BEKA BA334NG, Manual

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6.15 Timebase:
t-bA5E
The timebase multiplies the rate display by 1, 60 or
3,600 depending upon whether the Rate Totaliser is
required to display rate per second, per minute or
per hour. See Fig 9.
To check or change the timebase, select
t-bA5E
from the configuration menu and press
(
which
will reveal the existing setting. Pressing the
&
or
*
button will scroll through the three options:
tb-1
for flow / second
tb-60
for flow / minute
tb-3600
for flow / hour
When the required multiplier is displayed press
)
to return to the
t-bA5E
prompt in the configuration
menu.
6.16 Display filter:
FiLtEr
The digital display filter has two independent
adjustable parameters enabling the rate display
response to be tailored for optimum performance.
The filter parameters are controlled by a two digit
number. The first digit defines the amount of
filtering applied to the display as shown below.
First
digit
Filter time constant
seconds
0X 0
1X 1.3
2X 4.3
3X 6.5
4X 8.7
5X 11.3
6X 15.7
7X 20.9
8X 25.2
9X 31.5
The second digit 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.
Second
digit
Magnitude of step
change which will
produce a rapid
response
X0 off
X1 1%
X2 2%
X3 4%
X4 8%
X5 12%
X6 16%
X7 24%
X8 32%
X9 64%
By careful adjustment of the two parameters a
stable display with an acceptable input step
response can be obtained for most applications.
During commissioning it is recommend that initially
the second digit is set to
0
(off) and the first digit is
adjusted to provide acceptable rate display
stability. The second digit 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 become stable. These will be the
optimum filter parameters for acceptable rate
display stability and a fast response to a large rate
signal change.
To check or change the filter select
FiLtEr
in the
configuration menu and press
(
which will reveal
the existing settings with the first digit flashing.
Pressing the
&

or

*
button will change the
flashing digit and
(
will transfer control to the
second digit. While making adjustments the
filtered rate display is shown on the lower display
so that stability can be assessed while adjustments
are being made. When set as required, press the
)
button to enter the revised parameters and
return to the
FiLtEr
prompt in the configuration
menu.
6.17 Clip-off:
CLP oFF
To prevent totalisation of very low flow rates that
over long periods may result in significant
totalisation errors, the BA334NG may be
configured to stop totalising when the flow rate falls
below an adjustable threshold.
To check or change the clip-off threshold select
CLP oFF
from the configuration menu and press
(
which will reveal the current setting. The threshold
is shown in the units already selected for the flow
rate display. One digit will be flashing. The value
of the flashing digit may be changed by pressing
the
&
or
*
button. When this digit is correct
pressing
(
will transfer control to the next digit.
When clip-off is set as required, press the
)
button to enter the revised figure and return to the
CLP oFF
prompt in the configuration menu.
When the flow rate falls below the clip-off
threshold, the rate display will show zero flow,
totalisation will stop and the HOLD annunciator will
be activated. The flow indicator will continue to
rotate for 2 seconds each time an input pulse is
received i.e. at input pulse frequencies above
0.5Hz it will appear to rotate continuously.
Note:
To avoid confusion, when the K-factor
FACtor
, rate
scale factor
5CALE . r
, timebase
t-bA5E
, or the
position of the rate display decimal point are
changed, clip-off will automatically be reset to zero.
A new clip-off threshold must therefore be entered
after any of these functions have been adjusted.