Electrical Safety Assessment in Distribution Networks Considering The Cable Conducting Sheaths Currents

Abstract

The use of low-resistance neutral grounding increases the stress voltage of grounded elements of transformer substation equipment. If the stress voltage is calculated while accounting for the spreading of single-phase earth-fault currents through conductive sheaths and cable shields, then the threshold limit values of capacitive currents will be higher than the values if assumed that the current only spreads through the grounding device of a single substation. The purpose of this study was to estimate the threshold limit values of capacitive current in distribution networks with low-resistance neutral grounding for stress voltage. Stress voltage was determined by the voltage on the ground loop with a resistance of grounding devices 0.5 Ohm. Values of voltages for different distances of earth faults from power centers and capacitive currents were obtained from 200 to 1000 A.