BEKA BA364E, Руководство пользователя

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10. ACCESSORIES
10.1 Units of measurement & instrument
identification.
New BA364G Counters 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 BA364G 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
10.2 Backlight
The BA364G Counter 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 power
supply so that no additional wiring or intrinsically safe
interface is required, but the supply current
increases as shown below.
BA364G
Maximum
current
consumption
Without backlight 10mA
Additional for backlight 16mA
Addition with terminals 3 & 4 linked 6mA
Addition with terminals 7 & 8 linked 6mA
----------
Total current 38mA max
10.3 Alarms
The BA364G Counter can be supplied with factory
fitted dual alarms. Each may be independently
configured as a rate display or total display, high or
low alarm. with a normally open, or a normally closed
solid state output.
Configurable functions for each alarm include
adjustable setpoint, alarm delay time and alarm
silence time.
Hysteresis may be applied to rate
alarms.
WARNING
These alarm outputs should not be used
for critical safety applications such as a
shut down system.
When the BA364G 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 BA364G 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 the rate or total has exceeded the
setpoint.
10.3.1 Solid state output
Each alarm has a galvanically isolated single pole
solid state switch output as shown in Fig 14. 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
Fig 14 Equivalent circuit of each alarm output
10.3.2 Intrinsic safety
Each alarm output is a separate galvanically isolated
intrinsically safe circuit with output safety parameters
complying
with the requirements for simple
apparatus . This allows the alarm output terminals
A1 & A2 and A3 & A4 to be connected to almost any
intrinsically safe circuit protected by a Zener barrier
or galvanic isolator providing the output parameters
of the circuit do not exceed:
Uo 28V dc
Io 200mA
Po 0.84W
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