5.1.11 When Oc Alarm Occurs - Mitsubishi Electric FATEC FR-A800 Manual

5
BREAKDOWN MAINTENANCE

5.1.11 When OC alarm occurs

Has it YES
occurred
at start?
NO
OC, OL alarm
Is the power YES
supply voltage
lowered?
Review the power
NO
supply system.
YES
Is it for the
vertical lift?
NO
Is the
stall prevention
Can the
YES H631 (Pr.154) set to
acceleration time
"0"?
be lengthened?
NO
Set the acceleration
time longer.
YES
Does an
instantaneous power
failure occur?
NO
Set the automatic restart after
instantaneous power failure
related Pr. correctly.
YES
Is MRS or RES
signal turned ON
and OFF?
Do not turn ON the MRS or
NO
RES signal during operation.
The inverter is faulty.
Replace it with a substitute or
return it to the factory to repair.
5.1 Troubleshooting
62
OC alarm occurs.
Has the load
changed suddenly?
mechanical cause be
considered?
YES
Does the
output MC turn ON
and OFF?
Operate the output MC correctly.
Do not turn ON or OFF the signal
during operation.
Have any
alarms not occurred
3-A
YES
been changed?
Check the changed Pr.
1
How much is
the OC value?
Accelerating
Is it for fans?
YES
NO
Set H631 (Pr.154) to "1".
The output voltage is lowered
during current control.
YES
power supply voltage
Set G002 (Pr.19) base
frequency voltage to value
other than 9999.
Review the power supply.
the Pr.s cleared?
YES
been changed?
The inverter is faulty.
Check the changed Pr.
Replace it with a substitute or
H500 (Pr.22): Stall prevention
G001 (Pr.3): Base frequency return it to the factory to repair.
YES
NO
Rail joint check
YES Reduction gear/wheel check
Can a
Mechanical looseness adjustment
NO
Has the
operating condition
been changed?
NO
NO
Has the
load condition
changed?
YES
NO
so far?
NO
Is it the
NO
conventional
model?
YES
Does OC
NO
occur repeatedly?
Has Pr.
YES
NO
Inverter life has finished.
Exchange it with the new one.
3
Decelerating
2
Constant speed
YES
NO
Is the
speed high?
NO
YES
NO
Is a reactor
Does the
installed?
fluctuate?
YES
Lower the base
NO
Remove the reactor. frequency voltage.
Are all
NO
YES
Clear all the Pr.s.
Has Pr.
NO
Can the
load be stabilized?
NO
Is the stall
YES
prevention operation level
H500 (Pr.22) set
correctly?
Review the operating
YES
condition.
YES
Check the motor type,
capacity, and whether
an error occurs.
Check the load.
Is the
YES
deceleration
time short?
F011 (Pr.8): Set the deceleration
NO
time longer.
Is the
YES
motor immediately
before a stop?
Check the output stop MRS signal and
NO
mechanical brake operation timing.
Check G000 (Pr.10) to G110 (Pr.12) that
are related to the DC injection brake
operation or others.
Is the
YES
stall prevention level
150% or less?
Increase the stall prevention level H500
NO
(Pr.22).
Be careful not to increase the level too
much because the OC alarm occurs.
Has it
occurred at a start or
during acceleration?
Power supply shut-off check
NO
MCCB, MC operation check
Does the
NO
brake resistance capacity
match the inverter?
Select the brake resistance not
YES
exceeding twice the inverter capacity.
Is it for
YES
the vertical
lift?
NO
Is the
load negative?
The inverter is faulty.
Replace it with a substitute or
return it to the factory to repair.
Increase the
brake capacity.
YES
Improve the load.
NO
Set H500 (Pr.22) stall
prevention correctly.
YES
NO
Select the magnetic
flux vector control.