기동중 단상 결상시 3상 유도전동기의 동작 특성에 관한 연구

Abstract

Induction motors cause a failure due to electrical and mechanical causes. The most significant cause of electrical failure is due to overheating due to high current. Induction motors generate high currents at start-up, but become very low as the rotational speed increases. If the current does not decrease as the rotational speed increases, it may act as an electrical stress on the winding. A single-phasing in which one phase of the three phases is suddenly opened. The generation of single-phasing can overheat the stator winding due to a sudden increase in current, if this condition persists, the winding will overheat and eventually be burned out. Further, since the rotational speed is transferred to the braking region and the rotor is restrained, the normal torque can not be ensured. Therefore, it is very important to analyze what problems occur when single-phasing exists in an induction motor.BR In this study, we analyzed the magnitude and the torque change of voltage, current, power, power factor appearing to the induction motor when single-phasing occurred from three phase power source during startup. As a result of the analysis, it was found that the current generated during single-phasing is higher than the normal start-up current, and if it is not removed, it may persist and lead to overheating. And it can be seen that normal torque can not be secured because the forward torque and the reverse torque are repeatedly operated by the restraint of the rotor.