Asynchronous or induction motors are commonly employed in industrial applications. Their precise accelerating or starting time is needed for setting their overcurrent protection devices against heating and for assessing power quality of electric utility distribution power system. The accelerating time is usually determined from a tedious time-domain dynamic simulation with commercial software tools, which basically require a full knowledge of the motor’s equivalent parameters. Often these parameters are not readily available to the end-users while other technical information is. Thus, this paper presents a novel analytical approach to calculate the motor accelerating time using standard technical data. The required speed-torque curve of induction motors is directly determined from the manufacturer-provided information, instead of requiring the conventional equivalent-circuit parameters. Accuracy of the proposed technique is validated by comparing the calculated accelerating times against those from time-domain dynamic simulations using a full fifth-order model of induction motor: the results mostly agree in a satisfactory manner.
