BEKA BA337E, Manual

Page: 26 / 61

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 BA337E and the BA338E 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.
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