BEKA BA354E, Руководство пользователя

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1. DESCRIPTION
The BA354E is an intrinsically safe 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
BA354E 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.
The rate totaliser has been certified intrinsically
safe for use in gas and dust hazardous areas by
Notified Body Intertek Testing and Certification Ltd
and complies with the European ATEX Directive
94/9/EC. Dust certification is an option described
in Appendix 1 which must be requested when the
instrument is ordered. The EC-Type Examination
certificate specifies that under fault conditions the
output voltage, current and power at the 4/20mA
input terminals will not exceed those specified for
simple apparatus in Clause 5.7 of EN 60079-11,
which simplifies installation and documentation.
For international applications the BA354E has
IECEx certification - described in Appendix 2.
Housed in a robust IP66 glass reinforced polyester
(GRP) enclosure with an armoured glass window,
the BA354E 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
BA354E. 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.
Fig 1 Simplified block diagram of BA354E
2.1 Controls
The BA354E 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 –
Initially
displays most significant 8
digits.
After 10 seconds grand total may be
reset to zero. Configurable function.
▼ + ▲ Resets total display
Configurable function
P+▼ Show firmware version
P+▲ Alarm setpoint access
Configurable function
P+E Access to configuration menu
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