Classification of Signals according to their EMC Performance

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

Class 2 Slightly sensitive

Class 3 Slightly interfering

Class 4 Interfering Signal is very sensitive.

Signal is sensitive. Can disturb class 1 cables.

Signal disturbs class 1 and 2 cables

Signal disturbs other classes signals  Low level circuits with analog output, instrument transformer ...  Measuring circuit (probes, instrument transformer ...)

 Low-level digital circuits (bus ...)  Low-level circuits with digital output, (instrument transformer ...)  Control circuit for resistive load  Low-level d.c. power supplies

 Control circuit for inductive loads (relay, contactor, coils, inverters ...) with corresponding protection  A.C. power supplies  Main power supplies for high power devices

 Welding machine  Power circuits in general  Electronic speed controller, switching power supplies ...