Propagation Of Electromagnetic Interference - Siemens SIMATIC RF600 System Manual

4.7.4

Propagation of electromagnetic interference

Three components have to be present for interference to occur in a system:
● Interference source
● Coupling path
● Interference sink
If one of the components is missing, e.g. the coupling path between the interference source
and the interference sink, the interference sink is unaffected, even if the interference source
is transmitting a high level of noise.
The EMC measures are applied to all three components, in order to prevent malfunctions
due to interference. When setting up a plant, the manufacturer must take all possible
measures in order to prevent the occurrence of interference sources:
● Only devices fulfilling limit class A of VDE 0871 may be used in a plant.
● Interference suppression measures must be introduced on all interference-emitting
● The design of the system must be such that mutual interference between individual
Information and tips for plant design are given in the following sections.
Interference sources
In order to achieve a high level of electromagnetic compatibility and thus a very low level of
disturbance in a plant, it is necessary to recognize the most frequent interference sources.
These must then be eliminated by appropriate measures.
Table 4- 1
Interference source
Contactors,
electronic valves
Electrical motor
Electric welding device
Power supply unit, switched-
mode
SIMATIC RF600
System Manual, 05/2012, J31069-D0171-U001-A13-7618
Figure 4-9 Propagation of interference
devices. This includes all coils and windings.
components is precluded or kept as small as possible.
Interference sources: origin and effect
4.7 Guidelines for electromagnetic compatibility (EMC)
Interference results from
Contacts
Coils
Collector
Winding
Contacts
Transformer
Circuit
RF600 system planning
Effect on the interference sink
System disturbances
Magnetic field
Electrical field
Magnetic field
Electrical field
Magnetic field, system disturbance,
transient currents
Electrical and magnetic field, system
disturbance
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