Operating Instructions ACU
18.4.2 Current limit value controller
Via a load-dependent speed control, the current limit value controller ensures that the drive system
is not overloaded. This is extended by the intelligent current limits described in the previous chapter.
The current limit value controller reduces the load on the drive, e.g. during acceleration, by stopping
the acceleration ramp. The switch-off of the frequency inverter which happens when the
acceleration ramps have been set at an excessive gradient is prevented in this way.
The current limit value controller is switched on and off via parameter Operation Mode 610.
The current limit value controller functions and the intelligent current
limits have been deactivated.
The current limit value controller is active.
Behavior in motor operation:
If the current set via parameter Current Limit 613 is exceeded, the activated current limit value
controller will reduce the output frequency until the current limit is no longer exceeded. The output
frequency is reduced as a maximum to the frequency set by the parameter Frequency Limit 614. If
the current value drops below the Current Limit 613 the output frequency is increased to the
setpoint again.
Behavior in generator operation:
If the current set via parameter Current Limit 613 is exceeded, the activated current limit value
controller will increase the output frequency until the current limit is no longer exceeded. The output
frequency is increased, as a maximum, to the set Maximum Frequency 419. If the current value
drops below the Current Limit 613, the output frequency is reduced to the required reference value
again.
The control behavior of the current limit controller can be set via the proportional component,
parameter Amplification 611, and the integrating component, parameter Integral Time 612. If an
optimization of the controller parameters is necessary in exceptional cases, a setting should be made
by way of erratic changes of parameter Current Limit 613.
The dynamism of the current limit value controller and the voltage controller is
influenced by the setting of the parameter Dyn. Voltage Pre-Control 605.
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