EMC_PLC

Cabling

Classification of Signals according to their EMC Performance Reasons for the classification In an industrial environment, signals are classified in four categories according to their EMC performance. This classification is required for the application of cabling rules.

Classification of signals The following table shows the classification of signals according to their EMC performance: Classification

EMC performance Example of a circuit or device with cables in this class

Class 1 Sensitive

Signal is very sensitive.

 Low level circuits with analog output,

instrument transformer ...

 Measuring circuit (probes, instrument

transformer ...)

Class 2 Slightly sensitive

Signal is sensitive.  Low-level digital circuits (bus ...)

Can disturb class 1  Low-level circuits with digital output, cables. (instrument transformer ...)  Control circuit for resistive load  Low-level d.c. power supplies

Class 3 Slightly interfering

Signal disturbs class 1 and 2 cables

 Control circuit for inductive loads (relay,

Class 4 Interfering

Signal disturbs other classes signals

 Welding machine

contactor, coils, inverters ...) with corresponding protection  A.C. power supplies  Main power supplies for high power devices  Power circuits in general  Electronic speed controller, switching power

supplies ...

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33002439 10/2019