Hitachi X200 Series - Manual (Page 106)

“B” Group: Fine Tuning Functions
The “B” Group of functions and parameters adjust some of the more subtle but useful
aspects of motor control and system configuration.
Automatic Restart Mode
The restart mode determines how the inverter will resume operation after a fault
causes a trip event. The four options provide advantages for your applications.
Frequency matching allows the inverter to read the motor speed by virtue of its residual
magnetic flux and restart the output at the corresponding frequency. The inverter can
attempt a restart a certain number of times depending on the particular trip event:
• Over-current trip, restart up to 3 times
• Over-voltage trip, restart up to 3 times
• Under-voltage trip, restarts up to 16 time
When the inverter reaches the maximum number of restarts (3 or 16), you must power
cycle the inverter to reset its operation.
Other parameters specify the allowable under-voltage level and the delay time before
restarting. The proper settings depend on the typical fault conditions for your
application, the necessity of restarting the process in unattended situations, and
whether restarting is always say.
If the actual power fail time is
shorter than the B002 set value,
inverter resumes from the set
frequency in B011.
The resuming mode is called
“frequency pull-in” and the
inverter performs reduced voltage
start to avoid overcurrent trip.
If the motor current exceeds the
B030 set value during this period,
inverter decelerates according to
the B029 set value and helps to
reduce the motor current.
And when the motor current is
less than the B030, inverter
increases the motor speed again.
The performance continues this
retry action until the motor speed
comes to the previous set speed.
Overload restriction (B021~B028) is not valid when frequency pull-in is activated.
If the actual power fail time is longer than the B002 set value, the inverter does not
resume and the motor will coast to stop.
3−32
Confi
guri
ng Driv
e
Parameters
<Example>
Power failure < allowable power fail
time(B022), Inverter resumes
Free-running
Input
power
Inverter
output
Motor
rotation
B003
B002
Allowable power
fail time
Retry wait time
Power fail
Motor
current
B030 Freq. Pull-in restart level
B029
Freq. Pull-in restart
Deceleration constant