Assessment of zero-sequence voltage influence on safety indicators during single-phase faults in low-voltage ship electrical networks

Abstract

One of the trends in the development of marine technology is the constant increase in the degree of electrification of ships. This process is accompanied by an increase in the danger of ship electrical networks, determined primarily by the operation of electrical installations with single-phase insulation damage. The consequences of this mode largely depend on the phase capacity of the electrical network. Moreover, the influence of phase capacitance on the danger of single-phase short circuits is determined not only by its size, but also by the degree of asymmetry. It is proved that it is precisely the asymmetry of the phase capacitances that causes the formation of zero-sequence voltage in ship electrical networks. An analysis of the indicators of the main dangers of the electrical network was carried out, taking into account the influence of zero-sequence voltage on them. It is proved that in electrical networks with an isolated neutral, the response time of the protection to cut off single-phase contact currents must be selected taking into account the fact that on-board networks may have asymmetrical phase capacitances. A set of theoretical and experimental studies was carried out to assess the influence of zero-sequence voltage on quantitative indicators of the danger of a ship's electrical network. An experimental assessment of the influence of phase capacitance asymmetry on the stability of electrical discharges during single-phase faults in electrical networks with an isolated neutral was carried out. It has been demonstrated that during short circuits through an unstable electric discharge, the presence of a zero-sequence voltage leads to a significant increase in explosion and fire hazard indicators of the electrical network, such as power and energy released at the site of insulation damage. It was revealed that increased safety can be achieved by influencing the voltage on the neutral.