What will be the impact of undervoltage and overvoltage on induction motors?

An overvoltage in an induction motor will cause the reactive component of the current inside to increase causing eddy current heating of the rotor and stress on the insulation.

In the case of an undervoltage, the low voltage causes the torque developed to reduce. This results in an increase of slip and a reduction in speed. The motor tries to reduce the slip by drawing more current. This overloads the motor and can cause overheating.