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Special operation and frequency control
4
PARAMETERS
4.25.7 Regeneration avoidance function (Pr. 665, Pr. 882 to Pr. 886)
(1) What is regeneration avoidance function? (Pr. 882, Pr. 883)
⋅ When the regenerative status is serious, the DC bus voltage rises and an overvoltage fault (E. OV) may occur.
When this bus voltage rise is detected and the bus voltage level reaches or exceeds Pr. 883, increasing the
frequency avoids the regenerative status.
⋅ For regeneration avoidance operation, you can select whether it is always activated or activated only at a constant
speed.
⋅ Setting Pr. 882 to "1, 2" validates the regeneration avoidance function.
This function detects a regenerative status and increases the frequency to avoid the regenerative status.
Possible to avoid regeneration by automatically increasing the frequency and continue operation if the fan
happens to rotate faster than the set speed due to the effect of another fan in the same duct.
Parameter
Number
Name
Initial
Value
Setting
Range
Description
882
Regeneration
avoidance operation
selection
0
0 Regeneration avoidance function invalid
1 Regeneration avoidance function is always valid
2
Regeneration avoidance function is valid only during a constant
speed operation
883
Regeneration
avoidance operation
level
380VDC/
760VDC *
300 to 800V
Set the bus voltage level at which regeneration avoidance operates.
When the bus voltage level is set to low, overvoltage error will be
less apt to occur. However, the actual deceleration time increases.
The set value must be higher than the power supply voltage × .
* The initial value differs according to the voltage level. (200V / 400V)
884
Regeneration
avoidance at
deceleration
detection sensitivity
0
0 Regeneration avoidance by bus voltage change ratio is invalid
1 to 5
Set sensitivity to detect the bus voltage change ratio
Setting 1 5
Detection sensitivity low high
885
Regeneration
avoidance
compensation
frequency limit value
6Hz
0 to 10Hz
Set the limit value of frequency which rises at activation of
regeneration avoidance function.
9999 Frequency limit invalid
886
Regeneration
avoidance voltage
gain
100% 0 to 200%
Adjust responsiveness at activation of regeneration avoidance. A
larger setting will improve responsiveness to the bus voltage
change. However, the output frequency could become unstable.
When vibration is not suppressed by decreasing the Pr. 886
setting, set a smaller value in Pr. 665.
665
Regeneration
avoidance frequency
gain
100% 0 to 200%
REMARKS
⋅ The inclination of the frequency increased or decreased by the regeneration avoidance function changes depending on the
regenerative status.
⋅ The DC bus voltage of the inverter is normally about times greater than the input voltage.
When the input voltage is 220VAC (440VAC), the bus voltage is about 311VDC (622VDC).
However, it varies with the input power supply waveform.
⋅ The Pr. 883 setting should be kept higher than the DC bus voltage level. Otherwise, the regeneration avoidance function is
always ON even in the non-regeneration status and the frequency increases.
⋅ While overvoltage stall ( ) is activated only during deceleration and stops the decrease in output frequency, the regeneration
avoidance function is always ON (Pr. 882 = 1) or activated only during a constant speed (Pr. 882 = 2) and increases the
frequency according to the regeneration amount.
2
Pr. 883
Time
Time
Regeneration avoidance operation
example for acceleration
Bus voltage
(VDC)
Output
frequency(Hz)
During regeneration
avoidance function operation
Pr. 883
Time
Time
Regeneration avoidance operation
example for constant speed
Bus voltage
(VDC)
Output
frequency(Hz)
During regeneration
avoidance function operation
Pr. 883
Time
Time
Bus voltage
(VDC)
Output
frequency(Hz)
During regeneration
avoidance function operation
Regeneration avoidance operation
example for deceleration
2