Methodology for Calculating the Real Service Life of 10 kV Cable Insulation by Determining the Parameters of Thermal Conditions in Various Operation Modes

This work presents a methodology for calculating the thermal modes of operation of 10 kV cable lines (CL) at different operating conditions and types of insulation. As a result, formal dependencies are shown, which clarify the parameters of the CL, considering their operation and temperature. The results are useful, reducing the number of emergencies and decreasing the probability of thermal breakdown. The results allow a more accurate selection of CL parameters at the design stage. Methods for calculating the temperature parameters and the service life of the CL, methods of statistical data processing, and methods for approximation functions, were applied. The ELCUT software package is used to visualize the results. The results concern the temperature parameters of 10 kV CL with paper-impregnated insulation (BPI), polyvinyl chloride plastic insulation (PVC) and polyethylene insulation (PE), placed in the air, in the ground, and in the pipe, considering the load factor (lf) of cables. The results of calculations of the service life of the CL are shown. The optimal lf of the CL is determined, considering the rate of thermal aging of insulation.