B" Group: Fine Tuning Functions; Automatic Restart Mode - Hitachi WJ200 Series Instruction Manual

3−44

"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 five 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
When the inverter reaches the maximum number of restarts (3), 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.
Power failure < allowable power fail
Time (B022), Inverter resumes
Input
power
Inverter
output
Motor
current
Motor
rotation
Allowable power
fail time
Retry wait time
Overload restriction (B021~B028) is not valid when active frequency matching is
activated.
If the actual power failure time is longer than the B002 set value, the inverter does not
resume and the motor will coast to stop.
Restart level of active
freq. matching
Free-running
Power fail
Deceleration rate of active
B002
freq. matching
B003
If the actual power failure time is
shorter than the B002 set value,
inverter resumes from the set
frequency in B011.
The resumption mode is called
"active frequency matching" and
the inverter performs reduced
voltage start to avoid over-current
trip.
B030
If the motor current exceeds the
B030 set value during this period,
the inverter decelerates according
to the B029 set value and helps to
reduce the motor current.
When the motor current is less
than B030, the inverter increases
B029
motor speed toward the set speed.
The inverter continues this retry
process until the motor speed
comes to the previous set speed.