BEKA BA458C, Manual

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6.6.6 Rate Filter
The BA458C contains a digital filter with two
independent adjustable parameters enabling
the rate display frequency response to be
tailored for optimum performance.
Smoothing
Amount of filtering applied (time constant).
Adjustable between 0 and 9, where 0 is no
filtering and 9 is maximum filtering.
Smoothing Filter time constant
seconds
0 0
1 1.3
2 4.3
3 6.5
4 8.7
5 11.3
6 15.7
7 20.9
8 25.2
9 31.5
Jump-Out
Defines the deviation from the displayed
rate at which the filter will be overridden
and the rate display will move rapidly to
the new value.
Jump-Out Magnitude of step
change which will
produce a rapid
response
0 Off
1 1%
2 2%
3 4%
4 8%
5 12%
6 16%
7 24%
8 32%
9 64%
By careful adjustment of the two parameters a
stable display with an acceptable step input
response can be obtained for most
applications.
During commissioning it is recommend that
initially Jump-Out is set to 0 (off) and
Smoothing is adjusted to provide acceptable
rate display stability. Jump-Out should then be
increased until the selected step size is greater
than the noise on the display signal, at which
setting the rate display will again become
stable. These will be the optimum filter
parameters for acceptable rate display stability
and a fast response to a large rate signal
change.
Smoothing: 2
Jump-Out: 4
1..9 = Light..Heavy /
1..9 = Fine..Coarse
6.6.7 Flow Alarm
The flow alarm may be assigned to any of the
batch controller outputs – See section 6.4.8
When the flow rate falls below the flow alarm
setpoint, the assigned output will close, the
BA458C will enter a pause condition and the
display will show ‘Paused – Low Flow’.
To prevent false alarms at the start of a batch
while the flow rate increases, the flow alarm
may be inhibited for between 1 and 3,600
seconds after the batch is started.
Low-Flow Rate
Inhibit Time
Flow Alarm
Highlight the ‘Low-Flow Rate’ option and
operate the P pushbutton, which will result in
the ‘Set Low-Flow Rate’ screen being
displayed with the decimal point positioned as
already specified. Set the required alarm
setpoint digit by digit then press E to enter the
value and return to the ‘Flow Alarm’ screen.
If the alarm is to be inhibited while the batch is
starting, highlight the ‘Inhibit Time’ option and
operate the P pushbutton which will result in
the ‘Inhibit: Seconds’ screen being displayed.
Set the required inhibit time digit by digit and
then press E to enter the value and return to
the ‘Flow Alarm’ screen.
6.6.8 Clip-Off
To prevent the batch total being incremented
at very low flow rates where flowmeters may
be less accurate, the BA458C incorporates an
adjustable clip-off function. At flow rates
below the adjustable clip-off threshold, the rate
display is forced to zero and the batch display
is not incremented.
00000.0
Set Clip-off Rate