GENERALISED CHART, LOAD ANGLE, AND STABILITY LIMIT IN INDUCTION MOTORS

ABSTRACT A generalised torque chart is presented in which the torque is related to the torque-angle in induction motors. Together with iso-slip lines, the chart is quite helpful in determining motor performance. Using the mentioned chart, the transient performance of induction motor is predicted using simple and straight-forward method. The new method uses the load angle as the variable of interest. The approach is limited to the prediction of the transients following sudden load or voltage changes when the motor is running at steady state. The derived equation is a second-order non-linear, differential equation which is solved by numerical techniques. A considerable saving in computation time is achieved, when compared to that used in solving the same problem using the Generalised Machine Theory (Two-Axes Theory). The analysis is thought useful in power system stability studies.