Rockwell Automation 150 MNL/SMC DIALOG+/APP-PROD GUIDE - Manual (Page 165)

Reference 10-3
The following graph illustrates a typical speed-torque curve for a
NEMA Design B induction motor. An understanding of several
points on this curve will aid in properly applying motors.
Figure 10.2 Speed Torque Curv
Locked-Rotor Torque (LRT)
Locked-rotor torque is the torque which the motor will develop at rest
for all angular positions of the rotor, with rated voltage at rated
frequency applied. It is sometimes known as “starting torque” and is
usually measured as a percentage of full-load torque.
Pull-Up Torque (PUT)
Pull-up torque of an induction motor is the minimum torqu
developed during the period of acceleration from locked rotor to the
speed at which breakdown torque occurs. For motors that do not have
definite breakdown torque (such as NEMA Design D), pull-up torque
is the minimum torque developed, up to rated full-load speed, and is
usually expressed as a percentage of full-load torque.
Breakdown Torque (BT)
The breakdown torque of an induction motor is the maximum torque
the motor will develop with rated voltage applied, at rated frequency,
without an abrupt drop in speed. Breakdown torque is usually
expressed as a percentage of full-load torque.
%
of
Full
Load
Torque
Pull Up Torque - PUT
Locked Rotor Torque - LRT
Breakdown Torque - BT
Synchronous Speed
Slip
Full Load Torque - FLT
Full Speed