ABB PSTX Series Installation And Commissioning Manual page 79

7.3.1 Torque start ramp
When the Softstarter receives a start signal, the
Softstarter makes a quick ramp to set Start ramp initial
level. Then the Softstarter controls the output voltage so
that the output torque follows a specified optimal torque
curve during pre-set time to 100% nominal torque.
When the output voltage comes at 100% nominal voltage
(Top of ramp), the Softstarter closes the bypass.
To come at Top of ramp these conditions need to be met:
• The output voltage comes at 100% nominal voltage.
• The current is below 1.2 × 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 if the motor starts with
a very heavy load.
Example: If the Start ramp time is set to 2 seconds
and the motor starts 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 ramp time is
reached.
Configuration of the Torque start ramp with these
parameters:
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 integration time
28.11 Torque slip
28.12 Torque diff
28.13 Torque filter time
Description
Set to Torque ramp.
Sets the torque level from where the start ramp
initiates.
Sets the time it takes for the voltage to come at 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 curve is for long conveyor belts
• Progressive curve is for centrifugal pump
Sets the operation torque for Torque start ramp setting
in percentage of base torque.
Sets the integration time of PI controller.
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.
1SFC132081M0201
Setting range
Voltage ramp,
Torque ramp,
Full voltage start
10 ... 99%
1 ... 120 s
20 ... 200%
Constant
setpoint,
Linear ramp,
Progressive
curve, High
inertia curve
30 ... 500%
0 ... 1000%
0.01 ... 10
0.001 ... 10 s
0.1 ... 100%
0.1 ... 100%
0.01 ... 10 s
| Installation and commissioning manual | Functions
7
Default
value
Voltage
ramp
30%
10 s
150%
Linear ramp
100%
100%
0.02
0.004 s
1.0%
2.0%
0.02 s
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