counter-electromotive force

This opposing electric field is called "counter-electromotive force" (back EMF).

By adding rolls to the armature of a motor, a larger and larger counter-electromotive force is generated on the motor.

Almost all the techniques used against to cogging torque also reduce the motor counter-electromotive force and so reduce the resultant running torque.

Counter-electromotive force, CEMF).

The author states that the acceleration behavior of the machine is due to the consumption of torque from the induction motor, rather than any unconventional manipulation of Electromagnetic fields or Counter-electromotive force.

The counter-electromotive force (abbreviated counter EMF, or CEMF), also known as the back electromotive force, is the voltage, or electromotive force, that pushes against the current which induces it.

As the locomotive accelerates, the now-rotating motor armatures will start to generate a counter-electromotive force (back EMF, meaning the motors are also trying to act as generators), which will oppose the output of the main generator and cause traction motor current to decrease.