1. DESCRIPTION
The BA554E is a general purpose 4/20mA loop-
powered Rate Totaliser primarily intended for use
with flowmeters. The instrument simultaneously
displays the rate of flow and the total flow in
engineering units on two separate displays. The
BA554E only introduces a 1.2V drop which allows
it to be installed into almost any 4/20mA flow loop.
No additional power supply or battery is required.
Housed in a robust IP66 glass reinforced polyester
(GRP) enclosure with an armoured glass window,
the BA554E is surface mounting, or may be pipe
mounted using one of the accessory kits.
2. OPERATION
Fig 1 shows a simplified block diagram of a
BA554E. The 4/20mA input current flows through
resistor R1 and forward biased diode D1. The
voltage developed across D1, which is relatively
constant, is multiplied by a switch mode power
supply and used to power the instrument. The
voltage developed across R1, which is proportional
to the 4/20mA input current, provides the input
signal for the analogue to digital converter.
Each time a 4/20mA current is applied to the
instrument, initialisation is performed. After a short
delay the following display sequence occurs which
takes about twelve seconds:
All segments of the display are activated
Loading message displayed
Configuration message displayed
Model and firmware version displayed
Rate Totaliser starts functioning, using
configuration information stored in
instrument’s permanent memory. Unless
total and grand total displays have been
reset to zero, new flow will be added to
the existing totals.
If the 4/20mA current is disconnected during
operation the latest total and grand total are stored
in permanent memory.
Fig 1 Simplified block diagram of BA554E
2.1 Controls
The BA554E is controlled and calibrated via four
push buttons which are located behind the
instrument control cover, or as an option on the
outside of the instrument control cover. In the
operating mode i.e. when the instrument is
displaying rate and total flow the push button
functions are:
Summary of Push Button Functions
P
Displays input current in mA or as a
percentage of span. Modified when
optional alarms are fitted.
▼
Shows rate display calibration at 4mA
input.
▲
Shows rate display calibration at
20mA input.
E
Shows time since instrument was
powered or total display was reset.
E+
▼
Grand total –
displays least significant 8 digits
E+
▲
Grand total –
displays most significant 8 digits.
▼
+
▲
Resets
total
display
configurable function
P+
▼
Show firmware version
P+
▲
Access alarm setpoints
c
onfigurable function
P+E
Access to configuration menu
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