ABB PSTX Series Installation And Commissioning Manual page 78

7.3 Torque ramp
When using the Torque ramp, the Softstarter controls
the output voltage so that the output torque follows a
specified optimal torque curve during start and stop
ramp.
For Torque start ramp there are 4 different adjustable
torque curves. See description of torque profile
parameters for examples on when to use which curve.
The curves are:
• Constant
• Linear
• High inertia
• Progressive
When using the Torque start ramp, the acceleration is
constant if the set torque curve is the same as the actual
load curve. The output voltage does not increase linearly
like when using the voltage start ramp, see Figure 7.4 .
The Torque ramp makes the equipment that the motor
drives stop much softer than the Voltage start ramp.
For Torque stop ramp there is one fixed torque
curve. This fixed torque curve is optimized for pump
7
applications.
78 Functions | Installation and commissioning manual |
rpm
Start
U
Start
Figure 7.4
Torque start ramp
1SFC132081M0201
Time
Time