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Parameter description
1: quadratic
(from voltage P8.7 at 0Hz, to voltage P8.3 at P8.2 frequency)
The voltage of the motor changes from zero point voltage P8.7 following a squared curve form
from zero to the field weakening point P8.3. The motor runs under-magnetized below the field
weakening point and produces less torque. Squared U/f ratio can be used in applications where
torque demand is proportional to the square of the speed, e.g. in centrifugal fans and pumps.
2: programmable
The U/f curve can be programmed with three different points: Zero frequency voltage (P1),
Midpoint voltage/frequency (P2) and Field weakening point (P3).
Programmable U/f curve can be used if more torque is needed at low frequencies. The optimal
settings can automatically be achieved with Motor identification run.
Note: motor identification automatically sets this parameter to 2.
U[V]
Default: Nominal
voltage of the motor
Linear
P1
P8.5
U/
F CURVE MID POINT FREQUENCY
Enabled if P8.4= 2.
Note: motor identification automatically sets this parameter.
P8.6
U/
F CURVE MID POINT VOLTAGE
Enabled if P8.4= 2.
Note: motor identification automatically sets this parameter.
Service support: find your nearest Vacon service center at www.vacon.com
P2
Figure 15. Programmable curve.
P3
Field
weakening
point
Default:
Nominal frequency
of the motor
f[Hz]
vacon • 58
3
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