Mitsubishi Electric 800 Series Instruction Manual page 34

Check
point
Two-wire or three-wire type connection is
incorrect.
Under V/F control, Pr.0 Torque boost
setting is not appropriate.
Pr.78 Reverse rotation prevention
selection is set.
The Pr.79 Operation mode selection
setting is incorrect.
The bias and gain (the calibration
parameter C2 to C7) settings are not
appropriate.
The Pr.13 Starting frequency setting is
greater than the set frequency.
Zero is set in frequency settings (such as
for multi-speed operation).
Especially, Pr.1 Maximum frequency is
zero.
Pr.15 Jog frequency is lower than Pr.13
Starting frequency for JOG operation.
Parameter
Operation mode and a writing device do
setting
not correspond.
The start signal operation selection is set
by Pr.250 Stop selection
The motor has decelerated to a stop
when the power failure time deceleration-
to-stop function is selected.
Auto tuning is being performed.
The automatic restart after instantaneous
power failure function or power failure
stop function has been activated.
(Performing overload operation during
input phase loss may cause voltage
insufficiency, and that may result in
detection of power failure.)
The motor test operation is selected
under PM sensorless vector control.
Load is too heavy.
Load
The shaft is locked.
33
2. Protective Functions
2.6 Check first when you have a trouble
Possible cause
Check the connection.
Use the Start self-holding selection (STP (STOP)) signal when the three-wire type
is used.
Increase the 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 suitable for the input methods of the start command and
frequency command.
Check the bias and gain (the calibration parameter C2 to C7) settings.
Set the frequency higher than the one set in Pr.13.
The inverter does not start if the frequency setting signal has a value lower than that
of Pr.13.
Set the frequency command according to the application. Set Pr.1 higher than the
actual frequency used.
The Pr.15 setting should be equal to or higher than the Pr.13 setting.
Check Pr.79 Operation mode selection, Pr.338 Communication operation
command source, Pr.339 Communication speed command source, Pr.550
NET mode operation command source selection and Pr.551 PU mode
operation command source selection, and select an operation mode suitable for
the purpose.
Check the Pr.250 setting and the connection of the STF/DI0 and STR/DI1 signals.
When power is restored, ensure the safety, and turn OFF the start signal once, then
turn ON again to restart. When Pr.261 Power failure stop selection = "2", the
motor automatically restarts after the power is restored.
When offline auto tuning ends, press the STOP/RESET key on the operation panel
during PU operation. For the External operation, turn OFF the start signal (STF/DI0
or STR/DI1).
This operation resets the offline auto tuning, and the PU's monitor display returns to
the normal indication.
(Without this operation, next operation cannot be started.)
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 function was activated during acceleration.
Check the Pr.800 Control method selection setting.
Reduce the load.
Inspect the machine (motor).
Countermeasure