4-43
F14
Restart Mode after Momentary Power Failure (Mode selection)
H13 (Restart Mode after Momentary Power Failure (Restart time))
H14 (Restart Mode after Momentary Power Failure (Frequency fall rate))
H15 (Restart Mode after Momentary Power Failure (Continuous running level))
H16 (Restart Mode after Momentary Power Failure (Allowable momentary power failure time))
H92 (Continuity of running (P))
H93 (Continuity of running (I))
F14 specifies the action to be taken by the inverter (trip and restart) in the event of a momentary power failure.
Restart mode after momentary power failure (Mode selection) (F14)
• Under V/f control (F42 = 0 or 2)
Data for F14
Description
Auto search disabled
Auto search enabled
0: Trip immediately
As soon as the DC link bus voltage drops below the undervoltage detection level due to a
momentary power failure, the inverter issues undervoltage alarm
lu
and shuts down its output so
that the motor enters a coast-to-stop state.
1: Trip after recovery
from power failure
As soon as the DC link bus voltage drops below the undervoltage detection level due to a
momentary power failure, the inverter shuts down its output so that the motor enters a coast-to-stop
state, but it does not enter the undervoltage state or issue undervoltage alarm
lu
.
The moment the power is restored, an undervoltage alarm
lu
is issued, while the motor remains in a
coast-to-stop state.
2: Trip after
decelerate-to-stop
As soon as the DC link bus voltage drops below the continuous running level due to a momentary
power failure, decelerate-to-shop control is invoked. Decelerate-to-stop control regenerates kinetic
energy from the load's moment of inertia, slowing down the motor and continuing the deceleration
operation. After decelerate-to-stop operation, an undervoltage alarm
lu
is issued.
3: Continue to run
(for heavy inertia or
general loads)
As soon as the DC link bus voltage drops below the continuous running level due to a momentary
power failure, continuous running control is invoked. Continuous running control regenerates kinetic
energy from the load’s moment of inertia, continues running, and waits the recovery of power. When
an undervoltage condition is detected due to a lack of energy to be regenerated, the output
frequency at that time is saved, the output of the inverter is shut down, and the motor enters a
coast-to-stop state.
If a run command has been input,
restoring power restarts the inverter at the
output frequency saved when
undervoltage was detected.
If a run command has been input, restoring power
performs auto search for idling motor speed and
restarts running the motor at the frequency calculated
based on the searched speed.
This setting is ideal for fan applications with a large moment of inertia.
4: Restart at the
frequency at which
the power failure
occurred
(for general loads)
As soon as the DC link bus voltage drops below the undervoltage detection level due to a
momentary power failure, the inverter shuts down the output so that the motor enters a
coast-to-stop state.
If a run command has been input,
restoring power restarts the inverter at the
output frequency saved when
undervoltage was detected.
If a run command has been input, restoring power
performs auto search for idling motor speed and restarts
running the motor at the frequency calculated based on
the searched speed.
This setting is ideal for applications with a moment of inertia large enough not to slow down the
motor quickly, such as fans, even after the motor enters a coast-to-stop state upon occurrence of a
momentary power failure.
5: Restart at the
starting frequency
As soon as the DC link bus voltage drops below the undervoltage detection level due to a
momentary power failure, the inverter shuts down the output so that the motor enters a
coast-to-stop state.
If a run command has been input,
restoring power restarts the inverter at the
starting frequency specified by function
code F23.
If a run command has been input, restoring power
performs auto search for idling motor speed and restarts
running the motor at the frequency calculated based on
the searched speed.
This setting is ideal for heavy load applications such as pumps, having a small moment of inertia, in
which the motor speed quickly goes down to zero as soon as it enters a coast-to-stop state upon
occurrence of a momentary power failure.
Auto search is enabled by turning ON the digital terminal command
STM
("Enable auto search for idling motor speed at
starting") or setting the H09 data to "1" or "2."
For details about the digital terminal command
STM
and auto search, refer to the description of H09 (Starting Mode, Auto
search).