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8. ACCESSORIES
8.1 Units of measurement and instrument
identification
All BA554D rate totalisers are fitted with a
display label behind the armoured glass window.
This label can be supplied printed with any units
of measurement and tag information specified at
the time of ordering. Alternatively the
information may be added on-site via an
embossed strip, dry transfer or a permanent
marker.
To gain access to the display label remove the
terminal cover by unscrewing the two 'A' screws
which will reveal two concealed 'D' screws.
Remove all four 'D' screws and carefully lift off
the front of the instrument - see Fig 4. Add the
required legend to the display label, or replace
with a new pre-printed label which is available
from BEKA associates
The BA554D can also be supplied with a blank
or custom engraved stainless steel plate
secured to the instrument terminal cover by
tamperproof screws. This plate can
accommodate:
1 row of 9 alphanumeric characters 10mm high
or 1 row of 11 alphanumeric characters 7mm high
or 2 rows of 18 alphanumeric characters 5mm high
8.2 Alarms
The BA554D can be supplied with two solid
state single pole outputs which may be
independently programmed as high or low, rate
or total alarms with normally open or normally
closed outputs.
Fig 9 illustrates the conditions available for a
rate alarm and shows which are fail safe, i.e.
output is in the alarm condition (open) when the
4/20mA input current is zero. Similarly, when
programmed as a total alarm, the output should
be open in the alarm condition.
WARNING
These alarm outputs should not be
used for critical safety applications
such as a shut down system.
Fig 9 Rate alarm outputs
The status of each alarm is indicated by an
alarm annunciator on the instrument display. If
an alarm delay or silence time has been
selected the annunciator will flash during the
delay or silence period.
Programmable functions for each alarm include
adjustable setpoint, alarm delay time and alarm
accept time. Hysteresis may be added when
programmed as a rate alarm.
The BA554D total display is up-dated and
compared with the programmed alarm setpoint
once per second. This may result in the total
alarm being delayed for up to one second after
the total has exceeded the setpoint.
8.2.1 Solid state output
Each alarm has an isolated single pole solid
state switch output as shown in Fig 10. The
outputs are polarised and current will only flow
in one direction. Terminals 8 and 10 should be
connected to the positive side of the supply.
Vmax
30V dc
Imax
250mA dc
Ron
5
Ω
+ 0.6V
Roff
greater than 180k
