Importance of unbalance supply estimation for power quality assessment and power system reliability

This paper bestows the importance of reliable power system for proficient performance of industrial loads. As power quality is accountable for a reliable power system, therefore in this paper the power quality deteriorating aspects has been critically reviewed. While, unbalance in supply is one of the vital aspect for power quality worsening which inturn affect the performance of industrial loads. Various upshots of unbalanced supply on the performance of three-phase induction motor (3-Φ IM) has been analysed. It has been notified that derating of 3-Φ IM under unbalanced supply is a degree of unbalance dependent parameter as given by National Equipment Manufacturer´s Association (NEMA) definition. The shortfall of NEMA definition has been highlighted and it is asserted that degree of unbalance namely voltage unbalance factor (VUF) along with the condition of unbalance i.e. undervoltage or overvoltage is required for the precise assessment of 3-Φ IM operate under unbalance supply. As slip namely, `s´, is independent of VUF, able to quantify the condition of unbalance and easily measured in field. Hence, `s´, can be considered as apposite index for the specific assessment of derating of machine.