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Digistart IS User Guide
39
Issue: 4
www.controltechniques.com
NOTE
Adaptive Control will control the load according to the programmed profile. Start current will vary according to the
selected acceleration profile and the programmed start time.
If replacing a motor connected to a Digistart IS programmed for Adaptive Control starting or stopping, or if the starter
has been tested on a different motor prior to actual installation, the starter will need to learn the characteristics of the
new motor. The Digistart IS will automatically re-learn the motor's characteristics if Pr
1A
Motor Full Load Current
or Pr
2L
Adaptive Control Gain
is changed.
How to select the adaptive control start profile
The best profile will depend on the exact details of each application.
Some loads, such as submersible pumps, should not be run at slow speeds. An early acceleration profile will raise the speed
quickly, then control acceleration through the rest of the start.
CAUTION
Adaptive Control controls the motor's speed profile, within the programmed time limit. This may result in a higher level
of current than traditional control methods.
Fine-tuning adaptive control
If the motor does not start or stop smoothly, adjust the adaptive control gain (Pr
2L
). The gain setting determines how much the
Digistart IS will adjust future adaptive control starts and stops, based on information from the previous start. The gain setting affects
both starting and stopping performance.
If the motor accelerates or decelerates too quickly at the end of a start or stop, increase the gain setting by 5% to 10%.
If the motor speed fluctuates during starting or stopping, decrease the gain setting slightly.
NOTE
Changing the gain setting resets the starter's adaptive control learning. The first start after changing the gain will use
constant current.
7.2.4
Kickstart
Kickstart provides a short boost of extra torque at the beginning of a start, and can be used in conjunction with current ramp or
constant current starting.
Kickstart can be useful to help start loads that require high breakaway torque but then accelerate easily (for example flywheel loads
such as presses).
Figure 7-4 Current ramp soft start with kickstart
C
ur
re
nt
(%
mot
or
fu
ll
loa
d
cu
rre
nt
)
1
2
6
4
5
3
1: Kickstart level (Pr
2F
)
2: Kickstart time (Pr
2G
)
3: Initial current (Pr
2C
)
4: Start ramp time (Pr
2D
)
5: Current limit (Pr
2B
)
6: Full voltage current
Rotor speed (% full speed)
CAUTION
Kickstart subjects the mechanical equipment to increased torque levels. Ensure the motor, load and couplings can
handle the additional torque before using this feature.
7.3
Stop methods
Soft starters offer a variety of methods for the control of motor stopping.
Table 7-3 Soft stop methods
Stop Method
Performance Result
Coast To Stop
Natural load run down
TVR Soft Stop
Extended run down time
Adaptive Control
Extended run down time according to selected deceleration profile
Brake
Reduced run down time
Soft starters are often used in pumping applications to eliminate the damaging effects of fluid hammer. Adaptive Control should be
the preferred stop method for these applications.
To stop the motor, press the
STOP
button on the keypad or activate the Stop remote input. The motor will stop using the stop
mode selected in Pr
2H
.
