4
3.2 Zones, Gas Groups and T rating
The BA304NC has been certified as Group II,
Category 3G apparatus as defined in the ATEC
Directive and as Ex nL IIC T5 Tamb -40 to 60
o
C.
‘L’ indicates that the BA304NC uses an energy-
limiting technique to achieve compliance as
defined in EN 60079-15. This technique is based
on the philosophy of
intrinsic safety
which limits the
current and voltage applied to components which
may generate a spark in normal operation. e.g.
switches and potentiometers
These approvals confirm that the BA304NC is safe
in normal operation and may be:
Installed in a Zone 2 hazardous area
At ambient temperatures between
-40 to 60
o
C.
Used in gase groups:
Group A
propane
Group B
ethylene
Group C
hydrogen
Having a temperature classification of:
T1
450ºC
T2
300ºC
T3
200ºC
T4
135ºC
T5
100ºC
Although certified safe in normal operation at
ambient temperatures between –40 and +60ºC,
the guaranteed operating temperature range of
the BA304NC is –20 to +60ºC.
This allows the BA304NC indicator to be installed
in a Zone 2 low risk hazardous area and to be
used with most common industrial gases.
3.3 Input parameters
Input terminals 1 and 3 may be safely connected in
series with any 4/20mA loop providing that in
normal operation the input current to the indicator
does not exceed 40mA.
3.4 Certification Label Information
The certification information label is fitted on the
top outer surface of the enclosure. It shows the
ATEX certification information plus BEKA
associates name and location.
The instrument serial number and date of
manufacture are shown on a separate label within
the instrument enclosure.
4. SYSTEM DESIGN FOR ZONE 2
4.1 Transmitter loops
A BA304NC indicator may be connected in series
with almost any 4/20mA current loop and
calibrated to display the measured variable or
control signal in engineering units.
Fig 2 illustrates a typical application in which a
BA304NC indicator is connected in series with a 2-
wire transmitter and controller.
Fig 2 BA304NC in a transmitter loop
There are four basic design requirements:
1.
In normal operation the voltage, current
and power applied to the terminals 1 and 3
of the BA304NC must not exceed:
Ui
=
4V
Ii
=
40mA dc
Pi
=
0.2W
Providing the maximum input current in
normal operation is less than 40mA, the
maximum voltage between the indicator
terminals and the maximum input power to
the indicator will be automatically limited to
less than the above figures by the internal
safety components.
