8. CALIBRATION EXAMPLES
This section contains two examples illustrating how
a BA354E 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 BA354E 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 BA354E Rate Totaliser is
connected to a flowmeter having a linear output of
20mA at a flow of 1100 litres / minute. The
BA354E 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 BA354E 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 BA354E 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 '5td'. 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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