ABB PSTX30 Installation And Commissioning Manual page 71

7.2 Torque ramp
When using the Torque ramp, the output voltage is
controlled, so that the output torque will follow a
predefined optimal torque curve during start and stop
ramp.
For Torque start ramp there is four 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 start, the rotational
speed is constant if the set torque curve corresponds to
the actual load curve. The output voltage will not increase
linearly, as when using the voltage start ramp, see Figure
80.
The Torque ramp benefits the mechanical starting
behaviour of the equipment driven by the motor, to be
softer than when using the Voltage start ramp.
For Torque stop ramp there is one fixed torque curve. This
fixed torque curve is optmimized for pump applications.
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80
rpm
Start
U
Start
Figure 80: Torque start ramp
Time
Time
7