Vacon 20 CP/X, Руководство по применению

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Parameter description vacon • 60
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4
P8.4 U/
F RATIO SELECTION
0: linear
The voltage of the motor changes linearly as a function of output frequency from zero frequen-
cy voltage P8.7 to the field weakening point (FWP) voltage P8.3 at FWP frequency P8.2 This de-
fault setting should be used if there is no special need for another setting.
Figure 11. Linear and quadratic curve of the motor voltage.
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 P8.7 (P1),
Midpoint voltage/frequencyP8.6/P8.5 (P2) and Field weakening point P8.2/P8.3 (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]
f[Hz]
Default: Nominal
voltage of the motor
Linear
Squared
Field
weakening
point
Default:
Nominal frequency
of the motor