8-3
Fault Display Probable causes and remediesMeaning
SC
Short Circuit
The Inverter output or load was
short-circuited.
• A short-circuit or ground fault occurred at the In-
verter output. (A short or ground fault can be
caused
by motor burn damage, worn insulation,
or
a damaged cable.)
→ Reset the fault after correcting its cause.
OV
Overvoltage
The main circuit DC voltage
exceeded the overvoltage
detection level.
200-V class: Approx. 400 V
400-V class: Approx. 800 V
• The deceleration time is too short and the regen-
erative energy from the motor is too large.
→ Increase the deceleration time or connect a
braking resistor (or Braking Resistor Unit).
• A surge is generated when the phase-advancer
condenser switches.
→ Add an AC reactor to the power supply input.
• The power supply voltage is too high.
→ Decrease the voltage so it’s within specifica-
tions.
UV1
DC Bus Undervolt
The main circuit DC voltage is
below the undervoltage
detection level (L2-05).
200-V class: Approx. 190 V
400-V class: Approx. 380 V
• A
phase loss occurred with the
input power supply
.
• A momentary power interruption occurred.
• The
wiring terminals for the input power supply are
loose.
• The voltage fluctuations in the input power supply
are too large.
→ Reset the fault after correcting its cause.
UV2
CTL PS Undervolt
The control power supply
voltage dropped.
→ Try turning the power supply off and on.
→ Replace
the
Inverter if the fault continues to oc
-
cur.
UV3
MC Answerback
A failure occurred in the inrush
prevention circuit.
→ Try turning the power supply off and on.
→ Replace
the
Inverter if the fault continues to oc
-
cur.
PF
Input Pha Loss
The main circuit DC voltage
oscillates unusually (not when
regenerating).
This fault is detected when
L8-05 is set to “Enabled.”
• A phase loss occurred in the input power supply.
• A momentary power interruption occurred.
• The
wiring terminals for the input power supply are
loose.
• The voltage fluctuations in the input power supply
are too large.
• The voltage balance between phases is bad.
→ Reset the fault after correcting its cause.
• The main circuit smoothing condenser has ex-
ceeded its life expectancy.
→ Replace the electrolytic condenser.
(Contact your OMRON representative.)
Maintenance Operations Chapter
8