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Manual torque boost
In manual torque boost mode, the inverter maintains the output at a constant level
regardless of the load. When you use this mode, select the appropriate V/f pattern
(variable torque or constant torque characteristics) with Load Selection (F37). To
keep the motor starting torque, manually select optimal inverter output voltage for
the motor and load by setting an optimal torque boost rate to F09 in accordance with
the motor and its load.
Setting an excessive torque boost rate may result in over-excitation and overheat of
the motor during light or no load operation.
Manual torque boost keeps the output voltage constant even if the load varies,
assuring stable motor operation.
Variable torque characteristics (F37 = 0)
Constant torque characteristics (F37 = 1)
• Set an appropriate torque boost rate that will keep the starting torque
of the motor within the voltage level in the low frequency zone. Setting
an excessive torque boost rate may result in over-excitation or over-
heat of the motor during no load operation.
• The F09 data setting is effective when F37 (Load Selection/Auto
Torque Boost/Auto Energy Saving Operation) is set to 0, 1, 3, or 4.
Automatic torque boost
This feature automatically optimizes the output voltage to fit the motor and its load.
Under a light load, it decreases the output voltage to prevent the motor from
over-excitation; under a heavy load, it increases the output voltage to increase
torque.
Since this feature is related to the motor properties, it is necessary to set the rated
voltage at base frequency (F05) and motor parameters (P codes) properly.
For the automatic torque boost feature, which is related to the moto
characteristics, you need to consistently set the voltage at the base
frequency (F05) and motor parameters P02, P03 and P99 appropriately
for the motor rating and characteristics.
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 characteristics before using this feature.)
The inverter enables this feature for constant speed operation only. During accel-
eration and deceleration, the inverter will run with manual or automatic torque boost,
depending on 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.
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