Siemens Automation System S7-400 - Manual (Page 171)

Assembling and Installing Systems
A-3
Automation System S7-400 Hardware and Installation
A5E00850741-01
120/230 VAC Supply
The following table shows which points you must observe when connecting the
S7-400 to a 120/230 VAC supply.
With ... ... You Must Ensure ...
buildings that suitable external lightning protection measures are
provided.
supply cables and signal
lines
that suitable internal and external lightning protection
measures are provided.
stationary equipment and
systems without all-pole
disconnector
that a supply disconnector (switch) is installed in the
building.
load power supplies and
power supply modules
that the set line voltage range corresponds to the local line
voltage.
all circuits of the S7-400 that fluctuations of line voltage from the rated value are
within permissible tolerances (see Technical Data of the
modules).
residual-current devices
(RCDs)
that the RCD is suitable for the total discharge currents of
the power supply module.
24 VDC Supply
The following table shows the points you must observe when connecting the
S7-400 to a 24 VDC supply.
With ... ... You Must Ensure ...
buildings that suitable external lightning protection measures are
provided.
24 VDC supply cables and
signal lines
that suitable internal and external lightning protection
measures are provided.
24 V supply that the supply voltage produced is an isolated extra-low
voltage.
load power supplies that only isolated load current power supplies are used.
Protection Against External Electrical Effects
The following table shows what you must observe for protection against external
electrical effects.
With ... ... You Must Ensure ...
all plants and systems in
which the S7-400 is
installed
that the plant and all system sections are properly
connected to protective ground to discharge
electromagnetic interference.
connecting cables and
signal lines
that all cables are correctly routed and connected.
signal lines that an open circuit in a signal line does not place the
equipment in an undefined state.