Method of assessment and prediction of overvoltage caused by single-phase arc ground short circuits in the 6–10 kV mains, as a way of increasing the electrical safety level in mining facilities

Abstract

Introduction. Overvoltage caused by single-phase ground short circuits are the main reason of multiple breakdowns of insulation. Assessment and forecast of overvoltage in SPGSC in the 6–10 kV mains is therefore a relevant task, and the solution to this problem will make it possible to select effective methods and means of limiting overvoltage and improve the conditions of electrical safety. Research aim is to improve the methods of assessing and forecasting overvoltage of arch SPGSC in the 6–10 kV mains of mining facilities. Methodology. This article provides analysis of current hypothesis and methods for the assessment of overvoltages in the single-phase ground short circuit (SPGSC) mode. Currently the hypothesis of Peterson, Peters–Slepyan, Belyakov–Djuvarl does not fully reflect the factors that affect the maximum overvoltage emergence of the single-phase arc ground short circuits in the 6–10 kV mains, because they don’t take into account the capacitive current value of SPGSC, arc combustion conditions, lifetime of SPGSC, inductance of engines and transformers. Results. There have been obtained dependences that show the dependences of frequency with which overvoltage happens from the factors that were mentioned above. The shown dependences can be used for calculation and assessment of overvoltage in the 6–10 kV mains with different neutral modes to justify the need for activities that will protect electrical systems, transformers, electrical engines from overvoltage in the SPGSC mode and considering its lifecycle. Summary. It was established that from the electrical safety positions of 6–10 kV mains with resistive or combined modes of neutrals on mining and extractive facilities create conditions for the safer exploitation of technological complexes, facilities and electrical equipment, because it can reduce maximum overvoltage ratios by half and thus reduce the number of repeated breakdown of insulation in the SPGSC mode.