Effects of small and large induction motors on voltage sag profile

Voltage sags is a problem affecting the electrical qualities. In this paper, effects of small and large induction motors on voltage sag profile are compared and discussed. The study results show that as the fault is initiated, reactive power contribution from the large HP motor is more significant to prevent fast collapse of the voltage, resulting in non-rectangular shape of sag. The motor´s negative torque also induced during fault sag occurrence causes speed loss. The loss of speed of the large HP motor considerably requires much more current and reactive power to restore the internal emf, leading to a greater delay in voltage recovery.