supplied over long 24 V power supply lines or networks,
measures are necessary to prevent interference by strong electromagnetic pulses on the
supply lines. These can result, for example, due to lightning or switching of large inductive
loads.
One of the tests used to attest the immunity of the SCALANCE X204RNA to
electromagnetic interference is the "surge immunity test" according to EN61000-4-5. This
test requires overvoltage protection for the power supply lines. A suitable device is, for
example, the Dehn Blitzductor VT AD 24 V type no. 918 402 or comparable protective
element.
Vendor: DEHN+SÖHNE GmbH+Co.KG, Hans-Dehn-Str.1, Postfach 1640, D-92306
Neumarkt, Germany.
38
WARNING
SCALANCE X204RNA SCALANCE X204RNA EEC
Operating Instructions, , C79000-G8976-C294-03
(PRP)