Siemens Midimaster Eco Reference Manual page 10

ECO REFERENCE MANUAL
Torque
0
Torque Reduction above Base Speed
Therefore in order to control the speed of a
standard AC motor, the applied frequency and
voltage must be controlled.
The use of a standard induction motor together
with a variable frequency speed controller allows
a cost effective speed control system to be built.
0.5 1.0
Flux, voltage
Torque capability
1.2 1.5 Speed (X 50/60)
3-3