Fuji Electric FRENIC-HVAC User Manual page 374

Restart mode after momentary power failure (Restart time) (H13)

H13 specifies the time period from an occurrence of a momentary power failure until the
restart of the inverter. (When auto search is enabled, H46 (Auto search delay time 2) applies.)
If the inverter starts the motor while motor's residual voltage is still in a high level, a high
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 A given
in Section 6.2 "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.
The restart time specified by H13 also applies to the switching operation (terminal
commands ISW50/ISW60) between line and inverter. Refer to E01 through E07
(data = 40, 41) for terminals [X1] to [X7].
Restart mode after momentary power failure (Frequency fall rate) (H14)

During restart after a momentary power failure, if the inverter output frequency and the idling
motor speed cannot be harmonized with each other, an overcurrent will flow, activating the
overcurrent limiter. If it happens, the inverter automatically reduces the output frequency to
match the idling motor speed according to the reduction rate (Frequency fall rate: Hz/s)
specified by H14.
Data for H14
Inherit
0.01 to 100.00 (Hz/s)
Auto
If the frequency fall rate is too high, regeneration may take place at the moment the
motor speed matches the inverter output frequency, causing an overvoltage trip. On
the contrary, if the frequency fall rate is too low, the time required for the output
frequency to match the motor speed (duration of current limiting action) may be
prolonged, triggering the inverter overload prevention control.
Inverter's action for the output frequency fall
Fall frequency with the selected deceleration time
Follow the frequency fall rate specified by H14
Follow the setting of the PI processor in the current limiter.
(The PI constant is prefixed inside the inverter.)
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