Operating Instructions ACTIVE 06/07178
178 Operating Instructions ACTIVE 06/07
16.5.3.2 Limit Value Sources
As an alternative to limiting the output values by a fixed value, linking to an analog
input value is also possible. The analog value is limited via parameters
Minimum Ref-
erence Percentage
518 and Maximum Reference Percentage 519, but does not con-
sider the
Gradient Percentage Ramp 477 of the reference percentage value channel.
The assignment is done with the help of the parameters
Isq Limit Source Motor Op-
eration
734 and Isq Limit Source Generator Op. 735 for the torque-forming current
component Isq.
The sources for torque limits are selectable via parameters
Torque Limit Source Mo-
tor Op
736 and Torque Limit Source Gen. Op.737
Operation mode 736, 737 Function
101 - Analog Input MFI1A
The source is the multifunctional input 1 in an
analog
Operation Mode 452.
105 - Rep. Frequency Input (F3)
The frequency signal on the repetition frequency
input corresponding to
Operation Mode 496.
110 - Fixed Limit
The selected parameter values for limiting the
speed controller are taken into account.
Note: The limit values and assignment to different limit value sources are data
set related in the configurations. The use of the data set change-over
demands an examination of the parameters in question.
16.5.4 Acceleration Pre-Control
The acceleration pre-control is active in the speed-controlled configurations and can
be activated via parameter
Operation Mode 725 for acceleration pre-control.
Operation Mode 725 Function
0 - Off The control system is not influenced.
1 - Switched on
The acceleration pre-control is active according to
the limit values.
The acceleration pre-control controlled parallel to the speed controller reduces the
reaction time of the drive system to a change of reference values. The minimum ac-
celeration time defines the modification speed of the reference speed value as from
which a torque necessary for acceleration of the drive is pre-controlled. The accelera-
tion of the mass is a function of the
Mech. Time Constant 727 of the system. The
value calculated from the increase of the reference value and the multiplication factor
of the torque required is added to the output signal of the speed controller.
Parameter Settings
No. Description Min. Max. Fact. sett.
726 Minimum Acceleration 0.1 Hz/s 6500.0 Hz/s 1.0 Hz/s
727 Mech. Time Constant 1 ms 60000 ms 10 ms
For optimal setting, the acceleration pre-control is switched on and the mechanical
time constant is set to the minimum value. The output value of the speed controller is
compared to the minimum acceleration time during the acceleration processes. The
frequency ramp is to be set to the highest value occurring in operation at which the
output value of the speed controller is not yet limited. Now, the value of the
Minimum
Acceleration
726 is set to half the set acceleration ramp so that it is ensured that the
acceleration pre-control is active. The acceleration pre-control is not raised by increas-
ing the
Mech. Time Constant 727 until the output values corresponds to the time
modification of the drive during the acceleration processes.
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