Simplified expressions for the evaluation of the cyclic ratings of low and medium voltage cables in non sinusoidal conditions

Abstract

The paper proposes a procedure which allows to known, for assigned harmonic profile of nonlinear loads, the cable cyclic ratings in non sinusoidal operating conditions. The proposed procedure employs simplified expressions very similar to those adopted by IEC Standard in sinusoidal conditions, being the harmonic presence taken into account by a new proper definition of the load-loss factor and by the introduction of harmonic coefficients easily available. Numerical applications to low voltage and medium voltage cables are developed and discussed. The conclusion is that it is more needed to take into account the harmonic presence in the evaluation of cable cyclic rating than when dealing with 100% load factor.