Mitsubishi Electric FR-A700 Instruction Manual page 705

Parameter
Limit regeneration avoidance operation frequency (Pr. 885)
You can limit the output frequency compensated for (increased) by the regeneration avoidance
function.
The frequency is limited to the output frequency (frequency prior to regeneration avoidance
operation) + Pr. 885 "Regeneration avoidance compensation frequency limit value" during
acceleration or constant speed. If the regeneration avoidance frequency exceeds the limit value
during deceleration, the limit value is held until the output frequency falls to 1/2 of Pr. 885.
When the regeneration avoidance frequency has reached Pr. 1 "Maximum frequency", it is lim-
ited to the maximum frequency.
Pr. 885 is set to "9999", the frequency setting is invalid.
Regeneration avoidance function adjustment (Pr. 665, Pr. 886)
If the frequency becomes unstable during regeneration avoidance operation, decrease the set-
ting of Pr. 886 "Regeneration avoidance voltage gain". Reversely, if sudden regeneration
causes an overvoltage alarm, increase the setting.
When the load inertia of the motor is large, decrease the Pr. 886 setting. When vibration is not
suppressed by decreasing the Pr. 886 "Regeneration avoidance voltage gain" setting, set a
smaller value in Pr. 665 "Regeneration avoidance frequency gain". When the load inertia of the
motor is large, decrease the Pr. 886 setting.
NOTES
When regeneration avoidance operation is performed, "oL" (over voltage stall) is displayed
and the OL signal is output.
When regeneration avoidance operation is performed, stall prevention is also activated at
the same time.
The regeneration avoidance function cannot shorten the actual deceleration time taken to
stop the motor. The actual deceleration time depends on the regeneration capability. When
shortening the deceleration time, consider using the regeneration unit (FR-BU, MT-BU5,
FR-CV, FR-HC, MT-HC).
When using the regeneration unit (FR-BU, MT-BU5, FR-CV, FR-HC, MT-HC), set Pr. 882 to
"0" (initial value) (regeneration avoidance function invalid).
When regeneration avoidance operation is performed, the OL signal output item of Pr. 156
also becomes the target of oL (over voltage stall). Pr. 157 "OL signal output timer" also
becomes the target of (over voltage stall).
Under vector control, unusual noise may be generated from the motor during deceleration
when using regeneration avoidance function. To prevent this, make gain adjustment, e.g. by
performing easy gain tuning. (Refer to section 6.3.3)
FR-A700 EC
Restriction level
Output frequency
Pr. 885
Pr. 885/2
Time
Fig. 6-263:
Limit the output frequency
Special operation
I001260E
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