Practical Power Quality Charts for Motor Starting Assessment

The impact of motor starting on power quality can be assessed using detailed computer simulation studies. However, not every motor installation case needs such an extensive assessment. Utility planners are interested in quick evaluation of the potential impact of a motor installation proposal. Based on the findings, they can then determine if detailed case studies and what types of case studies are necessary. This paper presents three charts for motor starting planning according to three power quality concerns. These concerns are the amount of voltage drop caused by motor starting, the compliance to the ITIC curve, and the compliance to the IEC flicker meter limits. These charts can help utility planers to conduct quick and first-cut assessment of a motor starting situation. They also reveal the key factors affecting the motor starting related power quality concerns. The principles behind these charts are explained. Examples are given to show how to use them for quick assessment of motor starting impact.