Mitsubishi Electric FR-A720-0.4K Instruction Manual page 431

Check first when you have a trouble
Check
points
was pressed.
(Operation panel indication is
Two-wire or three-wire type connection is wrong.
Pr. 0 Torque boost setting is improper when V/F control is
used.
Pr. 78 Reverse rotation prevention selection is set.
Pr. 79 Operation mode selection setting is wrong.
Bias and gain (calibration parameter C2 to C7) settings
are improper.
Pr. 13 Starting frequency setting is greater than the
running frequency.
Frequency settings of various running frequency (such
as multi-speed operation) are zero.
Especially, Pr. 1 Maximum frequency is zero.
Pr. 15 Jog frequency setting is lower than Pr. 13 Starting
frequency.
The Pr.359 Encoder rotation direction setting is incorrect
Parameter
under encoder feedback control or under vector control.
Setting
Operation mode and a writing device do not match.
Start signal operation selection is set by the Pr. 250 Stop
selection
Inverter decelerated to a stop when power failure
deceleration stop function is selected.
Auto tuning is being performed.
Automatic restart after instantaneous power failure
function or power failure stop function is activated.
(Performing overload operation during input phase loss
may cause voltage insufficiency, and that may result in
detection of power failure.)
Load is too heavy.
Load
Shaft is locked.
420
Possible Cause
(PS).)
Countermeasures
During the External operation mode, check the method of
restarting from a input stop from PU.
Check the connection.
Connect STOP signal when three-wire type is used.
Increase Pr. 0 setting by 0.5% increments while observing
the rotation of a motor.
If that makes no difference, decrease the setting.
Check the Pr. 78 setting.
Set Pr. 78 when you want to limit the motor rotation to only
one direction.
Select the operation mode which corresponds with input
methods of start command and frequency command.
Check the bias and gain (calibration parameter C2 to C7)
settings.
Set running frequency higher than Pr. 13.
The inverter does not start if the frequency setting signal is
less than the value set in Pr. 13.
Set the frequency command according to the application.
Set Pr. 1 higher than the actual frequency used.
Set Pr. 15 Jog frequency higher than Pr. 13 Starting frequency.
If the "REV" on the operation panel is lit even though the
forward-rotation command is given, set Pr. 359 ="1."
Check Pr. 79, Pr. 338, Pr. 339, Pr. 550, Pr. 551, and select an
operation mode suitable for the purpose.
Check Pr. 250 setting and connection of STF and STR
signals.
When power is restored, ensure the safety, and turn OFF
the start signal once, then turn ON again to restart.
Inverter restarts when Pr. 261="2, 12".
In the PU operation, press
after the offline auto tuning completes.
In the External operation, turn OFF the start signal (STF,
STR).
By this operation, offline auto tuning is cancelled, and the
monitor display on the PU goes back to normal.
(If this operation is not performed, you cannot proceed to
the next operation.)
Set Pr. 872 Input phase loss protection selection = "1" (input
phase failure protection active).
Disable the automatic restart after instantaneous power
failure function and power failure stop function.
Reduce the load.
Increase the acceleration time if the automatic restart
after instantaneous power failure function or power
failure stop function occurred during acceleration.
Reduce the load.
Inspect the machine (motor).
Refer
to
page
406
236
146
308
313
294
175
157
167
38
313,
322
236
270
on the operation panel
189
266,
270,
276
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