Influence of Cable and Twist Pitch Interactions on Eddy Currents In Multifilamentary Strands Calculated Using an Anisotropic Continuum Model

We have calculated the eddy current loss in multifilamentary strands wound into helical geometries (round cable geometry) as a function of the cable pitch (Lcab) twist pitch (Lp), and cable radius (Rc). Previous calculations of this interaction concentrated on modifications of the mutual inductance, finding a loss minimum at Lcab = Lp. However, our calculations show that the effective coupling lengths will be enhanced near Lp = Leff (≈ Lcab for Lcab > 2πRc, the loss maximum occurs for Lp ≈ Lcab, only if Lp and Lcab are of opposite helicity.