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Rockwell Automation Publication 1718-IN001A-EN-E - June 2020
1718 Ex I/O
EMC filters are used in many devices to divert any noise to ground. High-
frequency noise occurring in the same way on both lines is dissipated
symmetrically through the capacitor impedances and does not appear as a
differential signal.
Wiring
Lay the signal lines such that they are separate from the power cables. AC
voltages and current spikes can induce stray voltages in neighboring lines. Use
shielded cables for EMC-tested devices.
Separate grounding bars from the shielding (see IEC/EN 60079-14). The
shielding is grounded at one point (to PA in explosion-hazardous areas).
Field wiring
Depending on the application, the shielding of the wiring must be grounded at
one point or at both ends. If possible, avoid grounding at both ends to prevent
ground loops and ensure no current flows through the shielding in the case of a
ground potential difference.
For sound results, ground one end of the cable if the cable is laid on a grounded
metal cable support. To reduce interference and ensure that only small areas are
WARNING:
Improperly installed wiring can cause explosive mixtures to ignite.
Observe the wiring specifications set out in IEC/EN 60079-14 for laying lines in an
explosion hazardous area.
