Danfoss VACON 3000 Application Manual page 157

VACON® 3000
Application Guide
The Motor Current Limit is not an overcurrent trip limit.
7.8 (ID 108) U/F Ratio
Location in the menu:
• INU application: P3.1.4.1
Use this parameter to set the type of the U/f curve between zero frequency and the field weakening point.
Selec- Selection Description
tion name
num-
ber
0 Linear The voltage of the motor changes linearly as a function of the output frequency. The voltage changes
from the value of P3.1.4.6 (Zero Frequency Voltage) to the value of P3.1.4.3 (Voltage at Field Weakening
Point) at a frequency set in P3.1.4.2 (Field Weakening Point Frequency). Use this default setting if a dif-
ferent setting is not necessary.
1 Squared The voltage of the motor changes from the value of P3.1.4.6 (Zero Frequency Voltage) to the value of
P3.1.4.2 (Field Weakening Point Frequency) at a squared curve. The motor operates undermagnetized
below the field weakening point and produces less torque. You can use the squared U/f ratio in applica-
tions where the torque demand is in relation to the square of the speed, for example in centrifugal fans
and pumps.
2 Program- It is possible to program the U/f curve with 3 different points: the zero frequency voltage (P1), the mid-
mable point voltage/ frequency (P2), and the field weakening point (P3). You can use the programmable U/f
curve at low frequencies if it is necessary to have more torque. You can find the optimal settings auto-
matically with an identification run (P3.1.2.8.1).
U[V]
Un
ID603
A
Illustration 11: Linear and squared change of the motor voltage
Danfoss A/S © 2021.09
N O T I C E
C D
B
E
ID602
AB319735759636en-000101 / DPD01822 | 157
Parameter descriptions
f[Hz]