Danfoss VACON 3000 Application Manual page 202

VACON® 3000
Application Guide
You can adjust the motor underload protection with parameters P3.9.4.2 (Underload Protection: Field Weakening Area Load) and
P3.9.4.3 (Underload Protection: Zero Frequency Load). The underload curve is a squared curve between the zero frequency and the
field weakening point. The protection is not active below 5 Hz. The underload time counter does not operate below 5 Hz.
The values of the underload protection parameters are set in percentage of the nominal torque of the motor. To find the scaling
ratio for the internal torque value, use the data in the name plate data of the motor, the motor nominal current and the nominal
current of the drive IH. If you use another current than the nominal motor current, the precision of the calculation decreases.
If you use long motor cables (max. 100 m) with small drives (≤1.5 kW), the motor current that the drive measures can be much
higher than the actual motor current. It is because there are capacitive currents in the motor cable.
7.163 (ID 714) Underload Protection: Field Weakening Area Load
Location in the menu:
• INU application: P3.9.4.2
Use this parameter to set the minimum torque that the motor needs when the output frequency of the drive is higher than the
frequency of the weakening point. You can set the value of this parameter between 10.0% and 150.0% x T
limit for the minimum torque when the output frequency is above the field weakening point.
Changing parameter ID 113 Motor Nominal Current restores this parameter automatically to its default value. See
derload Fault.
A
ID714
B
ID715
5 Hz
Illustration 41: Setting of the minimum load
A Torque
B Underload area
7.164 (ID 715) Underload Protection: Zero Frequency Load
Location in the menu:
• INU application: P3.9.4.3
Use this parameter to set the minimum torque that the motor needs when the output frequency of the drive is 0.
Changing the value of parameter P3.1.1.4 Motor nominal current restores this parameter automatically to the default value.
7.165 (ID 716) Underload Protection: Time Limit
Location in the menu:
•
INU application: P3.9.4.4
Use this parameter to set the maximum time for an underload state. It is the maximum time for the underload state to be active
before an underload fault occurs.
202 | Danfoss A/S © 2021.09
N O T I C E
f
C
C Field weakening point
AB319735759636en-000101 / DPD01822
Parameter descriptions
. This value is the
nMotor
7.162 (ID 713) Un-