
Operating Characteristics of Induction Motors 179
N
s
Speed
Figure 6.3 Typical torque-speed curve showing two different loads which
have the same steady running speed
The speed-time curves for run-up are shown in Figure 6.4.
Note that the gradient of the speed-time curve (i.e. the
acceleration) is obtained by dividing the accelerating torque
0
Load B
Load A
can certainly be limited, but as far as torque per line amp is
concerned soft-start systems are no better than series reactor
systems, and not as good as the autotransformer and
star/delta methods.
RUN-UP AND STABLE OPERATING REGIONS
In addition to having sufficient torque to start the loa ...