When The Motor Speed Is Unstable - Mitsubishi Electric FATEC FR-A800 Manual

5
BREAKDOWN MAINTENANCE
5.1.6

When the motor speed is unstable

The motor speed is unstable.
6-A
The speed is unstable.
fluctuation in the
vector control
YES
speed feedback
YES
Have vector
YES
related Pr.s been
adjusted?
NO
control used?
Adjust the related Pr.s.
Gain
Response level or
others
variation cycle
YES
Review the speed command.
Analog input
Deviation signal
command method
YES
Do RH, RM,
NO
and RL turn ON
simultaneously at
switching?
YES
Review the
fluctuation in the
multi-speed command
timing, and select the
speed setting.
setting correct?
The inverter is faulty.
Replace it with a substitute or
return it to the factory to repair.
Is the
speed large?
YES
NO
Is the
used?
NO
Is the
set?
Take countermeasures against the
noise.
NO
Install the cut core to the signal wire.
Increase the input filter time constant
T002 (Pr.74).
Magnetic flux vector
Is the V/F
Sensorless vector
NO
YES
Has auto
tuning been
performed?
YES
Is the
Perform offline
long?
auto tuning.
NO
YES
Is the speed
analog?
Is there
NO
any induction
noise?
Is the
multi-speed
command
used?
Is it
NO
improved after the
test operation
on PU?
NO
YES
Is there any
load?
NO
Check the load.
NO
Is the Pr.
YES
Set it again after
Pr. all clear.
Does OL
alarm occur?
NO
Does the
speed command
change?
Does the
YES
speed command
fluctuate?
NO
Is there any
fluctuation in the
load?
Is there any
fluctuation in the power
supply voltage?
NO NO
Is the Pr.
setting correct?
YES
YES
The inverter is faulty.
Replace it with a substitute
or return it to the factory to
NO
repair.
YES
Take countermeasures against the noise.
Install the cut core to the signal wire.
Increase the input filter time constant T002
(Pr.74).
Change to the digital speed command
method.
5.1 Troubleshooting
YES
4-A
Review the control.
YES
NO
Review the speed command.
Multi-speed/communication
Digital
Analog input
Deviation signal
YES
NO
Check the load.
YES
Set the base frequency voltage
G002 (Pr.19) to value other than
9999.
Review the power supply.
NO
Set it again after
Pr. all clear.
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