A series-wound DC motor produces high starting torque. What happens to the current as speed increases?

In a series-wound DC motor, the field winding is connected in series with the armature winding. When the motor starts, a high current flows through the armature and the series field winding, producing a strong magnetic field and resulting in high starting torque.

As the motor speeds up, the back electromotive force (back EMF) generated by the motor increases. Back EMF opposes the applied voltage and effectively reduces the net voltage across the armature. Because the torque produced by the motor is proportional to the product of the armature current and the field strength, and since the field strength decreases as the speed increases, the current required to maintain the necessary torque decreases as well.

Thus, as speed increases, the armature current decreases to a point where it stabilizes at a lower level than at start-up. This relationship between speed and current in a series-wound DC motor is essential to understanding its performance characteristics across various operational conditions.