II - DCE FEL ČVUT v Praze

Mechanical Configuration of an Automation System with SIMATIC S7 Ex Modules
I/O Modules with Intrinsically-Safe Signals
C79000-G7076-C152-04
2. Follow the code of practice for line routing when wiring
Subdivide the cabling into line groups.
(AC power cables, supply lines, Ex and non-Ex signal lines, data lines)
Always install power cables and signal or data lines in separate ducts or
bundles.
Route the signal and data lines as closely as possible to grounded surfaces
such as supporting bars, metal rails, cabinet sheet metal panels.
Install Ex and non-Ex signal lines in separate ducts.
3. Ensure that line shields are properly secured
Data lines should be shielded when laid. The shield should be connected
at both ends.
Analog lines should be shielded when laid. When low-amplitude signals
are transmitted, it may be advantageous if the shield is connected at only
one end.
For Ex signal lines, connect the line shields only at the sensor or actuator
end. Ensure that the connected shield continues without interruption as far
as the module, but do not connect it there.
Ensure that the shield has a low-impedance connection to the
equipotential bonding conductor.
Use metal or metallized plug housings for shielded data lines.
4. Implement special EMC measures for particular applications
For all inductances, fit quenching elements provided they are not already
contained in the output modules.
Use incandescent bulbs for lighting the cabinets and avoid fluorescent
lamps.
5. Provide a standard reference potential and ground all electrical
apparatus if possible
Take care to ensure specific grounding measures. Grounding of the
control system is a protective and functional measure.
System elements and cabinets should be connected in star-configuration
to the ground/protective conductor system. In this way you can avoid the
formation of ground loops.
In the event of potential differences between system elements and
cabinets, install adequately rated equipotential bonding conductors.
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