4-44
• Under vector control without speed sensor (F42 = 1 or 5)
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)
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 the F14 data is set to "3," the "Continue to run" function is disabled.
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.
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 d67 data to "1" or "2."
For details about the digital terminal command
STM
and auto search, refer to the description of d67 (Starting Mode, Auto
search).
• Under vector control with speed sensor (F42 = 6)
Data for F14
Description
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)
4: Restart at the
frequency at which
the power failure
occurred
(for general loads)
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 the F14 data is set to "3," the "Continue to run" function is disabled.
If a run command has been input, restoring power restarts the inverter at the motor speed
detected by the speed sensor.