ABB PSTX30 Installation And Commissioning Manual page 72

7.2.1 Torque start ramp
When the softstarter is given a start signal, the softstarter
makes a quick ramp to set Start ramp initital level. Then
the softstarter controls the output voltage so that the
output torque will follow a predefined optimal torque curve
during pre-set time to 100 % nominal torque.
When the output voltage reaches 100 % nominal voltage
(Top of ramp), the softstarter closes the by-pass.
To reach Top of ramp the following conditions need to be
met:
• The output voltage reaches 100 % nominal voltage.
• The current is below 1.2 x nominal motor current.
The time between the start signal and when nominal
torque is reached is the start ramp time.
The start ramp time can be longer depending on if the
motor is to start with a very heavy load.
Exampel: If the Start ramp time is set to 2 seconds and the
motor is supposed to start with a heavy load. This can cause
that the output current does not go below set 120% of nominal
motor current when the pre-set start rampt time is reached.
Torque start ramp is configured with the following
parameters:
7
Parameter
02.01 Start mode
02.03 Start ramp Initial level
02.04 Start ramp time
03.05 Torque limit level
28.06 Torque profile start
28.07 Torque finish
28.08 Torque tune
28.09 Torque ctrl gain
28.10 Torque PI intergration time
28.11 Torque slip
28.12 Torque diff
28.13 Torque filter time
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Description
Set to Torque ramp.
Sets the torque level from where the start ramp
initiates.
Sets the time it takes for the voltage to reach 100%.
Sets the limit for the torque during soft start with torque
control.
Sets the shape of the torque ramp during start.
• Constant setpoint is for centrifuge
• Linear is for compressor
• High inertia pump is for long conveyor belts
• Progressive curve is for centrifugal pump
Sets the operational torque for Torque start ramp
setting in percentage of base torque.
Sets the adjustment of resistive losses.
Sets the speed of the voltage regulator during torque
start and stop. It seldom needs to be changed, but if
a dip occur in the torque curve during stop, increasing
this value might solve it.
Sets the integration time of PI controller.
Sets the slip difference from nominal to pull-out torque
in percentage.
Sets the maximum desired difference between
reference and actual torque in percentage.
Sets the Torque control filter time in seconds.
Setting range Default value
Voltage ramp, Voltage ramp
Torque ramp,
Full voltage start
10 ... 99% 30%
1 ... 120s 10s
20...200% 150%
Constant Linear ramp
setpoint,
Linear ramp,
Progressive
curve, High
inertia curve
30...500% 100%
0...1000% 100%
0.01 ... 10 0.04
0.001 ... 10 s 0.002 s
0.1 ... 100 % 1.0 %
0.1 ... 100 % 2.0 %
0.01 ... 10 s 0.02 s