Antonov

The aim of this research is to enhance reliability of power grids with single-phase shielded cables by preventing transition from a single-phase fault to a line-to-line short circuit. Arc-flash processes during a single-phase fault and sheath failure were analyzed in this study. Maximum duration of single-phase faults and its dependence on the method of cable installation were determined. The results of the study are important for estimating failure effects of single-phase faults on cables, for reducing maintenance and restoration costs of cable network. A mathematical simulation of electromagnetic and heat transient processes in a single-phase fault point was carried out using ELCUT software. The accuracy of the model was proved by a number of laboratory experiments with arcing short circuits. It was established that a single-phase fault transforms into a line-to-line short circuit for several seconds in case of a triangle configuration of three single-phase shielded cables with no gap between them. In order to prevent this process it was recommended to apply single-phase shielded cables of 6 – 35 kV to grids with low-resistance neutral grounding and with fast single phase-to-earth faults.