17.5.3.1 Torque Reference
The reference torque can be specified as follows:
− Set parameter n-/T-Control Change-Over 164 to "6 - On" or link it to a digital
signal and switch this on.
− Via parameter
Reference Percentage Source 1 476 or Reference Percentage
Source 2
494, select a source for the reference torque.
For example:
− The reference torque can be set via the arrow keys of the operator panel if the
following setting is selected:
Reference Percentage Source 2 494 = "5 - keypad
motorpoti (factory setting)".
− The reference torque can be set via multifunction input 1 (MFI1A) if the following
setting is selected:
Reference Percentage Source 1 476 = "1 - analog value
MFI1A (factory setting)".
− 100 % Torque refer to the calculated Torque from
Rated Mech. Power 376 (Mo-
tor power) and
Rated Speed 372 (Motor nominal speed).
Parameter
Torque 224 shows the actual torque.
Select an applicable operation mode for parameter
Start 645. Refer to chapter 12.5 “Search Run”.
17.5.3.2 Upper and lower limit of the frequency in Torque Control
In many cases limitation of the speed is required in the operating points with reduced
or without load torque, because the speed regulates itself to the torque reference
and the load behavior.
To avoid an unintentional speed (mostly too high speeds, in
some cases also too small speeds and avoidance of current impression), the frequen-
cy is limited by
Frequency upper limit 767 and Frequency lower limit 768
speed controller.
As from the limit value the drive is controlled to maximum speed (Frequency Upper
Limit
767 and Frequency Lower Limit 768), which corresponds to the behavior of
the speed controller. Additionally, the controller limits the speed to
Maximum Fre-
quency
419. This limitation is set by the speed controller – changes in the speed
controller affect the speed behavior in the limit area of the 3 mentioned parameters.
In the current impression, the speed is limited additional to Minimum Frequency 418
– in Direct Torque Control this limit is not active.
Positive values limit the speed in clockwise direction; negative values limit the speed
in anticlockwise direction. In example, if both values are positive (> 0 Hz),
anticloc
k-
wise movement is inhibited.
WARNING
If the torque control is activated while the actual frequency lies outside the defined
range of Frequency Upper Limit 767 and Frequency Lower Limit 768
when
switching on a stopped machine or when the Flying start synchronizes), the
allowed frequency is driven to without ramps. The torque is only limited by the limita-
tions of the speed controller (current and torque). Therefore an unexpected dynamic
behavior can occur.
230 Operating Instructions ACU 06/13
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