Calculation Method of Current Rating for Overhead Insulated Cables

To address limitations of traditional calculation methods for current rating of overhead insulated cables, which ignored actual wind speed fluctuations and resulted in conservative calculation results, a transcendental equation for calculating surface temperature of overhead insulated cables was derived by referencing the calculation method for overhead bare conductors and combining it with the thermal resistance calculation method for traditional cable insulation layers. The equation was numerically solved using the Newton-Raphson method in Mathcad to calculate cable current rating, which was then compared with actual current rating. Results showed that the calculated current rating agreed well with the actual data, with a maximum error of only −2.96%, which verified feasibility of the proposed method. Comprehensively considering laying environmental factors such as wind speed and solar radiation, the calculation method allows flexible adjustments according to actual laying conditions, which could provide a reliable reference for current rating evaluation, engineering design, and safe operation of overhead insulated cables under complex operating conditions.