4
2.2 Displays
The BA544D has two digital displays and
associated annunciators, plus a flow indicator
as shown on page 1.
Rate
Shows the flow rate on the
Display
smaller six digit display.
Total
Shows the total flow on the
display
larger eight digit display. Set
to zero when local or remote
reset switch is operated.
Flow
This disc in the lower left
indicator
hand corner of the display
'rotates' while input pulses are
being received. It will stop
rotating within two seconds of
the end of a display update
period in which no pulses were
received.
Hold
Activated when input
annunciator
frequency is below the clip-off
threshold.
Low battery
Battery symbol containing
Annunciator
word ‘LO’ is
a
ctivated when
internal battery requires
replacement.
2.3 Internal battery
The BA544D rate totaliser is powered by a
BA491 replaceable lithium battery that is
mounted within the instrument. This will
operate the BA544D for about five years, the
exact time depends upon how the instrument is
programmed and used, whether alarms are
fitted and the input pulse frequency. A low
battery alarm annuciator on the instrument
display will be activated when the battery
requires replacing. Normally the rate totaliser
will continue to operate for about five hundred
hours after the annunciator is activated, but the
exact time will depend upon how the
instrument is programmed, whether alarms are
fitted and the input frequency. During this
period the total and grand total will continue to
be transferred to permanent memory once per
hour. When the battery is exhausted the total
and grand total will be stored in permanent
memory, totalisation will stop and the
instrument will display ‘bAtt’.
3. SYSTEM DESIGN
3.1 Flow transmitter loops
The BA544D may be connected to almost any
pulse output flowmeter and calibrated to
display rate and total flow in the same or
different engineering units.
Fig 2 illustrates the basic circuit that is used for
all BA544D installations.
Fig 2 BA544D flow application
3.2 Pulse input
As shown in Fig 2, the BA544D will count
pulses from a wide variety of transducers
enabling it to display the output from almost
any flowmeter.
The instrument has one pulse input, but two
sets of input terminals enabling it to
accommodate different types of transducers.
Terminals 3 and 4 are for voltage pulse inputs
and terminals 5 and 6 are for contact and open
collectors inputs.
Note:
Only one pair of input terminals may be
used at a time. i.e pulses can not be counted
from terminals 3 & 4 and from terminals 5 & 6
at the same time.
The following table shows the switching
thresholds for the various transducers, plus the
Summary of Contents for BA544D
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