Contents

Protective and Diagnostic Functions
Table 6.20 Resetable Faults
Display Meaning Probable Causes Corrective Actions
UV1
DC Bus Undervolt
DC Bus Undervoltage
The DC bus voltage is below the Undervoltage
Detection Level
(L2-05). The default settings are:
200V class: 190 VDC
400 V class: 380 VDC
The voltage fluctuations of the power
supply are too high.
A momentary power loss occurred.
The terminal screws of the input
power supply are loose.
An open-phase error occurred at the
input terminals.
The acceleration time is set too short.
Check the input voltage.
Check the wiring of the input terminals.
Check the input voltage and the
wiring of the input terminals.
Extend the settings in
C1-01/03/05/07
Main Circuit MC
Operation Failure
The MC stopped responding during
Inverter operation.
An error occurred in the inrush current
prevention circuit while the Inverter
was running.
Replace the Inverter.
UV2
CTL PS Undervolt
UV3
MC Answerback
Control Power Supply
Undervoltage
Undervoltage of the control circuit
while the Inverter was running.
Inrush Current Prevention Circuit
Fault
An overheating of the charging resistor
for the DC bus capacitors
occurred.
The MC of the charging circuit did not
respond 10 sec. after the MC ON signal
has been output.
(Applicable Inverter Capacities
200 V class: 37 to 110 kW
400 V class: 75 to 300 kW)
External load was pulling down the
Inverter’s power supplies or there was
an internal short in the power/gate
drive board.
The contactor of the inrush current
prevention circuit is defective.
Remove all connection to the control
terminals and cycle the power
to the Inverter.
Replace the Inverter.
Cycle the power to the Inverter.
Replace the Inverter if the fault
continues to occur.
6
The wiring terminals for the input
power supply are loose.
Tighten the input terminal screws
PF
Input Phase Loss
Main Circuit Voltage Fault
An unusual big ripple on the DC bus
voltage has been detected.
Only detected when L8-05=1
(enabled)
A phase loss occurred in the input
power supply.
A momentary power loss occurred
The voltage fluctuations in the input
power supply are too high.
Check the power supply voltage
The voltage balance between the input
phases is bad.
LF
Output Phase Loss
Output Open-phase
An open-phase occurred at the
Inverter output.
The fault is detected when the output
current falls below 5% of the inverter
rated current and L8-07=1 (enabled)
There is a broken wire in the output
cable.
There is a broken wire in the motorwinding.
The output terminals are loose.
The motor being used has a capacity
less than 5% of the Inverter's maximum
motor capacity.
Reset the fault after correcting its
cause.
Check the motor and Inverter
capacity.
6-3