Speed range is the ratio of the output maximum frequency/minimum frequency where the nominal torque is available.

Example: For a 50Hz motor

Altivar 71 in open loop mode, speed range is to 1...100Hz with a nominal speed motor of 50 Hz.

1- 50/100=0.5 Hz and 50/1= 50 Hz

2- The torque curve is guaranty in the speed range of 0.5 Hz to 50 Hz