Induction motor transient response to multiple faults in unbalanced power systems

Abstract

Although the effects of an unbalanced supply on overheating induction motors have been known for some time, little or no attention has been paid to the dynamic response of such a system. A recent investigation though has evaluated the effects of an unbalanced distribution system, unbalanced single-phase loads, unbalanced shunt faults, and series faults (open conductor) on the transient behavior of a three-phase induction motor. This paper extends that work to the case of motor transient response due to multiple asymmetrical faults in an unbalanced power system. The paper investigates the dynamic behavior of an induction motor connected to an unbalanced three-phase power system subjected to a shunt fault at one location and blown fuses or open conductor at another location. The method involves phase frame representation of the line. A significant finding is that certain multiple faults cause the induction motor to lose stability.