Analytical voltage drop calculations during direct on line motor starting: Solutions for industrial plants

Abstract

Electrical motors in modern industrial systems are becoming larger due to the requirements of heavy application. Some electric motors are considered large even when compared to the total load capacity of the industrial plant. Starting electrical motors can cause severe disturbances to the motor, other locally connected loads, and also buses electrically remote from the point of motor starting. Ideally, a motor starting study should be made before a large motor is connected to an industrial electrical system to take proper remedial solutions when necessary. The static and dynamic analyses are used to study the effect of electric motor characteristics on the industrial power system. The most well-known and studied effect of motor starting is the voltage drop experienced throughout an industrial power system directly resulting from starting large motors. In this study, the effect of voltage fluctuation on the power system has been evaluated, voltage drop during motor starting is formulated, and applied to the industrial electrical system using motor ratings and previously calculated short circuit power. Although there are various computer-aided studies for motor starting, this study will benefit those who require simplified and accurate voltage drop checking during motor starting by using an available and reachable motor, transformer, and calculated short circuit power. In order to verify the applicability of the theoretical formulation, containing's motor, transformer, the calculated short circuit power of the distribution network, the percentage voltage drops over the fifteen different operation modes have been calculated for an industrial plant in the numerical study. (C) 2021 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Ain Shams University