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CHAPTER 6 - DETAILED PARAMETER DESCRIPTION
Range
[Factory Setting]
Parameter
P138
Slip
Compensation
0.0 to 10.0
[ 0.0 ]
0.1 %
Description / Notes
The parameter P138 is used in the motor slip compensation function.
This function compensates the drop of the motor speed
due to load, which is a inherent characteristic relating
to the operation principle of the induction motor.
This speed drop is compensated by increasing the
output frequency (applied to the motor) as a function
of the increase of the active motor current, as shown
in the block diagram and in the V/F curve below.
Frequency
Reference (F*)
Ramp Input
Frequency (Fe)
Slip
Compensation
Active Output
Current (Ia)
Filter
F
P138
Figure 6.9 - Block diagram of the slip compensation function
Output Voltage
(function of
the motor
load)
Output
Frequency
Figure 6.10 - V/F curve with slip compensation
To set the parameter P138 adopt the following
procedure:
- run the motor without load up to approximately
half of the application top speed;
- measure the actual motor or equipment speed;
- apply rated load to equipment;
- increase parameter P138 until the speed reaches
its no-load speed.
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