Protective and Diagnostic Functions
7-
3
OV
DC Bus
Fuse Open
Main Circuit Overvoltage
The main circuit DC voltage exceeded
the overvoltage detection level.
200 V Class: Approx. 410 V
400 V Class: Approx. 820 V
The deceleration time is too short and
the regenerative energy from the
motor is too large.
Increase the deceleration time or
connect a braking resistor (or
Braking Resistor Unit). Alterna-
tively, enable (set to 1) the stall
prevention selection during decel-
eration (L3-04).
The regenerative energy when an
overshoot occurs after acceleration is
completed is too large.
In vector control, enable (set to 1)
the overvoltage inhibit selection
(L3-11).
The power supply voltage is too high.
Decrease the voltage so it’s within
specifications.
UV1
DC Bus
Undervolt
Main Circuit Undervoltage
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
• An open-phase occurred with the
input power supply.
• A momentary power loss 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
Control Power Fault
The control power supply voltage
dropped.
The wiring of the control power cir-
cuit is incorrect.
• Try turning the power supply
off and on.
• Replace the Inverter if the fault
continues to occur.
UV3
MC
Answer-
back
Inrush Prevention Circuit Fault
A fault occurred in the surge preven-
tion circuit.
• The MC in the main circuit failed.
• The MC excitation coil is burned
out.
• Try turning the power supply
off and on.
• Replace the Inverter if the fault
continues to occur.
PF
Input Pha
Loss
Main Circuit Voltage Fault
The main circuit DC voltage oscillates
unusually (not when regenerating).
This fault is detected when L8-05 is
set to “Enabled.”
• An open-phase occurred in the input
power supply.
• A momentary power loss 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.
LF
Output Pha
Loss
Output Open-phase
An open-phase occurred at the
Inverter output.
This fault is detected when L8-07 is
set to “Enabled.”
• There is a broken wire in the output
cable.
• There is a broken wire in the motor-
winding.
• The output terminals are loose.
Reset the fault after correcting its
cause.
The motor being used has a capacity
less than 5% of the rated output cur-
rent.
Check the motor and Inverter
capacity.
OH
(OH1)
Heatsnk
Overtemp
(Heatsnk
MAX
Temp)
Cooling Fin Overheating
The temperature of the Inverter's cool-
ing fins exceeded the setting in L8-02
or 105
°
C.
The ambient temperature is too high.
Install a cooling unit.
There is a heat source nearby.
Remove the heat source.
The Inverter's cooling fan has stopped.
Replace the cooling fan. (Contact
our sales representative.)
Inverter's Cooling Fan Stopped
(18.5 kW or higher)
The Inverter's cooling fan has stopped.
Table 7.1 Fault Displays and Processing (Continued)
Display
Meaning
Probable Causes
Corrective Actions