Lenze 8400 motec - Manual (Page 121)

Lenze · 8400 motec · Reference manual · DMS 4.1 EN · 08/2013 · TD05 121
5 Motor control (MCTRL)
5.7 V/f control (VFCplus + encoder)
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Controller limitation
Max. intervention of the controller is limited by the controller limitation (
C00971/1 ).
• The controller can be limited depending on the application.
• We recommend to limit the max. intervention to twice the rated slip of the motor.
• The rated slip is calculated as follows:
[5-4] Calculation of the rated slip
Slip limitation
In addition to limiting the slip regulator, the field frequency to be injected can also be limited by
another limiting element, the slip limitation ( C00971/2 ).
• If the slip is e.g. limited to twice the rated slip of the motor, a stalling of the motor during very
dynamic processes can be avoided.
• Motor stalling is caused by:
• a high overcurrent at very steep speed ramps
• very fast speed changes due to load, e.g. abrupt stopping of the drive due to an encounter
with a stop or a load that is not moving.
f
Slip
Rated
Hz [ ] f
Rated
Hz [ ]
n
Motor
Rated
rpm [ ]
60
------------------------------------------ p
Number of pole pairs
⋅
 
 
– =

Note!
A setting of C00971/1 = 0 Hz deactivates the slip regulator. In this case, the structure of
the V/f control corresponds to the structure of a V/f characteristic control without
feedback.