Research on Power Factor Compensation According to Load Changes in Low-Voltage Induction Motors

Induction motors are the most widely used rotating devices to obtain rotational power in industrial and commercial facilities. Induction motors are inductive loads and have a low power factor. Although this induction motor is sometimes used to drive a load with rated output, it is often operated at an output lower than the rated output. The reactive power used to compensate for the power factor of this induction motor is calculated based on the rated output, but in reality, the reactive power is insufficient at loads lower than the rating. Because it is difficult to select reactive power according to load fluctuations, domestic standards recommend the size of the capacitor for reactive power compensation according to the voltage and capacity of the induction motor. In reactive power compensation, there are two methods: installing a capacitor for each load and installing all of them in a bundle. In lump compensation, the size of reactive power is applied differently depending on the capacity of the transformer. In this study, we selected several low-voltage induction motors and analyzed how the power factor changes according to the change in power according to the change in load for individual compensation and lump compensation. As a result of the analysis, it was confirmed that at 1/2 load, the power factor required by the power company was not satisfied even if a power factor correction device was installed. Copyright © The Korean Institute of Electrical Engineers.