Assembling and Installing Systems
A-8 AutomationSystem S7-400 Hardwareand Installation
A5E00850741-01
Rule 4: Special EMC Measures
Employ special EMC measures for particular applications (see Section 4.11).
•Fit suppressors to all inductors which are not controlled by S7-400 modules.
•Use incandescent bulbs or suppressed fluorescent lamps in the immediate
vicinity of your controller for illuminating cabinets or housings.
Rule 5: Standard Reference Potential
Create a standard reference potential; ground all electrical apparatus if possible
(see Sections 4.10 and 4.12).
•Install equipotential bonding conductors of sufficientrating when potential
differences existor are expected between sections of your system.
•Use specific grounding measures. Grounding the control system is a protective
and functional measure.
•Connect the system sections and cabinets containing central racks and
expansion racks to the grounding/protective ground system in a star
configuration. This prevents the formation of ground loops.
See also
Cable shielding, page A-13
Cabling outside buildings, page A-19
Cabling inside buildings, page A-17
Mounting of programmable controllers for EMC, page A-9