Transient Modeling of Calculation Temperatures of Single-Core Cables

Electrical cables are widely used in urban electrical transmission. It is necessary to monitor whether it operate normally or not. The conductor temperature is a key parameter should be monitored. However the conductor temperature of underground cables is very hard to measure for technical difficulties, the other option is calculation. The conductor temperature is associated with the temperature and thermal resistivity of material surrounded (e.g. soil), which is diverse with season and its water content and make the calculation complicated and inaccurate. To avoid the effect of soil on the calculation, the transient thermal models of a single-core cable are set in this paper; temperatures of conductor and metal sheath are calculated based on the detected temperature of outer jacket, and Runge-Kutta method is used to solve differential equations. An emergency temperature rising test was undertaken, which confirms the correctness and accurateness of the calculation of cable temperatures.