Application of Thermal Resistance Dynamic Characteristics on High-Voltage Cable Ampacity Based on Field Circuit Coupling Method

Abstract

IEC60287 standard is a common cable ampacity calculation method. Thermal resistance value of each layer of cable is defined as a constant in IEC standard. But in fact, thermal resistance is affected by many factors and cannot be maintained as a constant value in long-term operation. This will bring error to the calculation of the cable ampacity. Therefore, this paper proposes an ampacity calculation method by using finite element method to study thermal resistance dynamic characteristics and combining the thermal model to modify thermal resistance of high voltage cable with the ideas of field circuit coupling method. This paper uses measured temperature data of a cable to verify the field circuit coupling method. Results show that the calculation error of the method is less than 6%, which is 30.5% lower than using IEC standard. At the end of the paper, the field circuit coupling method is applied to cables with common cross sections. Results show that compared with IEC standard, the error of the calculation results of the field circuit coupling method is reduced by more than 19%, which indicates that the method can calculate the cable current more accurately.