Siemens S7-400 Rule 4 Special EMC Measures, Rule 5 Standard Reference Potential, See also

Assembling and Installing Systems

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 sufficient rating when potential differences exist or 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

A-8	Automation System S7-400	Hardware and Installation
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