Emerson Digistart IS1x0043B series User Manual page 38

Safety Rating Mechanical
Information Data Installation
7.2.2 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 (Pr
2C) to a level that will start the motor with a light load, and the current limit (Pr 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.
Figure 7-2 Current ramp soft start
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7.2.3 Adaptive control for starting
Adaptive Control is a new intelligent motor control technique. In an adaptive control soft start, the Digistart IS adjusts the current in
order to start the motor within a specified time and using a selected acceleration profile.
Adaptive Control cannot start the motor faster than a direct on-line (DOL) start. If the start ramp time (Pr 2D) is shorter
than the motor's DOL start time, starting current may reach DOL levels.
CAUTION
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 Digistart IS monitors the motor's performance during each start, to improve control for future soft starts.
Adaptive control
To use Adaptive Control to control starting performance:
1. Select Adaptive Control from the Start Mode menu (Pr 2A)
2. Set the desired Start Ramp Time (Pr 2D)
3. Select the desired Adaptive Start Profile (Pr 2E)
4. Set a start Current Limit (Pr 2B) sufficiently high to allow a successful start. The first Adaptive Control start will be a Constant
Current start. This allows the Digistart IS to learn the characteristics of the connected motor. This motor data is used by the
Digistart IS during subsequent Adaptive Control starts.
Figure 7-3 Adaptive control soft start
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Electrical Keypad Quick Start
Installation and Commissioning
Status
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Time
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Operation Programming Diagnostics Application
1: Initial current (Pr 2C)
2: Start ramp time (Pr 2D)
3: Current limit (Pr 2B)
4: Full voltage current
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Adaptive start profile (Pr 2E):
1. Early acceleration
2. Constant acceleration
3. Late acceleration
4. Start ramp time (Pr 2D)
Technical Maintenance Options
Examples Data
Digistart IS User Guide
Issue: 4