Hitachi SJ Series User Manual page 330

Chapter 12
12.14.3 Starting by picking up frequency
Q
• How to start operation with the frequency matched
with the motor idling speed
• How to start operation matched with frequency at
the time of 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 matching function so that the inverter is
started by picking up frequency applied to each
function.
• Obtain the cycle of the motor residual voltage to
start operation.
• Frequency matching lower limit setting [bb-42] is
the parameter common to frequency matching
functions.
(Ex. 1) The motor speed is equal to or more than the
frequency matching lower limit setting.
Power failure
factor
Inverter output
Motor speed
Lower limit
setting
[bb-42]
Parameter
Item
Frequency matching lower
limit setting
!
• For the retry function, see "12.13 Using Trip
Avoidance Function" as well.
Free-running
Retry wait time
Restarting with frequency matching
Parameter
[bb-42] 0.00~590.00(Hz)
!
• Even if frequency matching restart is selected, the
inverter may restart with 0 Hz if:
1. the output frequency is equal to or lower than
1/2 of the base frequency,
2. the voltage induced on the induction motor
quickly attenuates, or
3. the frequency matching lower limit setting
[bb-42] is set and the inverter detects a
frequency equal to or lower than that.
• 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 if the operation command is
continuously input via a terminal command or other
ways.
• If the frequency matching restart does not go well
because the residual voltage rapidly decreases or
for other reasons, it may go well by using the
frequency pull-in restart. See "12.14.4 Starting with
frequency pull-in".
(Ex. 2) The motor speed is equal to or lower than the
frequency matching lower limit setting
Power failure
factor
Inverter
output
Motor speed
Lower limit
setting
[bb-42]
Data
When the detected value is equal to or
lower than the set value, the inverter
restarts with 0 Hz.
12-14-3
Inverter Function
Free-running
Retry wait time
Restart with 0 Hz
Description