Speed-torque characteristic curve

The speed-torque characteristic curve looks as follows:

Characteristic curve 1:

Below 20 Hz, the drive cannot be loaded with the rated motor torque. The reduced speed decreases the self-cooling of the motor. As a result, the motor would heat up excessively.

This limit is not caused by the inverter. Motors with sufficient forced cooling can even be loaded with a nominal torque below 20 Hz.