Coupling Mechanisms; Five Basic Rules For Securing Emc - Siemens SIWAREX WP251 Manual

Mounting
5.2 EMC-compliant installation
5.2.3

Coupling mechanisms

Depending on the propagation medium (conducted or non-conducted) and the distance
between the interference source and the device, interferences can enter the faulty device
through four different coupling mechanisms:
● Electrical coupling
● Capacitive coupling
● Inductive coupling
● Radiation coupling
5.2.4

Five basic rules for securing EMC

Observe these five basic rules to secure EMC.
Rule 1: Large area grounding contact
● When installing the devices, make sure that the surfaces of inactive metal parts are
properly bonded to chassis ground (see following sections).
● Bond all inactive metal parts to chassis ground, ensuring large area and low-impedance
contact (large cross-sections).
● When using screw connections on varnished or anodized metal parts, support contact
with special contact washers or remove the protective insulating finish on the points of
contact.
● Wherever possible, avoid the use of aluminum parts for ground bonding. Aluminum
oxidizes very easily and is therefore less suitable for ground bonding.
● Provide a central connection between chassis ground and the ground/protective
conductor system.
Rule 2: Proper cable routing
● Organize your wiring system into cable groups (high-voltage/power
supply/signal/measurement/data cables).
● Always route high-voltage and data cables in separate ducts or in separate bundles.
● Install the measurement cables as close as possible to grounded surfaces (e.g.
supporting beans, metal rails, steel cabinet walls).
Rule 3: Fixing the cable shielding
● Ensure proper fixation of the cable shielding.
● Always use shielded data cables. Always connect both ends of the data cable shielding to
ground on a large area.
● Keep unshielded cable ends as short as possible.
● Always use metal/metalized connector housings only for shielded data cables.
26
SIWAREX WP251
Manual, 12/2015, A5E37203357A