Transient State Characterization of Asynchronous Motors in Modern Low-Voltage Electric Installations

Abstract

Low-voltage asynchronous motor is the most common load used in any industrial electric facility. Due to their robustness and reliability, the induction motors have a very large application spectrum and are to be found in a variety of power units. It is assumed that over 70% of total energy used in any electric utility is dedicated to the electric motor drive systems. The paper quantitatively studies the transient state of such motors, which occurs at their start-up. The waveforms characteristics of these inrush currents are predetermined mainly by solving the associated differential equations that describe the dynamic phenomena at their start-up. An experimental investigation on an induction motor of 4 kW is also carried out. Supplementary, different solutions for the energising of these low-voltage motors are presented highlighting their performances and limits. These methods are critically rated according to their mitigation ability of the power quality issues associated with the energizing process.