BEKA BA364NG, Owner'S Manual

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10.4 4/20mA output
The BA364NG Counter can be supplied with an
optional factory fitted galvanically isolated 4/20mA
output which may be configured to represent the rate
or total display.
10.4.1 Ex nA certification
The optional 4/20mA output is a separate galvanically
isolated Ex nA circuit with the following input
parameters:
Ui = 30V dc
This allows the 4/20mA output to be connected to any
dc circuit providing that in normal operation the
maximum supply voltage is not greater than 30V dc.
Providing that the BA364NG Counter is correctly
installed in Zone 2 the 4/20mA current output may be
used to transmit to suitably protected equipment
located in Zone 1 or 2 of a hazardous area, or to
equipment located in a safe area.
Fig 17 shows a typical application in which a Zone 2
mounted BA337NE Counter is transmitting a 4/20mA
current to the safe area.
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 opened 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.
Fig 17 Application of 4/20mA output
10.4.2 Configuration and calibration
When a BA364NG Counter is supplied with an
optional 4/20mA output the configuration menu is
extended as shown in Fig 18. The 4/20mA output
sub-menu is accessed via the
4-20 oP
function.
The 4/20mA output sub-menu allows the 4/20mA
output to be controlled by the rate or the total
display.
Fig 18 4/20mA output configuration sub-menu
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