5.3 Description of Function Codes 5.3.1 F codes (Fundamental functions)
• At auto-restarting, inverters waits 2 seconds for input of run command, however, if allowable
momentary power failure time (H16) is elapsed after the state is judged as power failure, the state of
run command input waiting for 2 seconds will be canceled and normal starting operation is performed.
• When coast to stop command “BX” is entered during power failure, momentary power failure restart
waiting state is released and return to normal run mode, and when run command is inputted, start from
normal starting frequency.
• Detection of momentary power failure within the inverter is performed by detecting DC link bus voltage
drop of the inverter. With the structure in which a magnetic contactor is equipped on the output side of
the inverter, there will be no operation power of the magnetic contactor at momentary power failure
and the magnetic contactor becomes at open state. When the magnetic contactor becomes open,
connection of inverter and motor is released and load of the inverter is shutdown. Therefore, it becomes
difficult to decrease DC link bus voltage of the inverter and it may not be judged as a momentary power
failure. If this is the case, momentary power failure restart will not be performed normal. As a
countermeasure against this case, by connecting auxiliary contact signal of the magnetic contactor to
the interlock signal “IL” it is possible to detect momentary power failure without fail.
Function code E01 to E09 (data = 22)
No momentary power failure has occurred.
A momentary power failure has occurred.
(Restart after a momentary power failure enabled)
Restart mode after momentary power failure (mode selection)
When motor speed decreases during momentary power failure, and when restarting from frequency of before
momentary power failure after power is recovered (auto-restarting), current limiter becomes active and output
frequency of the inverter decreases automatically. When output frequency and motor rotation speed synchronize,
the speed is accelerated up to the original output frequency. Refer to the figure below. However, it is necessary to
enable instantaneous overcurrent limiting (H12 = 1) to bring in synchronization of the motor.
• Auto-restarting after momentary power failure “IPF”
During momentary power failure auto-restarting “IPF” signal is turned on until returning to original frequency after
auto-restarting after momentary power failure occurred. When “IPF”: is turned ON, motor speed decreases,
therefore, take necessary measures. ( Function codes E20 to E24, E27 (data = 6))
Output frequency
(motor rotational speed)
Auto-restarting after
momentary power failure IPF
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