Study on the Reduction of Leading Power Factor During Load Variations and Standstill Operation of an Induction Motors

Induction motors are a common type of linear load, but due to their resistive and inductive components, the current phase lags behind the voltage phase, resulting in a low power factor. A low power factor increases the apparent power demand from the power source, necessitating the use of power factor compensation devices. These devices are typically designed based on the assumption that the motor operates at its rated output. However, when the motor runs at a reduced load, the power factor decreases, prompting the installation of compensation devices at the motor or on the secondary side of the transformer to improve the overall power factor of the system.<br/>Despite the presence of power factor correction devices, the power factor tends to drop as the load decreases. Additionally, when the motor is idle, such as during nighttime or holidays, residual reactive power may cause the power factor to shift to a leading condition. A leading power factor can lead to voltage rise, potentially impacting system stability.<br/>This study proposes a simple method to prevent power factor from becoming leading during periods of motor inactivity by interlocking the transformer when the motor is stopped.