8. CALIBRATION EXAMPLES
This section contains two examples illustrating how
a BA354NE Rate Totaliser may be configured and
calibrated to display the rate of flow and total flow
measured by a flow meter with a 4/20mA output.
Section 8.1 describes the preferred method of
calibration using an external traceable 4/20mA
calibrator. Section 8.2 contains an example of
calibration using the BA354NE internal 4 and 20mA
references, which although not traceable, are
adequate for many industrial applications.
8.1 Using an external current source
In this example the BA354NE Rate Totaliser is
connected to a flowmeter having a linear output of
20mA at a flow of 1100 litres / minute. The
BA354NE is required to display flow in litres per
minute with a resolution of 1 litre and total flow in
cubic metres with a resolution of 0.1 cubic metres.
Total is to be shown on the upper large display and
rate on the lower smaller display. Totalisation is to
occur for flow rates between 1 and 100% of
maximum flow. A security code of 1209 is required.
In the operating mode the BA354NE is required to
display the input current as a percentage of span
when the
P
push button is operated. Local resetting
of the total display to zero is required.
Step 1
Connect instrument to calibrator
Connect the BA354NE to an accurate
current source such as a calibrator.
Terminal 1 positive and terminal 3
negative. The instrument will perform the
initialisation routine described in section
2.
Step 2
Enter the configuration menu
With an input current between 4 and
20mA put the instrument enter the
configuration menu by simultaneously
pressing
P
and
E
.
Assuming a security
code has not already been entered the
instrument will respond by displaying
'FunC' which is the first function in the
configuration menu.
Step 3
Select Rate Totaliser function
The flowmeter has a linear 4/20mA
output so neither the root extractor or the
lineariser are required. The standard
linear relationship should therefore be
selected. With 'FunC' displayed, press
P
which will reveal the existing function.
Using the
▼
or
▲
button select 'Std'.
Press
E
to enter this selection and return
to the 'FunC' prompt in the configuration
menu.
Step 4
Define function of
P
push-button
Select 'C--P' from the configuration menu
and press
P
to reveal the function of the
P
button in the operating mode. Select
percentage 'PC' and return to the
configuration menu by pressing
E
.
Step 5
Define rate display resolution
Maximum rate display resolution is
required. Select 'rE5n' from the main
menu and press
P
to reveal the current
resolution of the rate display. Using the
▼
and
▲
push buttons select a
resolution of '1' and return to the 'rE5n'
prompt in the configuration menu by
pressing
E
.
Step 6
Rate and total display location.
The upper display is required to show the
total flow. Select 'di5P-1' from the
configuration menu and press
P
to reveal
the current upper display variable. Using
the
▼
and
▲
push buttons select ‘totAL’
and return to the 'di5P-1' prompt in the
configuration menu by pressing
E
.
The lower display is required to show the
flow rate. Select 'di5P-2' from the
configuration menu and press
P
to reveal
if this display is activated. Using the
▼
and
▲
push buttons select ‘on’ and
return to the 'di5P-2' prompt in the
configuration menu by pressing
E.
Step 7
Position rate & total decimal points
Select ‘dP’ from the configuration menu
and press
P
. The upper display will be
activated and will show the total display.
Press the
▲
or
▼
push button to position
the decimal point in front of the least
significant digit of the display. This gives
the required total display resolution of 0.1
Press
P
to change the upper display from
total to rate. Using the
▲
or
▼
push
button move the decimal point to the right
hand side of the least significant digit
where it is not displayed. This gives the
required rate display resolution of 1 litre
with no decimal point visible.
Finally press
E
to return to the 'dP’
prompt in the main menu.
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