Abstract: A motor voltage control device for single-phase and for three-phase motors, for controlling the voltage supplied to the motor to thereby decrease power when the motor is less than fully loaded. The single-phase device includes a soft start unit and fail detect unit. The three-phase device includes a soft start unit, a fail detect unit, and further provides for controlling motor voltage by allowing modifications to only the positive half cycle of the motor voltage. The three-phase device also continually insures and provides for a path for negative flowing motor currents. The three-phase device also provides for a logic ground for its logic circuitry. The three-phase device may be used with three-phase motors that do not have an easily accessible fourth lead to an internal ground connection.