Short circuit currents and thermal stability of single-phase cable shields in distribution networks

摘要

The numerical analysis of two-point short circuit currents in single-phase cable lines in distribution networks with low-resistance grounding is carried out. As an illustration, the influence of a cable line length and parallel cable laying on the distribution of currents in cable shields is considered and the maximum safe times of shield currents on the basis of thermal stability criteria are determined. It is shown that the electrical connection of cable shields in joint boxes allows to substantially increase the maximum safe times of shield currents provided the faults are considered to take place directly in cable joint boxes.