Basic Rule For Ensuring Emc - Siemens Simatic S7-300 CPU 31xC Series Installation And Operating Instructions Manual

Appendix
A.2 Protection against electromagnetic interference
A.2.2.3

3. Basic rule for ensuring EMC

Rule 3: Fixing the cable shielding
Ensure proper fixation of the cable shielding.
• Always use shielded data cable. Always connect both ends of the shielding to ground on
• Analog cables must always be shielded. For the transmission of low-amplitude signals it
• Directly behind the cable entry in the cabinet or enclosure, terminate the shielding on a
• Connections between the shielding/protective ground conductor bar and the
• Always install shielded data cables in metal/metallized connector housings.
See also
Cable shielding (Page A-12)
A.2.2.4 4. Basic rule for ensuring EMC
Rule 4: Special EMC measures
Take special EMC measures for particular applications.
• Connect anti-surge elements to all inductive devices not controlled by S7-300 modules.
• For cabinet or cubicle lighting in the immediate range of your controller, use incandescent
See also
How to protect digital output modules against inductive surge voltage (Page A-28)
A-6
a large area.
might prove to be more efficient to have only one side of the shielding connected to
ground.
large area of the shielding/protective ground bar and fasten it with the help of a cable
clamp. Then, route the cable to the module; however, do not connect the shielding once
again to ground in this place.
cabinet/enclosure must be of a low impedance.
lamps or interference suppressed fluorescent lamps.
S7-300, CPU 31xC and CPU 31x: Installation
Operating Instructions, Edition 08/2004, A5E00105492-05