Installation Manual

Functions
Chapter 10
133
1SFC132003M0201
10:3 Stop mode
Path in menu:
Menu/SETTINGS/Functional Settings/
Torque control/ Stop Mode
Using the PST softstarter it is possible to choose between
two different types of stop ramps. These are voltage ramp
and torque ramp.
Voltage ramp When using the voltage ramp, the voltage
is decreased linearly from full voltage to
the end voltage during stop. Since the
torque depends on both the voltage and
the current, the torque curve does not
always follow the voltage curve. This has
the effect that the torque curve will not
increase or decrease linearly.
Torque ramp When using the torque ramp, the output
voltage to the motor is controlled so that
the torque will follow a predefined optimal
curve from full voltage to end voltage
during stop. This has the benefit that the
mechanical stopping behavior of the
equipment driven by the motor will be
much softer than when using voltage
ramp. This can be especially useful in
pump applications where a sudden stop
can cause water hammering and
pressure surges.
1SFC132162F0001
U
rpm
Stop Time
Stop Time
Figure 3: Voltage ramp
1SFC132163F0001
rpm
U
Stop Time
Stop Time
Figure 4: Torque ramp
Parameter
text
Default value Setting range Description
Stop Mode Volt Volt, Torque Type of stop
ramp