Relating stator current Concordia patterns to induction motor operational abnormalities

With industrial growth it has become necessary to monitor the condition of three phase squirrel cage induction motor, as it is the most sensitive part in the production line of industry. Special attention has been given to non-invasive methods which are capable of detecting fault by acquiring major data without disassembling the machine. The present paper discusses a few basic yet important aspects of condition monitoring of the induction motor based on investigation of Concordia patterns obtained through the Park´s transformation of stator currents. The current Concordia pattern is greatly influenced by the internal condition of the motor as well as the external supply condition. The prime focus of the diagnostic technique is on identifying the change in shape of current Concordia patterns and shifting of its major axis orientation corresponding to stator inter-turn fault conditions with varying severity and varying power quality problems of supply system, like voltage sag and swell. This proposed method can be efficiently employed to discriminate and assess the operating condition of induction motor due to internal stator winding fault and power quality problems of the external supply system.