Cyclic and emergency rating factors of distribution cables in presence of nonlinear loads

The paper proposes procedures which allow to know, for assigned harmonic profile of nonlinear loads, the cable cyclic and emergency ratings in nonsinusoidal operating conditions. The proposed procedures refer to distribution cables and employ simplified expressions very similar to those adopted by IEC Standard 853 for the sinusoidal conditions; the harmonic presence is taken into account by a new proper definition of the load-loss factor and by the introduction of harmonic coefficients easily to be predicted. Numerical applications to low voltage and medium voltage cables are developed and discussed considering typical nonlinear load scenarios, in order to furnish practical indications regarding the derating factors to be introduced for the harmonic presence.