Prediction of Common Mode Current in Cable Harnesses


Common mode current on cable harnesses is often responsible for system level EMI, but is difficult to predict early in the design process. Typical component level measurements are unhelpful as common mode currents may change dramatically when the component is placed in the system. A methodology is developed in the following paper to estimate common mode current in system-level applications based on component-level measurements. Estimates are made by assuming that termination impedances can be approximated as shorts or opens with respect to the characteristic impedance of the harness. Furthermore, the dominate sources of common mode current for each set of terminations (open or short) should have similar source impedances. With these assumptions, the common mode current on the harness can be approximated from the sum of currents on two equivalent circuits terminated with an open and a short. The source characteristics of each equivalent circuit can be determined from two measurements of common mode current on harnesses of two different lengths. The equivalent circuits can be used to estimate common mode currents on harnesses of arbitrary length and characteristic impedance.

Meeting Name

2018 IEEE International Symposium on Electromagnetic Compatibility and 2018 IEEE Asia-Pacific Symposium on Electromagnetic Compatibility, EMC/APEMC 2018 (2018: May 14-18, Singapore)


Electrical and Computer Engineering


This paper is based upon work supported in part by the National Science Foundation under Grant No. IIP-1440110.

Keywords and Phrases

Building components; Cables; Computational electromagnetics; Equivalent circuits; Level measurement; Characteristic impedance; Common mode currents; Component levels; Electromagnetic emissions; Electromagnetic modeling; Measurements of; Source characteristics; Source impedance; Electromagnetic compatibility; Component level test; Equivalent harness model

International Standard Book Number (ISBN)


Document Type

Article - Conference proceedings

Document Version


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© 2018 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

18 May 2018