9.2 Details of Function Codes
9-27
Chap. 9 FUNCTION CODES
F37 Load Selection/Auto Torque Boost/Auto Energy Saving Operation
Allows you to select the load type and enable/disable auto torque boost and auto energy saving
operation. The load selection enables an optimal V/f pattern to be selected.
Load selection
There are two different properties of loads--the torque load which is in proportion to the square
of speed and the constant torque load. You can select a V/f pattern optimized to the load
property. Refer to the figure in the descriptions for function code F09 for details.
Auto torque boost
This feature optimizes the output voltage automatically to the motor and its load. Even if the
load varies, the inverter can maintain the exciting current fed to the motor so as not to
over-excite the motor. The maximum output torque of the motor will be increased.
• If the automatic torque boost is enabled (F37 = 2 or 5), function code F09 will be
ignored.
• If either the torque in proportion to the square of the speed or the constant torque
is selected (F37 = 0, 1, 3, or 4), it is necessary to modify the F09 data (Torque
boost: 0.0 to 20.0%).
• If a motor parameter is a special one or the rigidity of the load is not sufficient,
lowering the maximum output torque or unstable operation may sometimes
result. To avoid this happening, disable the automatic torque boost (F37 = 0 or 1)
and set the torque boost with F09 manually.
Auto energy saving operation
This feature controls the terminal voltage of the motor automatically to minimize the motor
power loss. (Note that this feature may not be effective depending upon the motor
characteristics. Check the properties before using this feature.)
The inverter enables this feature for constant speed operation only. During acceleration and
deceleration, the inverter will run with manual or automatic torque boost, depending on the data
setting of function code F37. If auto energy-saving operation is enabled, the response to a
change in motor speed may be slow. Do not use this feature for a system that requires quick
acceleration and deceleration.
Data for F37 Load selection
Auto torque
boost
Auto energy
saving
F09 Remarks
0
Variable torque
Disabled Disabled Enabled
1
Constant torque
Disabled Disabled Enabled
2
Not available
Enabled Disabled Disabled
3
Variable torque
Disabled Enabled Enabled
4
Constant torque
Disabled Enabled Enabled
5
Not available
Enabled Enabled Disabled
The auto energy-saving
feature is enabled only for
constant speed operation.
During acceleration/
deceleration, the inverter
runs with manual or
automatic torque boost.
When using the auto torque boost or energy-saving feature, you need to set the rated
voltage of the motor to F05 (Voltage at the base frequency) and the moto
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