Hitachi SJ Series, User Manual

Page: 333 / 786

12-14-6
Chapter 12 Inverter Function
12.14.4 Starting with frequency pull-in
• 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.
• 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
Parameter
• 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.
Item Parameter Data Description
Frequency matching
lower limit setting
[bb-42] 0.00~590.00(Hz)
When the detected value is equal to or
lower than the set value, the inverter
restarts with 0 Hz.
Frequency pull-in
restart level
[bb-43] Inverterrated current × (0.20 to 2.00)
Determines whether or not the current
has increased at restart.
Frequency pull-in
operation time
(frequency)
[bb-44] 0.10~30.00(s)
Sets the deceleration time for an
increase in the current.
Frequency pull-in
operation time
(voltage)
[bb-45] 0.10~30.00(s)
Sets the time to start with reduced
output voltage.
Overcurrent
suppression level for
frequency pull-in restart
[bb-46] Inverterrated current × (0.00 to 2.00)
Sets the level of the current at which a
sudden current increase at restarting
is prevented.
Start frequency
selection for frequency
pull-in restart
[bb-47]
00
Starts at the frequency at the previous
shutoff.
01 Starts at the maximum frequency.
02
Starts at the current frequency
command.
Q
A
!
Retry wait time
Free-running
Power failure
factor
Inverter output
frequency
Motor speed
Lower limit
setting
[bb-42] Restarting with frequency pull-in
Output current
Frequency pull-in
restart level
[bb-43]
Frequency set at [bb-47]
Deceleration time set at [bb-44]