YASKAWA iC9200 Series Manual page 39

iC9200 Series
Possible interference
causes
Basic rules for EMC
HB700 | CPU | PMC921xEx | en | 23-06
Electromagnetic interferences may interfere your control via different ways:
n Electromagnetic fields (RF coupling)
n Magnetic fields with power frequency
n Bus system
n Power supply
n Protected earth conductor
Depending on the spreading medium (lead bound or lead free) and the distance to the
interference cause, interferences to your control occur by means of different coupling
mechanisms.
There are:
n galvanic coupling
n capacitive coupling
n inductive coupling
n radiant coupling
In the most times it is enough to take care of some elementary rules to guarantee the
EMC. Please regard the following basic rules when installing your PLC.
n Take care of a correct area-wide grounding of the inactive metal parts when installing
your components.
– Install a central connection between the ground and the protected earth conductor
system.
– Connect all inactive metal extensive and impedance-low.
– Please try not to use aluminium parts. Aluminium is easily oxidizing and is there-
fore less suitable for grounding.
When cabling, take care of the correct line routing.
n
– Organize your cabling in line groups (high voltage, current supply, signal and data
lines).
– Always lay your high voltage lines and signal respectively data lines in separate
channels or bundles.
– Route the signal and data lines as near as possible beside ground areas (e.g.
suspension bars, metal rails, tin cabinet).
n Proof the correct fixing of the lead isolation.
– Data lines must be shielded.
– Analog lines must be shielded. When transmitting signals with small amplitudes
the one sided laying of the isolation may be favourable.
– Cables for frequency inverters, servo and stepper motors must be shielded.
– Lay the line isolation extensively on an isolation/protected earth conductor rail
directly after the cabinet entry and fix the isolation with cable clamps.
– Make sure that the isolation/protected earth conductor rail is connected impe-
dance-low with the cabinet.
– Use metallic or metallised plug cases for isolated data lines.
n In special use cases you should appoint special EMC actions.
– Consider to wire all inductivities with erase links.
– Please consider luminescent lamps can influence signal lines.
n Create a homogeneous reference potential and ground all electrical operating sup-
plies when possible.
– Please take care for the targeted employment of the grounding actions. The
grounding of the PLC serves for protection and functionality activity.
– Connect installation parts and cabinets with your PLC in star topology with the
isolation/protected earth conductor system. So you avoid ground loops.
– If there are potential differences between installation parts and cabinets, lay suffi-
ciently dimensioned potential compensation lines.
Industrial security and installation guidelines > Installation guidelines
Basics and mounting
39