Constant Current With Current Ramp - Danfoss VLT MCD 600 Operating Manual

Operating Guide | VLT® Soft Starter MCD 600
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1 Initial current (set in parameter 2-3 Initial Current)
3 Full voltage current
Illustration 26: Example of Constant Current

9.8.2 Constant Current with Current Ramp

Current ramp soft starting raises the current from a specified starting level (1) to a maximum limit (3) over an extended period (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 parameter 2-3 Initial Current to
a level that will start the motor with a light load. Then, set parameter 2-4 Current Limit to a level that will start the motor with a
heavy load.
• The load breaks away easily, but starting time has to be extended (for example a centrifugal pump where pipeline pressure has to
build up slowly).
• The electricity supply is limited (for example a generator set), and a slower application of load allows greater time for the supply to
respond.
58 | Danfoss A/S © 2018.10
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Rotor speed (% full speed)
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2 Current limit (set in parameter 2-4 Current Limit)
Operation
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