Effect of the neutral interruption on the unbalanced three-phase consumers

Abstract

Phenomena usually associated with neutral conductor interruption are sensitive issues of low voltage electrical networks. These phenomena are now directly related to the power quality, especially in the case of three-phase unbalance consumers supplied with low balanced/unlalanced three-phase system of voltages. Therefore a detailed analyse for assessment of the risk development of these events is required. The paper deals with an analytical description of the neutral conductor interruption effect on the unbalanced three-phase consumers. The simulations for three cases are considered: low voltage supply system with four conductors in normal conditions of operation; the case when the neutral conductor is interrupted in the substation area; the case when the neutral conductor is interrupted in the lines area. It is shown that the neutral displacement voltage and neutral current depend on the type of fault and on the severity of the three-phase consumer unbalance. The results are useful for appropriate designing of the protection system.