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4.20.3 Regeneration avoidance function (Pr. 665, Pr. 882, Pr. 883, Pr. 885, Pr. 886)
(1) What is regeneration avoidance function? (Pr. 882, Pr. 883)
When the regeneration load is large, 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 regeneration status.
The regeneration avoidance function is always on when "1" is set in Pr. 882, and activated only during a constant speed
when "2" is set in Pr. 882.
This function detects a regeneration status and increases the frequency to avoid the regenerative status.
Possible to avoid regeneration by automatically increasing the frequency to 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
200V 
class
400
VDC
300 to 800V
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 
× 
".
400V 
class
780
VDC
885
Regeneration 
avoidance 
compensation 
frequency limit value
6Hz
0 to 10Hz
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%
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%
The above parameters can be set when Pr. 160 Extended function display selection = "0". (Refer to page 162)
2
Bus voltage 
(VDC)
Regeneration avoidance operation example 
for acceleration
Pr. 883
Output  
frequency 
(Hz)
During regeneration  
avoidance function operation
Time
Time
Bus voltage 
(VDC)
Regeneration avoidance operation example 
for constant speed
Pr. 883
Output  
frequency 
(Hz)
During regeneration avoidance 
function operation
Time
Time
Bus voltage
(VDC)
Regeneration avoidance 
operation example for deceleration
Pr. 883
Output
frequency
(Hz)
Time
Time
During regeneration 
avoidance function operation