5.3 Description of Function Codes
5-68
■ Restart mode after momentary power failure (Basic operation: Without auto-searching setting)
When inverter detected that DC link bus voltage becomes at or drops below undervoltage level while operating, it
is judged as a momentary power failure. When load is light and momentary power failure is very short, momentary
power failure may not be detected and motor operation might be continued because DC link bus voltage does not
drop so much.
When inverter judges the state as momentary power failure, returns to momentary power failure restart mode and
prepares for restart. After power is auto-restarted, the inverter becomes at inverter ready to run state after elapse
of initial charging time. At momentary power failure, power of external circuit (relay circuit etc.), which controls the
inverter, decreases as well, and run command may be turned off. Therefore, when the inverter becomes at inverter
ready to run state, wait 2 seconds for input of run command. When input of run command is confirmed within 2
seconds, initiate restarting according to F14 (mode selection). When there is no input of run command at run
command input waiting state, momentary power failure restart mode will be released and start from normal starting
frequency. Therefore, input run command within 2 seconds after auto-restarting or hold run command by off-delay
timer or mechanical latch relay.
In case of F02=0 (run command from keypad and rotation direction command determined by terminal), it operates
in the same way as above. For rotation direction fixed mode (F02 = 2, 3), run command is held within the inverter,
therefore, it restarts immediately at inverter ready to run state.
• 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 a 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 whi
ch 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. T
herefore, 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 E05 Data = 22
Terminal command “IL” Meaning
OFF No momentary power failure has occurred.
ON
A momentary power failure has occurred.
(Restart after a momentary power failure enabled)
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