8. Fault Diagnosis
101
Fault Display
Inverter
Status
Description
Causes and Correc-
tive Actions
Digital
Operator
RUN (Green)
ALARM (Red)
Protective Op-
eration
Output is
turned OFF
and motor
coasts to a
stop.
UV1 (Main circuit low
voltage)
Main circuit DC voltage
dropped below the low-
voltage detection level
while the Inverter output
is ON.
200 V: Stops at main cir-
cuit DC voltage
below approx. 200
V (160 V for sin-
gle-phase)
400 V: Stops at main cir-
cuit DC voltage of
approx. 400 V or
more
• Reduction
of
input
power supply voltage
• Open phase of input
supply
• Momentary
power
loss
⇓
Check the following:
• Power supply voltage
• Main circuit power
supply connections
• Terminal
screws:
Loose?
OH (Heatsink over-
heat)
Temperature increased
because of Inverter over-
load operation or intake
air temperature rise.
• Excessive
load
• Improper V/f pattern
setting
• Insufficient
acceleration time if
the fault occurs dur-
ing acceleration
• Intake air tempera-
ture exceeding 50
°
C
• Cooling
fan
stops.
⇓
Check the following:
• Load
size
• V/f pattern setting
(constants n09 to
n15)
• Intake air tempera-
ture.
OL1 (Motor over-
load)
Motor overload protec-
tion operated by built-in
electronic thermal over-
load relay.
• Check the load size
or V/f pattern setting
(constants n09 to
n15).
• Set the motor rated
current shown on the
nameplate in con-
stant n32.
OL2 (Inverter over-
load)
Inverter overload protec-
tion operated by built-in
electronic thermal over-
load relay.
• Check the load size
or V/f pattern setting
(constants n09 to
n15).
• Check the Inverter
capacity.
OL3 (Overtorque de-
tection)
Inverter output current ex-
ceeded the preset value
in constant n60.
When overtorque is de-
tected, Inverter performs
operation according to the
preset setting of constant
n59.
Check the driven machine
and correct the cause of
the fault, or increase the
value of constant n60 up
to the highest value al-
lowed for the machine.