Energy Consumption in Electric Motors Operating under Different Fault Conditions

Abstract

Electric motors are essential components of industrial systems and are extensively used in applications such as fans, pumps, compressors, and conveyors. As energy conversion devices, they typically operate with high rated efficiency, particularly in the case of medium- and high-power motors. However, the actual operating efficiency may be significantly reduced when motors are affected by faults or degradation mechanisms. Such faults introduce additional electrical, mechanical, and thermal losses, leading to increased energy consumption that is not converted into useful mechanical output. This paper presents an experimental investigation of the influence of different fault types on the efficiency of induction motors. Several representative fault conditions are examined, including broken rotor bars, stator asymmetries, misalignments and loosened bolts, cooling system deficiencies, and insulation degradation. For each fault scenario, efficiency curves are obtained under a wide range of load levels and fault severities using a controlled laboratory test bench. The experimental results demonstrate that all investigated faults lead to measurable efficiency reductions across the entire operating range, with increasingly pronounced effects as fault severity rises and as the motor operates near rated load conditions. These findings confirm that motor faults impact not only operational reliability but also energy efficiency, often resulting in hidden energy losses during prolonged operation. Consequently, the study highlights the importance of condition monitoring and maintenance strategies as effective tools for preventing failures and ensuring energy-efficient operation of industrial electric motors.