64 Program features
Settings and diagnostics
Parameter group 37 User load curve.
Events: A8BE ULC overload warning, A8BF ULC underload warning, 8001 ULC
underload fault, 8002 ULC overload faul
U/f ratio
The U/f function is only available in scalar motor control mode, which uses frequency
control.
The function has two modes: linear and squared.
In linear mode, the ratio of voltage to frequency is constant below the field weakening
point. This is used in constant torque applications where it may be necessary to
produce torque at or near the rated torque of the motor throughout the frequency
range
In squared mode, the ratio of the voltage to frequency increases as the square of the
frequency below the field weakening point. This is typically used in centrifugal pump
or fan applications. For these applications, the torque required follows the square
relationship with frequency. Therefore, if the voltage is varied using the square
relationship, the motor operates at improved efficiency and lower noise levels in
these applications.
The U/f function cannot be used with energy optimization; if parameter 45.11 Energy
optimizer is set to Enable, parameter 97.20 U/F ratio is ignored.
Settings and diagnostics
Parameter 97.20 U/F ratio (page 288).
Events: -
ACS180 FW.book Page 64 Tuesday, March 9, 2021 2:25 PM
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