Impact of Proximity Effects on the Magnetic Field Produced by a Multiconductor Cable

Author(s):

Timothy M. Pritchett

Abstract:

We quantify the impact of proximity effects on the magnetic flux density (𝐵=𝐵-field) due to the current in one of the conductors in a multiconductor cable. Ignoring these effects results in large errors (~40%) in estimates of the magnitude of the field arising from a 1-kHz alternating current, but negligible error (at most, several tenths of a percent) in the magnitude of the field due to currents at power-line frequencies (50–60 Hz). We conclude that ignoring proximity effects in noncontact electric power sensing will not significantly affect the load current estimates obtained from existing US Army Combat Capabilities Development Command Army Research Laboratory methods—except in the case of nonlinear switching loads such as DC power supplies, which can generate significant harmonics in the 1-kHz range.