Mitsubishi Electric FR-A820-00046 Instruction Manual page 874

(G) Control parameters
Feedback gain (Pr. 368)
● Set Pr. 368 "Feedback gain" when the rotation is unstable or response is slow.
● Response of the feedback will become slow when the acceleration/deceleration time is long. In
such case, increase the setting value of Pr. 368.
Pr. 368 setting
Pr. 368 > 1
1 > Pr. 368
Tab. 5-315: Setting of parameter 368
Overspeed detection (Pr. 285)
● To prevent malfunction when the correct pulse signal cannot be detected from the encoder, when
[detection frequency] – [output frequency] > Pr. 285
at the time of encoder feedback control, protective function (E.MB1) will activate and the inverter
will shutoff output.
● Overspeed detection is not performed when Pr. 285 = "9999".
NOTES Couple the encoder on the same axis as the motor axis without any mechanical clatter, with speed
ratio of 1:1.
Encoder feedback control is not performed during the acceleration and deceleration to prevent
the unstable phenomenon such as hunting.
Encoder feedback control is performed after the output frequency has reached [set frequency] ±
[speed feedback range] once.
When following status occurs at the time of encoder feedback control operation, inverter will not
stop with an alarm, and operate with output frequency of [set frequency] ± [speed feedback
range], and will not follow the speed of the motor.
● When the pulse signal from the encoder is lost due to a break, etc.
● When correct pulse signal cannot be detected due to induction noise, etc.
● When the motor is forcefully accelerated (regenerative rotation) or decelerated (motor lock)
due to large external force
Use the Inverter running (RUN) signal when releasing the brake from the motor with a brake. (The
brake may not be released when the Output frequency detection (FU) signal is used.)
Do not turn OFF the external power supply for the encoder at the time of encoder feedback con-
trol. Correct encoder feedback control will not be possible.
Parameters referred to
Pr. 81
5 - 694
Description
Response will become faster but it may cause overcurrent or become unstable.
Response will become slower but it will become more stable.
Number of motor poles
Parameters
=> page 5-56, page 5-67