Assembling and Installing Systems
A-5
AutomationSystem S7-400 Hardwareand Installation
A5E00850741-01
A.2 Principles of System Installation for EMC

Definition: EMC

EMC (electromagnetic compatibility) describes the capability of electrical apparatus
to operate without faults in a given electromagnetic environment, without being
affected by the environment and without affectingit in an unacceptable manner.
Introduction
Although the S7-400 and its components were developed for operation in an
industrial environment and meet high EMC requirements, you should carry out
EMC planning before installing your control system, taking possible interference
sources into account and incorporating them in your observations.

Possible Effects of Interference

Electromagnetic interference can affect the programmable controller in different
ways:
Electromagnetic fields which directly affectthe system
Interference picked up via bus signals (PROFIBUS DP,etc.)
Interference acting via the process wiring
Interference reaching the system via the power supply and/or protective ground
Figure A-1 shows the possible routes for electromagnetic interference.
Electromagnetic
fields
Bus signal Process wiring
Protective ground Power supply module
Figure A-1 The Possible Routes for Electromagnetic Interference