ASTAT XL User Manual
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7.5.2
Current Ramp
Current ramp soft starting raises the current from a specified starting level (1) to a maximum limit (3),
over an extended period of time (2).
Current ramp starting can be useful for applications where:
•
the load can vary between starts (for example a conveyor which may start loaded or unloaded).
Set the initial current (parameter 2C
)
to a level that will start the motor with a light load, and the
current limit (parameter 2B)
to a level that will start the motor with a heavy load.
•
the load breaks away easily, but starting time needs to be extended (for example a centrifugal
pump where pipeline pressure needs to build up slowly).
•
the electricity supply is limited (for example a generator set), and a slower application of load will
allow greater time for the supply to respond.
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1: Initial current (parameter 2C)
2: Start ramp time (parameter 2D)
3: Current limit (parameter 2B)
4: Full voltage current
Time
7.5.3
Adaptive Control for Starting
In an adaptive control soft start, the ASTAT XL adjusts the current in order to start the motor within a
specified time and using a selected acceleration profile.
CAUTION
Adaptive Control cannot start the motor faster than a direct on-line (DOL) start. If the start ramp
time (parameter 2D) is shorter than the motor's DOL start time, starting current may reach DOL
levels.
Every application has a particular starting profile, based on characteristics of the load and the motor.
Adaptive Control offers three different starting profiles, to suit the requirements of different
applications. Selecting a profile that matches the inherent profile of the application can help smooth
out acceleration across the full start time. Selecting a dramatically different Adaptive Control profile
can somewhat neutralise the inherent profile.
The ASTAT XL monitors the motor's performance during each start, to improve control for future soft
starts.
7.5.3.1
Adaptive Control
To use Adaptive Control to control starting performance:
1.
Select Adaptive Control from the Start Mode menu (parameter 2A)
2.
Set the desired Start Ramp Time (parameter 2D
)
3.
Select the desired Adaptive Start Profile (parameter 2J)
4.
Set a start Current Limit (parameter 2B) sufficiently high to allow a successful start. The first
Adaptive Control start will be a Constant Current start. This allows the ASTAT XL to learn the
characteristics of the connected motor. This motor data is used by the ASTAT XL during
subsequent Adaptive Control starts.
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Adaptive start profile (parameter 2J):
1. Early acceleration
2. Constant acceleration
3. Late acceleration
4. Start ramp time (parameter 2D)
Time
