This is the 5th article . of our ”EMC awareness” series. At this point, before addressing the coupling path, occuring from (or to) the power mains, it was in order to review a solution that is widely involved in controlling Conducted, Radiated and Crosstalk EMI situations: the use of shielded conductors. The subject is not that simple and requires some insight. This article will explain as clearly as possible for the non-specialist how a cable shield works, how much EMI reduction can be expected, and why the choice of certain cables or installation practices will result in mediocre results.
The former articles, after a broad overview of the EMC subject, covered the principal Military & Civilian Norms and Test methods, insisting on the legal inforcement of these verifications in European countries, who turned them into mandatory laws.
We also introduced the source/coupling-path/ victim concept, essential to a comprehensive approach of EMC. Most of the time, it is the coupling path between the culprit source and the victim equipment that is the crux of the problem, hence of its solutions, so the 5 essential coupling mechanisms wer listed, by which EM Interference take place. Although any equipment can be alternately the victim, or the source, of an EMI problem, we focused on EM susceptibility as being the manifestation that appears first in the designer’s or field engineer’s worries.
Nevertheless, emissions problems sooner or later may show-up, but since coupling mechanisms are reciprocal, the author has taken the choice of always reviewing susceptibility situations first, because once understood, the comprehension of emission mechanisms would follow easily. The 3rd article treated the frequent mechanism of Common Impedance Coupling, and the 4th article described two coupling paths where the interference occurs through Radio propagation or near-induction coupling (Crosstalk).
At this point, before addressing the coupling path, occuring from (or to) the power mains, it was in order to review a solution that is widely involved in controlling Conducted, Radiated and Crosstalk EMI situations: the use of shielded conductors. The subject is not that simple and requires some insight. This article will explain as clearly as possible for the non-specialist how a cable shield works, how much EMI reduction can be expected, and why the choice of certain cables or installation practices will result in…
Dear colleague,
This text is unfortunately locked for further reading, but you can read all Michel Mardiguian’s texts and course material about EMC in the new book “Everything you always wanted to know about EMC but were afraid to ask”. Click for more information!
