BEKA BA314E, Manual

Page: 33 / 58

9. ACCESSORIES
9.1
Units of measurement & instrument
identification.
New BA314G Tachometers are supplied with a printed
scale card showing the units of measurement and tag
information specified when the instrument was
ordered. If this information was not supplied a blank
scale card will be fitted which can easily be marked
with a dry transfer or a permanent marker on-site.
Custom printed scale cards are available as
accessories and may be easily fitted as shown in
section 5.4 of this manual.
The BA314G can also be supplied with a blank or
custom laser engraved stainless steel legend plate -
see Fig 7. The plate, which after installation is visible
from the front of the instrument, is supplied loose with
two fixing screws for securing it to the rear of the
instrument's back-box. This plate can typically
accommodate:
1 row of 5 alphanumeric characters 10mm high
or 1 row of 6 alphanumeric characters 7mm high
or 2 rows of 10 alphanumeric characters 5mm high
9.2 Display Backlight
The BA314G Tachometer can be supplied with a
factory fitted backlight that produces green
illumination enhancing display contrast and enabling it
to be read at night or in poor lighting conditions. The
backlight is internally powered from the instrument so
that no additional wiring or intrinsically safe interface
is required, but the instrument supply current
increases to 32mA.
9.3 Alarms
The BA314G Tachometer can be supplied with
factory fitted, dual isolated solid state single pole
alarm outputs that may be independently configured.
Each may be configured as a speed or run-time
alarm with a high or low function having a normally
open or closed output. An alarm delay and alarm
silence time can be included and hysteresis may be
applied to speed alarms.
CAUTION
These alarm outputs should not be used
for critical safety applications such as a
shut down system.
When the BA314G Tachometer power supply is
turned off or disconnected, 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 chosen
for the alarm condition. Alarm annunciators on the
instrument display indicate the status of each alarm.
If an alarm delay or silence time has been selected
the annunciator will flash during the delay or silence
period.
The BA314G internal counters are up-dated and
compared with the alarm setpoint twice per second,
irrespective of the display update time selected.
This may result in an alarm being delayed for up to
half a second after speed or run-time has exceeded
the alarm setpoint.
9.3.1 Solid state output
Each alarm has a galvanically isolated single pole
solid state switch output as shown in Fig 13. 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 = less than 5

+ 0.7V
Roff = greater than 1M

Note: Because of the series protection diode some
test meters may not detect a closed alarm
output
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