TROUBLE SHOOTING
7-11
3. “LU” Under voltage protection
Problem DC link circuit voltage was below the under voltage detection level.
What to Check and Suggested Measures
1. An instantaneous
power failure
occurred.
Reset the alarm.
→ If you want to restart running the motor without making the alarm
occur, set 4 or 5 to F14 depending on load.
2. The power inverter
was switched back on
too soon (with F14=1)
Check that you switch the inverter on after the power for the control
circuit had reached an appropriate level. This can be checked using
the display on the LED monitor.
→ Wait for a longer time than the last time before switching the
inverter on.
3. The power supply
voltage did not reach
the range of the
inverter’s
specifications.
Measure the input voltage.
→ Increase the voltage to within that of the specifications.
for the power circuit
malfunctioned, or the
connection was
incorrect.
Measure the input voltage to find where the peripheral equipment
malfunctioned or which connection is incorrect.
→ Replace any faulty peripheral equipment, or correct any incorrect
connections.
5. Other loads were
connected to the same
power system and
required a large
current to start running
to the extent that it
caused a temporary
voltage drop.
Measure the input voltage and check the voltage variation.
→ Reconsider the power system configuration.
6. Inrush current caused
the power voltage drop
because power
transformer capacity
was insufficient.
Check if the alarms occurs when you switch on a molded case circuit
breaker, an earth leakage circuit breaker (with the exception of those
exclusively designed for protection from ground faults) or a magnetic
contactor.
→ Reconsider the capacity of the power transformer.
4. “Lin” Input phase loss protection
Problem Input phase loss occurred, or interphase voltage unbalance rate was large.
Possible Causes What to Check and Suggested Measures
1. Main circuit power
input wires broken.
Measure the input voltage.
→ Repair or replace the wires.
2. The terminal screws
for the main circuit
power input were not
tight enough.
Check if the terminal screws have become loose.
→ Tighten the terminal screws to the recommended torque.
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