GE Fuji Electric MICRO-SAVER AF-300, Startup Manual, Page: 87 / 127

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[3] LU Undervoltage protection
Problem Intermediate dc circuit voltage was below the undervolatge detection level.
Possible Causes What to Check and Suggested Measures
(1) An instantaneous power
failure occurred.
SUGGESTED ACTIONS
– Reset the alarm.
– To restart running the motor without an alarm, set F14 to a value of 4 or 5 depending on load.
2) The power to the drive
was switched back on
too soon (with F14 = 1)
CHECK
Only switch the drive on after the power for the control circuit has reached an appropriate level. This can
be checked using the display on the LED monitor.
SUGGESTED ACTIONS
– Wait longer before switching the drive on.
(3) The power supply voltage
did not reach the range of
the drive’s specifications.
CHECK
Measure the input voltage.
SUGGESTED ACTIONS
– Increase the voltage to specification.
(4) Peripheral equipment
for the power circuit
malfunctioned, or the
connection was wrong.
CHECK
Measure the input voltage to find where the peripheral equipment malfunctioned or which connection is
incorrect.
SUGGESTED ACTIONS
– Replace any faulty peripheral equipment, or correct any wrong connections.
(5) High inrush current of
other loads connected to
the same power system
as the drive caused a
temporary voltage drop.
CHECK
Measure the input voltage and check the voltage variation.
SUGGESTED ACTIONS
– Reconsider the power system configuration.
6) Inrush current caused the
power voltage drop be-
cause power transformer
capacity was insufficient.
CHECK
Check if the alarm occurs when you switch on a molded case circuit breaker, a ground fault circuit
interrupter (GFCI) or a magnetic contactor.
SUGGESTED ACTIONS
– Reconsider the power transformer rating.
[4] L Input phase loss protection
Problem Input phase loss occurred, or rate of unbalance of interphase power voltage was large.
Possible Causes What to Check and Suggested Measures
(1) Main circuit power input
wires broken.
CHECK
Measure the input voltage.
SUGGESTED ACTIONS
– Repair or replace the wires.
(2) The terminal screws for
the main circuit power
input were not tight
enough.
CHECK
Check if the terminal screws have become loose.
SUGGESTED ACTIONS
– Tighten the terminal screws to the recommended torque.
(3) Interphase unbalance
rate of 3-phase voltage
was too large.
CHECK
Measure the input voltage.
SUGGESTED ACTIONS
– Connect an ac reactor (ACR) or a dc reactor (DCR) to lower the rate.
– Raise the drive capacity.
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