Mitsubishi Electric FR-A700 EC, Instruction Manual

Page: 704 / 826

Special operation Parameter
6 - 524
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
첸
) 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.
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.
I001257E
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
√
2 times greater than the input voltage
(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.
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.
Bus
v
o
ltag
e
[V D
C
]
Output
frequency [Hz]
Regeneration avoidance operation
example for acceleration Regeneration avoidance operation
example for constant speed Regeneration avoidance operation
example for deceleration
Pr. 883
Pr. 883
Pr. 883
During regeneration avoidance
function operation
During regeneration avoidance
function operation
Time
Time
Time
Bus
v
o
ltag
e
[V D
C
]
Output
frequency [Hz]
Bus
v
o
ltag
e
[V D
C
]
Output
frequency [Hz]
During regeneration avoidance
function operation