Abstract: This paper presents mathematical model for determination of reduction factor of aerial bundled cables. Knowledge of reduction factor of aerial bundled cables, that supplies a substation, is important for substation grounding design as well as for right estimation of safety conditions. Reduction factors of frequently used aerial bundled cables are determined by presented mathematical model. Influence of metal screen temperature as well as influence of supporting wire characteristics on reduction factor value are shown.
Keywords: Reduction factor, aerial bundled cable, single line to ground fault, impedance.