Regeneration Avoidance Function (Pr. 665, Pr. 882 To Pr. 886) - Mitsubishi Electric FR-A720-0.4K Instruction Manual

4.25.7 Regeneration avoidance function (Pr. 665, Pr. 882 to Pr. 886)

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
Name
Number
Regeneration
882 avoidance operation
selection
Regeneration
883 avoidance operation
level
Regeneration
avoidance at
884
deceleration
detection sensitivity
Regeneration
avoidance
885
compensation
frequency limit value
Regeneration
886 avoidance voltage
gain
Regeneration
665 avoidance frequency
gain
(1) What is regeneration avoidance function? (Pr. 882, Pr. 883)
⋅ When the regenerative status is serious, the DC bus voltage rises and an overvoltage alarm (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.
Regeneration avoidance operation
example for acceleration
Pr.883
During regeneration
avoidance function operation
⋅ Setting Pr. 882 to "1, 2" validates the regeneration avoidance function.
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
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.
⋅ While overvoltage stall (
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.
Initial Setting
Value Range
0
1
0
2
380VDC/
300 to 800V
760VDC *
0
0
1 to 5
0 to 10Hz
6Hz
9999
100% 0 to 200%
100% 0 to 200%
Regeneration avoidance operation
example for constant speed
Pr.883
Time
During regeneration
avoidance function operation
Time
times greater than the input voltage.
2
) is activated only during deceleration and stops the decrease in output frequency, the regeneration
Special operation and frequency control
Description
Regeneration avoidance function invalid
Regeneration avoidance function is always valid
Regeneration avoidance function is valid only during a constant
speed operation
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 ×
.
2
* The initial value differs according to the voltage level. (200V / 400V)
Regeneration avoidance by bus voltage change ratio is invalid
Set sensitivity to detect the bus voltage change ratio
Setting 1
Detection sensitivity low
Set the limit value of frequency which rises at activation of
regeneration avoidance function.
Frequency limit invalid
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 the load inertia of the motor is large, decrease the Pr. 886
setting. When vibration is not suppressed by decreasing the Pr.
886 setting, set a smaller value in Pr. 665.
Regeneration avoidance operation
example for deceleration
Pr.883
Time
During regeneration
avoidance function operation
Time
5
high
Time
Time
363
Pr.881
page 110
Pr.888
page 371
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