ABB PST72 Installation And Commissioning Manual

Functions
Chapter 10
132
1SFC132003M0201
10:2 Start mode
Path in menu:
Menu/SETTINGS/Functional Settings/
Torque control/ Start Mode
Using the PST softstarter it is possible to choose between
two different types of start ramps. These are voltage ramp
and torque ramp.
Voltage ramp When using the voltage ramp, the voltage
is increased linearly from the start level to
full voltage during start. 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 the start level to full voltage
during start. This has the benefit that the
mechanical starting behavior of the
equipment driven by the motor will be
much softer than when using voltage
ramp.
1SFC132160F0001
U
rpm
TimeStart
TimeStart
Figure 1: Voltage ramp
U
rpm
1SFC132161F0001
TimeStart
TimeStart
Figure 2: Torque ramp
Parameter
text
Default value Setting range Description
Start Mode Volt Volt, Torque Type of start
ramp

ABB PST72 Specifications

General

Brand	ABB
Model	PST72
Category	Controller
Language	English