Starting Capacitor Motor

At the exact moment of the velocity intervals, the main winding properly isolated becomes capable of developing almost the same torque as the combined windings. For higher speeds, which can range from 80% to 90% of the synchronous speed, the torque curve with the combined windings must cross the torque curve of the main winding so that at high speeds the motor will develop a smaller torque for any with the auxiliary circuit activated. Because the cross curves do not always occur at the same point and the centrifugal circuit breaker does not always have the ability to open at the same speed, it is common to make the opening take place a few moments before the curves intersect.

Thus, the starting capacitor motor, refers to a machine relatively similar to the split-phase machine. The main difference between them is the insertion of an electrolytic capacitor in series with the starting auxiliary winding. The capacitor allows a greater angle of lag between the main and auxiliary winding currents, providing high starting torques. It should be noted that in the split-phase motor the auxiliary circuit is deactivated at the exact moment when the motor reaches approximately 70% of the synchronous speed.