Installation manual

Assembling and Installing Systems

A-8

S7-400 and M7-400 Programmable Controllers Hardware and Installation

A5E00069481-04

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.