Modelling and testing the coupling mechanisms involved in electromagnetic interference

What is it about?

The wiring configurations of grounding, floating and screening each have their unique features. To identify these features, measurements were carried out of the common mode rejection ratio of cable samples on a simple test rig. Accurate circuit models were used to emulate performance in each case. Assessment of the results provides some simple design guidelines to improve electromagnetic compatibility (EMC). Circuit modelling provides a rich source of ideas for improving EMC.

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Why is it important?

It introduces the concept of designing equipment to meet the requirements of EMC. The approach is based on the existence of a general circuit model to simulate the coupling mechanisms, the use of a test rig to assign values to the components of the model, and the ability to correlate the simulation of each specific model with the performance of the wiring configuration it represents. Such an approach is much better than one based on Design Regulations which invoke the concepts of Grounding Philosophy; that is on the concepts of the single-point ground, the equipotential ground, multipoint grounds, hybrid grounds, etc.