Instruction manual

8. Fault Diagnosis
171
Protective
Operation
Output is
turned OFF
and motor
coasts to a
stop.
PF (Main circuit voltage
fault)
The main circuit’s DC voltage
oscillated in an irregular way
when not in regenerative op-
eration.
• Open phase of input
supply
• Momentary power loss
• Excessive fluctuation in
input supply voltage
• Unbalanced line voltage
⇓
Check the following:
• Main circuit power sup-
ply connections
• Power supply voltage
• Terminal screws:
Loose?
LF (Output open phase)
An open phase occurred in
Inverter output.
• Disconnection in output
cable
• Disconnection in motor
windings
• Loose output terminal
screws
⇓
Check the following:
• Disconnection in output
wirings
• Motor impedance
• Terminal screws:
Loose?
UL3 (Undertorque de-
tection)
When V/f mode is selected:
The Inverter’s output current
was less than the Under-
torque Detection Level
(n118).
When vector mode is select-
ed:
The output current or output
torque was less than the de-
tection level (n097 to n118).
Operation when undertorque
is detected will be determined
by the setting in n117.
• Check the setting in
n118.
• Check the operating
conditions, and remove
the cause.
Fault Display Inverter
Status
Description Causes and Corrective
Actions
Digital
Operator
RUN (Green)
ALARM (Red)