Fuji Electric FRENIC-HVAC User Manual page 387

• Auto torque boost
This function automatically optimizes the output voltage to fit the motor with its load. Under
light load, auto torque boost decreases the output voltage to prevent the motor from
over-excitation. Under heavy load, it increases the output voltage to increase the output
torque of the motor.
• Since this function relies also on the characteristics of the motor, set the base
frequency 1 (F04), the rated voltage at base frequency 1 (F05), and other
pertinent motor parameters (P01 through P03 and P06 through P99) in line with
the motor capacity and characteristics, or else perform auto-tuning (P04).
• When a special motor is driven or the load does not have sufficient rigidity, the
maximum torque might decrease or the motor operation might become unstable.
In such cases, do not use auto torque boost but choose manual torque boost using
F09 (F37 = 0 or 1).
Auto energy saving operation

This feature automatically controls the supply voltage to the motor to minimize the total
power loss of motor and inverter. (Note that this feature may not be effective depending upon
the motor or load characteristics. Check the advantage of energy saving before you actually
apply this feature to your machinery.)
Auto energy saving operation applies only to constant speed operation. During
acceleration/deceleration, torque boost specified by F09 or auto torque boost applies
depending upon the setting of F37.
If auto energy saving operation is enabled, the response to a motor speed change from
constant speed operation may be slow. Do not use this feature for such machinery that
requires quick acceleration/deceleration.
• Use auto energy saving only where the base frequency is 60 Hz or lower. If the
base frequency is set at 60 Hz or higher, you may get a little or no energy saving
advantage. The auto energy saving operation is designed for use with the
frequency lower than the base frequency. If the frequency becomes higher than
the base frequency, the auto energy saving operation will be invalid.
• Since this function relies also on the characteristics of the motor, set the base
frequency 1 (F04), the rated voltage at base frequency 1 (F05), and other
pertinent motor parameters (P01 through P03 and P06 through P99) in line with
the motor capacity and characteristics, or else perform auto-tuning (P04).
6.3 Details of Function Codes
6-77