What effect does counter EMF have as an induction motor accelerates?

As an induction motor accelerates, the phenomenon of counter electromotive force (EMF) comes into play. Counter EMF is generated within the motor as it begins to spin and develop its magnetic field. The primary effect of this counter EMF is that it opposes the applied voltage, thereby reducing the overall voltage that is effective in driving current through the stator windings.

As the motor speeds up, the magnitude of the counter EMF increases. This results in a decrease in the current drawn from the power supply because the effective voltage available to overcome the impedance in the stator is reduced. Consequently, since the current is directly related to the torque produced by the motor, the increasing counter EMF leads to a decrease in current, which is essential for the safe and efficient operation of the motor.

This relationship between counter EMF and current is a fundamental principle in the operation of AC motors, showcasing how they regulate their power consumption as they reach their operating speed.