Lenze 8400 BaseLine D - Manual (Page 100)

5 Motor control (MCTRL)
5.6 Parameterisable additional functions
100
Lenze · 8400 BaseLine D · Reference manual · DMS 5.5 EN · 01/2014 · TD05
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5.6.4 Slip compensation
Under load, the speed of an asynchronous machine decreases. This load-dependent speed drop is
called slip. The slip can partly be compensated for by the setting in C021 .
• The setting of C021 can be done automatically in the course of motor parameter identification.
 Automatic motor data identification ( 71)
• The setting must be made manually if the motor parameter identification cannot be called up.

How to set the slip compensation manually:
1. Calculate the slip compensation according to motor nameplate data:
2. Transfer the calculated slip constant s in C021 .
3. Correct the setting in C021 while the drive is running until the load-dependent speed drop
does not occur anymore between idling and maximum load of the motor in the desired
speed range.

Tip!
The following guide value applies to a correctly set slip compensation:
• Deviation from the rated motor speed ≤ 1% for the speed range of 10 % ... 100 % of the
rated motor speed and loads ≤ rated motor torque.
• Greater deviations are possible in the field weakening range.
•
C021 is set too high, the drive may get unstable.
.
• Negative slip ( C021 < 0) with V/f characteristic control results in "smoother" drive beha-
viour at heavy load impulses or applications requiring a significant speed drop under
load.
Parameter Info Lenze setting
Value Unit
C021 Slip compensation 0.00 %
s Slip constant ( C021 ) [%]
n
rsyn
Synchronous motor speed [rpm]
n
r
Rated motor speed according to the motor
nameplate [rpm]
f
r
Rated motor frequency according to the mo-
tor nameplate [Hz]
p Number of motor pole pairs (1, 2, 3 ...)
s
n
rsyn
n
r
–
n
rsyn
----------------------- 100% ⋅ =
n
rsyn
f
r
60 ⋅
p
--------------- =