Omron CJ Series Operation Manual page 21

Conformance to EC Directives
6-4 Relay Output Noise Reduction Methods
Countermeasures
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2. You must use reinforced insulation or double insulation for the DC power
supplies used for the communications power supply and I/O power sup-
plies.
3. CS/CJ-series PLCs complying with EC Directives also conform to the
Common Emission Standard (EN61000-6-4). Radiated emission charac-
teristics (10-m regulations) may vary depending on the configuration of the
control panel used, other devices connected to the control panel, wiring,
and other conditions. You must therefore confirm that the overall machine
or equipment complies with EC Directives.
The CS/CJ-series PLCs conforms to the Common Emission Standards
(EN61000-6-4) of the EMC Directives. However, noise generated by relay out-
put switching may not satisfy these Standards. In such a case, a surge sup-
pressor must be connected to the load side or other appropriate
countermeasures must be provided external to the PLC.
Countermeasures taken to satisfy the standards vary depending on the
devices on the load side, wiring, configuration of machines, etc. Following are
examples of countermeasures for reducing the generated noise.
(Refer to EN61000-6-4 for more details.)
Countermeasures are not required if the frequency of load switching for the
whole system with the PLC included is less than 5 times per minute.
Countermeasures are required if the frequency of load switching for the whole
system with the PLC included is 5 times or more per minute.
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