Mitsubishi Electric FR-A820-00046 Instruction Manual page 867

Parameters
To detect the regenerative status during deceleration faster (Pr. 884)
Since a rapid change in bus voltage cannot be handled by bus voltage level detection during the re-
generation avoidance operation, deceleration is stopped by detecting the change in bus voltage and
if it is equal or lower than Pr. 883 "Regeneration avoidance operation level".
Set the detectable bus voltage change rate as the detection sensitivity in Pr. 884 "Regeneration avoid-
ance at deceleration detection sensitivity". A larger set value increases the detection sensitivity.
NOTE When the setting value is too small (detection sensitivity is not good), detection will not be possi-
ble, and regeneration avoidance will operate even with the bus voltage change caused by a
change in the input power.
Limit regeneration avoidance operation frequency (Pr. 885)
● It is possible to assign a limit to the output frequency corrected (rise) by the regeneration
avoidance operation.
● Limit of the frequency is output frequency (frequency before regeneration avoidance operation)
+ Pr. 885 "Regeneration avoidance compensation frequency limit value" for during acceleration
and constant speed.
During deceleration, when the frequency increases due to the regeneration avoidance operation
and exceeds the limit value, the limit value will be retained until the output frequency is reduced
to be the half the Pr. 885 setting.
● When the frequency that have increased by the regeneration avoidance operation exceeds Pr. 1
"Maximum frequency", it will be limited to the maximum frequency.
● By setting to Pr. 885 = "9999", regeneration avoidance operation frequency limitation is disabled.
● Set using the motor rated slip frequency as a guideline. Raise the setting value if the overvoltage
protection function (E.OV[]) operation at the start of deceleration.
Rated motor slip frequency =
FR-A800
Synchronized speed at the time of base
frequency - rated rotation speed
Synchronized speed at the time of base
Limit level
Output frequency [Hz]
Pr. 885
Pr. 885/2
Time
frequency
Fig. 5-345:
Limit the output frequency
(G) Control parameters
× Rated motor frequency
I001260E
5 - 687