Mitsubishi Electric FR-A700 Instruction Manual page 704

Special operation
What is regeneration avoidance function? (Pr. 882, Pr. 883)
When the regeneration status is serious, the DC bus voltage rises and an over voltage 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 regeneration status.
The regeneration avoidance function is performed during any of acceleration, constant speed
and deceleration.
Regeneration avoidance operation
example for acceleration
Fig. 6-262: Regeneration avoidance function
NOTES
The inclination of the frequency increased or decreased by the regeneration avoidance func-
tion changes depending on the regeneration status.
The DC bus voltage of the inverter is normally about
(when the input voltage is 440V AC, the bus voltage is about 622V DC). 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 (oL) 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.
To detect the regeneration status during deceleration faster (Pr. 884)
As the regeneration avoidance function cannot respond to an abrupt voltage change by detec-
tion of the bus voltage level, the ratio of bus voltage change is detected to stop deceleration if
the bus voltage is less than Pr. 883 "Regeneration avoidance operation level". Set that detect-
able bus voltage change ratio to Pr. 884 as detection sensitivity. Increasing the setting raises the
detection sensitivity.
NOTE Too small setting (low detection sensitivity) will disable detection, and too large setting will
turn on the regeneration avoidance function if the bus voltage is varied by an input power
change, etc.
6 - 524
Pr. 883
Time
During regeneration avoidance
function operation
Regeneration avoidance operation
example for constant speed
Pr. 883
Time
During regeneration avoidance
function operation
√
2 times greater than the input voltage
Parameter
Regeneration avoidance operation
example for deceleration
Pr. 883
During regeneration avoidance
function operation
I001257E
Time