Lenze · 8400 BaseLine C · Reference manual · DMS 1.6 EN · 01/2014 · TD05 99
5 Motor control (MCTRL)
5.6 Parameterisable additional functions
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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
( 70)
• 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
-------------- -=
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