ANALYSIS OF THE COMBINED INFLUENCE OF POWER QUALITY PARAMETERS ON THE PERFORMANCE CHARACTERISTICS OF AN INDUCTION MOTOR
Abstract
This paper presents the results of experimental and theoretical studies on the combined influence of power quality parameters—voltage unbalance and waveform distortion- on the performance characteristics of an induction motor (IM) with a squirrel-cage rotor. The study is highly relevant in the context of modern power systems, where power quality issues are often underestimated, leading to violations of electromagnetic compatibility (EMC) within electrical networks.
To achieve the research objectives, a dedicated experimental setup was developed, allowing artificial variation of voltage symmetry and harmonic content. The analysis was performed under various motor loading conditions (load factor Kz = 0; 0.5; 1). The parameters measured included: phase power, torque, rotational speed, efficiency (η), and phase currents. The Box-Wilson method was applied to construct regression models describing the dependence of the main IM characteristics (speed n2, torque M, and efficiency η) on the voltage unbalance coefficient (K2U) and the total harmonic distortion coefficient (KU).
The results showed that even slight unbalance can significantly impact motor heating and insulation lifespan. The presence of higher-order harmonics, particularly the 5th and 7th, reduces the power factor by up to 25% compared to sinusoidal operation. Exceeding the allowable levels of harmonic distortion, as specified by GOST 13109-97, leads to a risk of insulation ionization and degradation. However, within the standard limits, harmonics have a negligible effect on the mechanical parameters of the motor.
The study also revealed that motor characteristics cannot be universally standardized across different types of induction machines, as they depend on both the motor design and loading conditions. This underscores the need for a comprehensive approach to power quality analysis that considers the cumulative effects of multiple factors.
Keywords: induction motor, power quality, voltage unbalance, waveform distortion, higher-order harmonics, efficiency, electromagnetic compatibility.
Downloads
