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A.2
Suggestions for Configuring and Installing a Programmable Con-
troller
A programmable controller is often used as a component in a larger system.
The suggestions contained in the following warning are intended to help you
install your programmable controller safely.
!
ET 200U Distributed I/O Station
EWA 4NEB 812 6087–02b
Warning
Adhere to any safety and accident–prevention regulations applicable to
your situation and system.
If your system has a permanent power connection (stationary equipment)
that is not equipped with an isolating switch and/or fuses that disconnect
all poles, install either a suitable isolating switch or fuses in the building
wiring system. Connect your system to a ground conductor.
Before start–up, if you have units that operate using the main power sup-
ply, make sure that the voltage range setting on the equipment matches
the local main power voltage.
When using a 24 V supply, make sure to provide proper electric isolation
between the main supply and the 24 V supply. Use only power supplies
manufactured according to IEC 364–4–41 or HD 384.04.41 (VDE 0100,
part 410).
Fluctuations or deviations of the supply voltage from the rated value may
not exceed the tolerance limit specified in the technical specifications. If
they do, functional failures or dangerous conditions can occur in the elec-
tronic modules or equipment.
Take suitable measures to make sure that programs that are interrupted by
a voltage dip or power failure resume proper operation when the power is
restored. Make sure that dangerous operating conditions do not occur
even momentarily. If necessary, force an EMERGENCY OFF.
EMERGENCY OFF devices must be in accordance with EN 60204/
IEC 204 (VDE 0113) and be effective in all operating modes of the
equipment. Make certain to prevent any uncontrolled or undefined restart
when the EMERGENCY OFF devices are released.
Install power supply and signal cables so that inductive and capacitive
interference cannot affect the automation functions.
Install your automation system and its operative components so as to pre-
vent unintentional operation.
Automation equipment can assume an undefined state in the case of a
wire break in the signal lines. To prevent this, take the proper hardware
and software safety measures when linking the inputs and outputs of the
automation equipment.
Safety–Related Guidelines
A-3
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