Hitachi CONVENTION 14 Instruction Manual page 128

B130, B131: Over-voltage LAD Stop Enable
/ Level – The over-voltage LADSTOP
function monitors the DC bus voltage and
actively changes the output frequency
profile to maintain the DC bus voltage
within settable limits. Although "LAD"
refers to "linear acceleration / deceleration",
the inverter only "STOPs" the deceleration
ramp so that regenerative voltage will not
cause the DC bus to rise enough to cause an
over-voltage trip
acceleration is not affected.
The graph at right shows an inverter
output profile that starts deceleration to a
stop. At two different points during the
deceleration, regenerative voltage elevates
the DC bus level, exceeding the LADSTOP
threshold set by B131.
When the Over-voltage LADSTOP feature is enabled by setting B130 = 01, the inverter
stops the deceleration ramp in each case until the DC bus level is again less than the
threshold value.
When using the Over-voltage LADSTOP feature, please note the following:
When the feature is enabled (B130 = 01), the actual deceleration is sometimes
longer than the value set by parameters F003/F203.
The over-voltage LADSTOP feature does not operate by maintaining a constant
DC bus voltage. So it is still possible to have an over-voltage trip event during
extreme deceleration.
If B131 is set
mistake, or if the inverter's input voltage increases enough, then the inverter will
apply LADSTOP (if enabled) all the time. In this case, the inverter can accelerate
and run the motor, but it cannot decelerate. If you are not sure that B131 > DC
bus voltage, measure the DC bus voltage in your installation and verify that the
B131 value is higher.
Func. Name /
Code SRW Display
B130 Over-voltage LADSTOP
enable
OVLADSTOP
B131 Over-voltage LADSTOP
level
LADST LVL 0 0380V
event. Note that
lower
than the normal DC bus voltage (when
"B" Function
Description
Pauses deceleration ramp when DC bus
voltage rises above threshold level, in
order to avoid over-voltage trip.
00 Disable
OFF
01 Enable
Sets the threshold level for over-voltage
LADSTOP. When the DC bus voltage is
above the threshold value, the inverter
stops deceleration until the DC bus
voltage is less than the threshold
setting again. Two voltage ranges with
1V resolution:
330 to 395V (200V class)
660 to 790V (400V class)
B130 = 01 OV LADSTOP = Enable
DC bus
voltage
B131
0
Output
frequency
Resumes decel
0
Set decel time (F003)
Actual decel time
Run
Mode
Edit
3 − 45
3 45
t
Stops decel
t
not
in decel) by
Defaults
-FE -FU
Units
(EU) (USA)
00 00
380/ 380/ V
760 760