Mitsubishi Electric FR-D720S SC EC, Instruction Manual

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Special operation Parameter
6 - 268
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 always on when "1" is set in Pr. 882 and activated only
during a constant speed when "2" is set in Pr. 882.
I001257E
Fig. 6-137: 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 220 V, the bus voltage is about 311 V DC and when the input volt-
age 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 over voltage stall (oL) stops the output frequency during deceleration, the regenera-
tion avoidance function is always on and increases the frequency according to the regenera-
tion amount.
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
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]