Hitachi SJ Series User Manual page 333

Chapter 12
12.14.4 Starting with frequency pull-in
Q
• How to start operation by quickly following the
frequency command regardless of the frequency at
which the motor is idling
• How to quickly follow the frequency command at
the time of a trip retry, free-run stop, reset,
power-on, etc.
A
• To achieve these goals when the motor is idling
due to a trip or terminal function, enable the
frequency pull-in function so that the inverter is
started with the output frequency specified to each
function.
• Even if a motor residual voltage is lost, the inverter
will restart at the frequency selected in [bb-47] Start
frequency selection for frequency pull-in restart.
(Ex.) How the frequency pull-in works
Power failure
factor
Output current
Inverter output
frequency
Free-running
Motor speed
Lower limit
setting
[bb-42]
Retry wait time
Parameter
Item
Frequency matching
lower limit setting
Frequency pull-in
restart level
Frequency pull-in
operation time
(frequency)
Frequency pull-in
operation time
(voltage)
Overcurrent
suppression level for
frequency pull-in restart
Start frequency
selection for frequency
pull-in restart
Frequency pull-in
restart level
[bb-43]
Deceleration time set at [bb-44]
Frequency set at [bb-47]
Restarting with frequency pull-in
Parameter
[bb-42] 0.00~590.00(Hz)
[bb-43] Inverterrated current × (0.20 to 2.00)
[bb-44] 0.10~30.00(s)
[bb-45] 0.10~30.00(s)
[bb-46] Inverterrated current × (0.00 to 2.00)
00
[bb-47] 01
02
!
• If the restart after free-run stop or the restart after
reset is performed, the inverter will restart after the
retry wait time after instantaneous power
failure/under-voltage has elapsed.
• The restart after free-run stop and the restart after
reset will be performed when the operation
command is given.
• The frequency pull-in restart function can be used
only for induced motor drive. In addition, if [AA121]
Control mode is set to other than the V/f control,
restart may become unstable. In this case, see
"12.14.3 Starting by picking up frequency".
• When frequency pull-in with the V/f control is
selected, the inverter starts with a suppressed
output voltage during the time set for [bb-45]
Frequency pull-in operation time (voltage). When
sensorless vector control, zero-speed range
sensorless vector control, or vector control with
sensor is selected, the frequency is automatically
pulled in while controlling the current.
• If the current increases during frequency pull-in to
exceed [bb-43] Restart level, the motor will
decelerate over the time set for [bb-44] Frequency
pull-in operation time (frequency).
• If the current rapidly increases during frequency
pull-in to exceed [bb-46] Overcurrent suppression
level for frequency pull-in restart, the overcurrent
suppression function will automatically set in.
Data
12-14-6
Inverter Function
Description
When the detected value is equal to or
lower than the set value, the inverter
restarts with 0 Hz.
Determines whether or not the current
has increased at restart.
Sets the deceleration time for an
increase in the current.
Sets the time to start with reduced
output voltage.
Sets the level of the current at which a
sudden current increase at restarting
is prevented.
Starts at the frequency at the previous
shutoff.
Starts at the maximum frequency.
Starts at the current frequency
command.