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3–9
Figure 3.3.2.1: Torque/Speed Curve – Induction Motor
Figure 3.3.2.2: Torque/Speed Curve – Coupled Load
Each load coupled to an induction motor has its own speed/torque curve:
Figure 3.3.2.3: Torque/Speed Curve – Accelerating Torque
The acceleration of a motor-load system is caused by the difference between the developed torque
(motor) and the absorbed torque (load), and is shown by the shaded area in the next figure:
0 SPEED S
Locked Rotor Torque
( LRT, M
A
)
Pull Out Torque ( M
K
)
Pull-up Torque
Full Load Torque ( FLT, M
N
)
Synchronous speed
Figure 3.3.2.3
Torque/Speed Curve – Accelerating Torque
TORQUE
Pull Out Torque ( M
K
)
TORQUE
Pull-up Torque
Full Load Torque ( FLT, M
N
)
Synchronous speed
0 SPEED S
Figure 3.3.2.2
Torque/Speed Curve – Coupled Load
Locked Rotor Torque
( LRT, M
A
)
Pull Out Torque ( M
K
)
TORQUE
Full Load Torque ( FLT, M
A
)
Pull-up Torque
Synchronous speed
Figure 3.3.2.1
Torque/Speed Curve – Induction Motor
Locked Rotor Torque
( LRT, M
A
)
0 SPEED S
Chapter 3: Applications
SR44 Series Soft Starter User Manual
1st Ed, Rev B 07/31/2019