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9. ACCESSORIES
9.1 Scale card
The BA358C has a window on the right hand
side of the display to hold a card showing
the units of measurements e.g. Litres,
Gallons, M
3
. Instruments can be supplied
with a printed scale card showing any units
specified at the time of ordering. If a printed
card is not requested, a blank card will be
supplied.
Scale cards can easily be marked on-site as
follows:
a. Remove the rear terminal block(s) and
the rear panel as shown in Fig 8.
b. Carefully pull the rate totaliser
assembly from the enclosure.
c. Gently pull and then slide the blank
scale card towards the display window
until the card is free. Mark the card
with the required legend and replace
in the slot.
d. Reassemble the instrument.
9.2 Tag number
The BA358C can be supplied with a
thermally printed tag number on the rear
panel. This tag number is not visible from
the front of the instrument after installation.
9.3 Alarms
The BA358C 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 output 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 an adjustable setpoint, alarm delay
time, alarm accept time and hysteresis for
rate alarms.
The BA358C total display is up-dated and
compared with the total alarm setpoint once
per second. This may result in the total
alarm being delayed for up to a second after
the total has exceeded the setpoint.
9.3.1 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
less than
5
Ω
+ 0.6V
Roff
greater than 180k
Note: Because of the series protection
diode some test meters may not
detect a closed alarm output.
