Wiring according to EMC
8
Electrical installation
8.2
l
8.2-1
EDSPM-TXXX-3.0-04/2004
8.2 Wiring according to EMC
General notes
•
The electromagnetic compatibility of the I/O system IP20 depends on the type and accuracy of the installation. Special attention should be
paid to:
– Assembly
– Shi elding
–Earthing
•
Any other installation set-ups require the system to be checked for compliance with the EMC limit values for assessment of conformity with
the EMC Directive. This applies e.g. to the following:
– Use of unshielded cables
•
Responsibility f or compliance with the EMC Directive is with the user.
– It can be assumed, if the following measures are observed, that no EMC probl ems will arise during operation and that the EMC Direc tive
and / or the EMC Act, respectively, is complied with.
– Operating devices near the system that do not meet the CE standard in terms of disturbance immunity EN 61000-4-2, may cause
electromagnetic interference to these devi ces by the decentralised I/ O system IP20.
Assembly
•
Connect DIN rail to earthed mounting plate:
– Mounting plates with conductive surfaces (zinc-coated or stainless steel) allow permanent contact.
– Painted plates are not suitable for installation in accordance with the EMC.
•
If you use several mounting plates:
– Connect the mounting plates elec trically with a surface as l arge as possible (e.g. with copper bands).
•
When laying the cables, ensure spatial separation from signalling and mains cables.
•
Route the cables as close as possible to the reference potential. Freely suspended cables act like aerials.
Shielding
•
If possible, use only cables with braids.
•
The shield coverage should be in excess of 80%.
•
Data lines for serial coupling always require metallic or metallised plugs. Connect the shield of the da ta line to the plug housing.
•
Usemetalcableclampstoattachthebraids.
•
Connect shield to shield rail inside the switchgear cabinet.
•
Connect the shields of analog control cable s at one end (either to the sensor or as closely as possibl e to the analog module input).
Earthing
•
Earth all metallically conductive components with suitable cables from a central earthing point (PE bar).
•
Comply with the minimum cross-sections defined in the safety instructions:
– It is not the c able cross-section that is decisive for EMC, but instead the cable surface and large-surface contact.
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