What happens to a motor when it decelerates?

When a motor decelerates, it can actually increase the fault current. This occurs because as the speed of the motor decreases, the back electromotive force (back EMF) that opposes the supply voltage also reduces. As the back EMF decreases, the motor draws more current from the supply, which can lead to a temporary surge in current levels, specifically if there are any faults present in the motor or its circuit.

Deceleration may be caused by external loading, inefficiencies, or intentional braking. During this process, if the motor experiences a rotor failure or a short circuit condition, the increased current can result in a higher fault current. This phenomenon is significant in understanding motor protection and system stability, making it crucial for those who work with electric motors to grasp these dynamics.

The other options present scenarios that do not align with the typical behavior of a motor during deceleration, thereby highlighting the unique aspect of fault current increase as a direct consequence of reduced speed and back EMF.