Current barriers to confine high frequency common mode currents

Abstract

A commercially produced three phase power line filter is submitted to a Current Barrier (CB) Electro-Magnetic Compatibility (EMC) zoning strategy as an attempt to confine high frequency common mode currents. The intent of the paper is not to show how to build a ‘perfect’ filter, since this is known. The paper is about understanding why a theoretically high quality filter in practice can still fail in providing the expected performance. It was shown in earlier work that the filter, due to mechanical constraints (size, mounting bracket), had an improper grounding scheme for attenuating high frequency components of common mode currents. A solution for improving the total system is diverting the high frequency components of the common mode current before reaching the filter by applying a CB. In implementation this is achieved by creating a short circuit for high frequency common mode currents, which is the concept of interest in this paper.