Controlled Starting of AC Induction Motors

As the demand for electrical energy continues to increase, increasing restrictions will be placed on full-voltage starting of ac induction motors. Inrush is the problem. The utilities are tending to enforce more rigorously the historical limits on the amount of inrush allowed. Reduced-voltage starters have traditionally been used to reduce the impact of motor starting inrush. All traditional starters have reduced the amount of inrush, but none have eliminated it. The type of driven load must be taken into consideration in order to provide motor torque sufficient to start the load while eliminating the starting current inrush. The Ultra Torq is a motor plus solid-state starter combination which provides a solution to the problem. The Ultra Torq controls the rate-of-change of kVA with respect to time, thereby eliminating the problem of inrush. A successful start is assured by matching the motor, starter, and controller to the torque requirements of the load and to the kVA limits of the system. The match makes the difference.