Voltage reflection, which can destroy a motor, may occur when the motor cable is longer than or equal to the critical length; lead lengths as short as 25 ft are sufficient for such an event . Thus, voltage reflection is a function of the lead length of the power cable between the drive and motor.
We can predict voltage reflection using the following equation:
Eq. 1: Lcritical=Vcable × tr
where, Lcritical is the critical cable length in feet.
Ive used more than 100 meters cables between VFDs and Motors !