Allen-Bradley SMC-50, User Manual

Page: 17 / 292

Rockwell Automation Publication 1560F-UM001A-EN-P - June 2019 17
Product Overview Chapter 1
Torque Control Start
This method provides a torque ramp from a user-adjustable, initial motor starting
torque to a user-adjustable, maximum torque over the defined starting ramp time.
The torque control mode provides a more linear starting ramp than a soft start,
potentially resulting in less stress on mechanical components and a more time
controlled ramp. A current limit value is also available to limit the starting
current throughout the torque start.
Figure 3 - Torque Control Start Timing Diagram
Current Limit Start
(1)
This method provides a current limit controlled start by maintaining a constant
current to the motor and is used when it is necessary to limit the maximum
starting current. The starting current and current limit starting ramp time is user-
adjustable. Current Limit Start can also be used in conjunction with Soft Start,
Torque Control, and Linear Speed Acceleration Starts.
Figure 4 - Current Limit Start Timing Diagram
(1) Kickstart is also available with Current Limit Start and Dual Ramp Start.
Current Limit
Time (seconds)
Start Run Soft Stop
Ramp Time
Torque
Ramp
Max. Motor Torque
%
Ra
te
d Mo
to
r T
or
que
100%
Starting
Torque
%
Full
Lo
ad
Curr
en
t
50%
600%
Current Limit
Time (seconds)
Start