VIPA SSM-BG41 - The most Important Basic Rules to Guarantee EMC

Structure guidelines Manual BG41/BG42/BG43
5-32 Rev. 99/49
5.7.3 The most important basic rules to guarantee EMC
In order to guarantee EMC, it often suffices when one keeps to a few elementary rules. Therefore
observe the following guidelines when constructing the controls:
•= Ensure that you use a good configured two-dimensional earth of inactive metal parts when
setting up an automation piece of equipment.
- Establish a central connection between the ground and the earth electrode/protective
earth conductor system.
- Connect all inactive metal parts on a large area and with little impedance.
- Use no aluminium parts if possible. Aluminium oxidises easily and is therefore less
suitable for the earth.
•= Ensure to have a proper cable tracing when wiring.
- Divide the cabling into cable groups.
(Heavy current, current supply cables and signal and data cables).
- Always lay the heavy current cables and the signal and data cables in separate
channels or bundles.
- Lead the signal and data cables as tight as possible on the ground area
(e.g. supporting bars, metal rails, thin metal barriers).
•= Ensure to fasten the cable screens perfectly.
- Data cables are to be laid shielded. The screen is to be applied on both sides.
- Analogue cables are to be laid shielded. The laying of screens on one side can be
advantageous when transmitting signals with small amplitudes.
- Lay the cable screens largely on a screen/protective earth conductor rail after the
barrier entry and secure the screens with cable clamps.
- Ensure that the screen/protective earth conductor rail is connected with little
impedance to the barrier.
- Use metallic or metallized connector housing for screened data cables.
•= Use special EMC measures in particular application cases.
- Wire all inductances with capacities, which are not controlled by VIPA building
blocks.
- Use incandescent lamps to illuminate the barriers and avoid fluorescent
lamps.
•= Create a uniform reference potential and earth all resources where possible.
- Be aware of the intended input of earthing measures. The earthing of the control
serves as a protection and functional measure.
- Connect the plant parts and barriers with the central and expanded equipment in
stelliform with the earth/protection earth conductor system. The formation of earth
loops is therefore prevented.
- Lay in potential differences enough dimensioned potential equalization cables
between plant parts and barriers.