Mitsubishi Electric FR-A700 Technical Manual page 260

(5) Torque bias operation [Pr. 844, Pr. 845]
When [Pr. 844 Torque bias filter ≠ 9999], you can slow
the rise of torque. At this time, the torque rises
according to the time constant of the primary delay
filter.
primary delay time
* When not performing pre-excitation, the torque bias functions simultaneously with the start signal.
2.9.6 Speed limit [Pr. 285, 853, 873]
This function prevents the motor from overrunning when the load torque is too large and incorrect number of encoder is set.
[Pr. ] Name
Speed deviation excess
285
detection frequency
853
Speed deviation time
873
Speed limit
*1 Acts as over speed detection frequency under encoder feedback operation. (Refer to page 392)
(1) Speed deviation excessive [Pr. 285, 853]
When the deviation between the set frequency and
actual speed is large, e.g. too large load torque, this
function can cause the inverter to provide a speed
deviation excessive fault (E.OSD) and come to trip.
Fault output
(across A-C)
Speed
Torque bias
Torque bias filter
constant
Output torque
Time when torque is
generated by
torque bias setting
Pre-excitation LX
*
Start signal
Initial Value
9999
*1
1.0s
20Hz
Set frequency
[Pr. 285]
Actual speed
Time
[Pr. 853]
OFF ON
Speed deviation
excessive fault activated
(E. OSD)
Set the time for output torque be maintained with the
torque bias command value alone in [Pr. 845 Torque
bias operation time] .
[Pr. 844]
[Pr. 845]
A700
(A700)
Setting Range
9999 Without speed deviation excessive
0 to 30Hz If the difference (absolute value) between the speed
command value and actual speed exceeds the [Pr. 285
Speed deviation excess detection frequency] setting for
0 to 100s longer than the time set in [Pr. 853 Speed deviation time],
speed deviation excessive occurs and error "E. OSD"
appears, resulting in a stop.
0 to 120Hz Frequency is limited at the set frequency + [Pr. 873].
(2) Speed limit [Pr. 873]
This function prevents the motor from overrunning
when the setting of number of encoder pulses and
the actual number differ.
When the setting of number of encoder pulses is
smaller than the actual number, the motor may
increase its speed. To prevent this, restrict the output
speed by the frequency(set frequency and [Pr. 873]).
Actual speed
at error occurrence
294
PARAMETER
Description
Set speed + [Pr. 873] value
Value of [Pr. 873]
Set speed
Speed during
normal operation.