WEG CFW300 V1.3X, Programming Manual

Page: 68 / 157

V/f Scalar Control
9-6 | CFW300
9
Voltage
applied on
the motor
Output
active
current
Frequency reference
P139
I x R
P136
I x R
automatic
P137
P007
Figure 9.6: Block diagram of the automatic torque boost
P138 - Slip Compensation
Adjustable
Range:
-10.0 to 10.0 % Factory
Setting:
0.0 %
Properties: V/f
Description:
Parameter P138 is used in the motor slip compensation function, when set for positive values. In this case, it
compensates the speed drop due to the application of load on the shaft and, consequently, the slip. Thus, it
increments the output frequency (Δf) considering the increase of the motor active current, as shown in
Figure
9.7 on page 9-6 . In Figure 9.1 on page 9-2 this compensation is represented in the variable
f
Slip
.
The setting in P138 allows regulating with good accuracy the slip compensation by moving the operation
point on the V/f curve, as shown in
Figure 9.7 on page 9-6 . Once P138 is set, the inverter is able to keep the
frequency constant even with load variations.
Negative values are used in special applications where you wish to reduce the output frequency considering
the increase of the motor current.
Eg.: load distribution in motors driven in parallel.
P134 P145
P146
P142
P143
P136
Output
frequency(Hz)
Output
voltage (%)
Δf
Figure 9.7: Slip compensation in an operation point of the standar V/f curve