5-47
If H16 (Allowable momentary power failure time) is set to "999," restart will take place until the DC link bus voltage
drops down to the allowable voltage for restart after a momentary power failure (50 V for 200 V class series and 100 V
for 400 V class series). If the DC link bus voltage drops below the allowable voltage, the inverter recognizes that the
power has been shut down so that it does not restart but starts (normal starting).
Power supply voltage Allowable voltage for restart after momentary power failure
200 V class series 50 V
400 V class series 100 V
The time required from when the DC link bus voltage drops from the threshold of undervoltage until it
reaches the allowable voltage for restart after a momentary power failure, greatly varies depending on the
inverter capacity, the presence of options, and other factors.
Restart mode after momentary power failure (Restart time) (H13)
H13 specifies the time period from momentary power failure occurrence until the inverter reacts for restarting process.
If the inverter starts the motor while motor’s residual voltage is still in a high level, a large inrush current may flow or
an overvoltage alarm may occur due to an occurrence of temporary regeneration. For safety, therefore, it is advisable to
set H13 to a certain level so that the restart will take place only after the residual voltage has dropped to a low level.
Note that even when power is restored, restart will not take place until the restart time (H13) has elapsed.
Factory default: By factory default, H13 is set to the value suitable for the standard motor (see Table B in Section 5.1
"Function Code Tables"). Basically, it is not necessary to change H13 data. However, if the long restart time causes the
flow rate of the pump to overly decrease or causes any other problem, you might as well reduce the setting to about a
half of the default value. In such a case, make sure that no alarm occurs.
Function code H13 (Restart mode after momentary power failure -- Restart time) also applies to the switching
operation between line and inverter (refer to the descriptions of E01 through E07).
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