Motor efficiency and motor health conditions
Release date:
2025-07-16
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Abstract
In recent years, given the relatively high power consumption of electric motors, manufacturers have invested significant efforts in designing more efficient induction motors. However, one factor that significantly impacts motor efficiency is often overlooked. Typically, industrial motors operate with efficiencies ranging from 50% to 85%. Moreover, poor motor health can lead to a substantial drop in energy efficiency. The rated efficiency values provided by manufacturers are only accurate when the motor is running under ideal conditions—specifically, when there are no noticeable abnormalities, defects, or malfunctions during operation. If a machine experiences even early-stage faults, the motor’s efficiency will inevitably decline.
It is well known that motor efficiency refers to the ratio of a motor's useful power output to its total power input. Figure 1 illustrates the process by which electrical energy is converted into mechanical energy, along with the associated energy losses, including intrinsic power losses and abnormal power losses. Formula 1 calculates the motor efficiency:
► Intrinsic Power Loss
These include copper losses (resistance, skin effect), iron losses (eddy currents, hysteresis), and mechanical losses (friction, wind resistance). Intrinsic power losses can be minimized during the motor design phase.
► Abnormal Power Loss
This includes additional power losses caused by motor conditions that are less than optimal, such as any one or more of the motor faults listed in Table 1. By ensuring the motor operates at its best possible condition, abnormal power losses can be minimized— a goal that is closely tied to the motor’s maintenance plan.
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