BEKA BA334NG, Руководство пользователя

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6.23 Reset configuration to factory defaults
r5et def
This function resets the Rate Totaliser including the
lineariser, to the factory default configurations which
are shown in section 6.0
To reset the Rate Totaliser to the factory default
configurations select
r5Et def
from the configuration
menu and press
(
which will result in a
0000
display with the first digit flashing. This is a request
to confirm the reset to factory default instruction by
entering
5urE
. Using the
&
or
*
button set the
flashing digit to
5
and press
(
to transfer control to
the second digit which should be set to
u
. When
5urE
has been entered, pressing the
)
button will
reset the BA334NG to the factory defaults and
return the instrument to the totalising mode.
6.24 Pulse output
The BA334NG Rate Totaliser has an opto-isolated
open collector pulse output with following electrical
parameters:
Ron = 60 Ω + 3V
Roff = 1M
I max = 10mA
The output pulse may be a duplicate of the input
pulse for re-transmission applications, or it may be
derived from the least significant digit of the total
display. When derived from the total display the
output pulse frequency may be divided and the
output pulse width defined.
The retransmitted RTx annunciator on the
instrument display shows the status of the
retransmitted pulse output. Annunciator activation
depends upon the setting of
5ource
in the pulse
output configuration menu.
5caled:
Annunciator activated each time pulse output
open collector is
on , i.e. Ron is less than
60 Ω + 3V.
direct:
Annunciator continuously activated
6.24.1 Ex nA certification
The pulse output is a separate opto-isolated Ex nA
circuit with the following input safety parameters:
Ui = 30V dc
Ii = 100mA
This allows the pulse output to be connected to
any dc circuit providing that in normal operation the
maximum supply voltage is not greater than 30V
dc.
Providing the BA334NG Rate Totaliser is correctly
installed in Zone 2, the pulse output may be
directly connected to any suitably protected
equipment located in Zone 1 or 2 of a hazardous
area, or to equipment located in a safe area. The
pulse output should not be directly connected to
intrinsically safe equipment.
Fig 11 shows a BA334NE Rate Totaliser mounted
in Zone 2 retransmitting a pulse to the safe area.
The current pulse flows through R1 resulting in a
voltage pulse output with an amplitude of about
20V.
To comply with the requirements of
EN 60079-14
Electrical installations design,
selection and erection , each of the wires entering
the hazardous area should be individually fused
and contain a means of isolation. These two
requirements may be satisfied by installing DIN rail
mounted terminals incorporating a fuse which can
easily be removed as shown in Fig 2 to provide
isolation. Clear identification of, and easy access
to the means of isolation is essential for their
effective use. It is also necessary to ensure that
the maintenance procedure makes sure that
unauthorised re-closure of the switches does not
occur. It is not considered necessary to have a
means of isolation or electrical protection for cable
screens.
For some applications Ex nA instrumentation
energised by a current limited power supply or
instrument that can be switched off, is often
considered adequate and to comply with the
requirements of the standard.