Fuji Electric FRENIC-HVAC User Manual page 371

• When the power is restored, the inverter will wait 2 seconds for input of a run
command. However, if the allowable momentary power failure time (H16) has
elapsed after the power failure was recognized, the inverter will no longer wait 2
seconds for input of a run command and start operation in the normal starting
sequence.
• If the terminal command BX ("Coast to a stop") is entered during the power
failure, the inverter gets out of the restart mode and enters the normal running
mode. When a run command is entered with power supply applied, the inverter
will start from the normal starting frequency.
• The inverter recognizes a momentary power failure by detecting an undervoltage
condition when the voltage of the DC link bus goes below the lower limit. In a
configuration where a magnetic contactor is installed on the output side of the
inverter, the inverter may fail to recognize a momentary power failure because
the momentary power failure shuts down the operating power of the magnetic
contactor, causing the contactor circuit to open. When the contactor circuit is
open, the inverter is cut off from the motor and load so that the voltage drop in the
DC link bus may not be great enough to be recognized as a power failure. In such
an event, the restart after a recovery from momentary power failure does not
work properly as designed. To solve this, connect the auxiliary contact of the
magnetic contactor to the inverter terminal which the IL ("Interlock") is assigned
to so that a momentary power failure can sure be detected.
 For details about IL, refer to E01 to E07 (data = 22).
IL
OFF
ON
During a momentary power failure, the motor slows down. After power is restored, the
inverter restarts at the frequency just before the momentary power failure. Then, the current
limiting function works and the output frequency of the inverter automatically decreases.
When the output frequency matches the motor speed, the motor accelerates up to the original
output frequency. See the figure below. In this case, the instantaneous overcurrent limiting
must be enabled (H12 = 1).
• Auto-restarting after momentary power failure IPF
This output signal is ON during the period after the occurrence of momentary power failure
until the completion of a restart sequence (until the output reaches the reference frequency).
When the IPF is ON, the motor slows down, so perform necessary operations.
 For details about IPF, refer to E01 through E07 (data = 6).
6.3 Details of Function Codes
Description
No momentary power failure has occurred.
A momentary power failure has occurred. (Restart
after a momentary power failure enabled)
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