If you don't pay attention to cable charging current you may be in for a lot troubleshooting fun!  Remember that the cable going from the drive to the motor can require up to 1 amp of  "charging current" for every 100 feet.  When specifying a drive, you will need to allow an extra amp for each 100 feet of cable pull to the motor.  If you notice, most Allen Bradley drives are rated in amps now.  There is also a horse power rating, but it is more of a tool to help you zero in on the correct model.