BEKA BA534D, Manual

Page: 18 / 26

18
8. ACCESSORIES
8.1 Units of measurement and instrument
identification
All BA534D 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 when
the instrument is ordered. 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 3. Add the
required legend to the display label, or replace
with a new pre-printed label which is available
from BEKA associates.
The BA534D can also be supplied with a blank or
custom engraved stainless steel plate secured by
two screws to the side of the instrument
enclosure. 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 BA534D 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.
WARNING
These alarm outputs should not be used
for critical safety applications such as a
shut down system.
When the BA534D power supply is turned off or
disconnected, both BA534D alarm outputs will
open irrespective of whether normally open or
normally closed outputs have been selected.
When designing a system an open output should
therefore be the alarm condition.
Alarm annunciators on the instrument display
indicate the status of both alarms. 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 applied to rate
alarms.
The BA534D total display is up-dated and
compared with the programmed alarm setpoint
twice per second, irrespective of the display
update time selected. This may result in the total
alarm being delayed for up to half a second after
the total has exceeded the setpoint.
8.2.1 Solid state output
Each alarm has a galvanically isolated single pole
solid state switch output as shown in Fig 8. The
outputs are polarised and current will only flow in
one direction. Terminals A1 and A3 should be
connected to the positive side of the supply.
Ron = 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
Fig 8 Equivalent circuit of each alarm output
Fig 9 Typical alarm application