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9. ACCESSORIES
9.1 Units of measurement and instrument
identification
All BA354ND 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 BA354ND 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
9.2 Alarms
The BA354ND 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 BA354ND 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.
9.2.1 Solid state output
Each alarm has a galvanically 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.
Ron
=
5
Ω
+ 0.6V
Roff
=
greater than 180k
