FEATURES OF THE INFLUENCE OF A SHORT CIRCUIT OF THE STATOR WINDING OF AN INDUCTION MOTOR ON THE SPECTRAL COMPOSITION OF ITS STATOR CURRENT

In recent decades, there has been a consistent trend towards the increasing role of automated electric drives based on induction motors. This is driven by objective factors, such as the development of high-precision mathematical models of induction motors, which have improved the accuracy and functionality of their control systems, as well as advancements in power semiconductor technologies that have enhanced efficiency and reduced the cost of frequency converters. These advancements in scientific and technical progress have led to an expansion of the application of induction motors in controlled electric drives under difficult starting conditions, which were traditionally implemented using direct current motors, as well as an increase in the number of electric drives with electric control types. At the same time, modern technological progress has also resulted in increased complexity, cost, and technological demands of industrial equipment, which raises potential risks of emergency failures. Another common trend for Ukraine and many industrially developed countries is the growing number of electrical equipment that has reached the end of its nominal service life. Since there is an inverse relationship between the reliability and operating time of rotating electrical machines, this logically leads to an increased need for effective diagnostic systems. The article theoretically proves the influence of interturn short circuits in the stator windings of an induction motor on the shape of its stator currents. It is shown that this diagnostic method has a sufficient degree of expressiveness, allowing for a high probability of identifying this type of defect among other types of damage to the induction electric machine. The justification for using the amplitude of the fundamental harmonic f1 for diagnosing this type of defect is provided, along with the subsequent modulation of even harmonics at frequencies of 2f1 to 10f1. It is proposed to consider the current spectrum in a logarithmic scale of dB/Hz due to the presence of a dominant current component at the power supply frequency f1.