Calculation of ampacity of single-core cables with sheath circulating current based on iterative method

Based on the thermal field of single-core cables, both ampacity with or without the circulating current in cable sheath are calculated by iterative method in VB programmer, and the result is compared with IEC-60287 to prove the correctness of this method. The influence of circulating current in the cable sheath to its ampacity is discussed here, the relationship curve of one cable ampacity changing with another adjacent circuit current is also given in the paper. (4 pages)