4
3.2 4/20mA input
In Europe, sources of energy which do not
generate more than 1.5V; 100mA or 25mW are, for
intrinsic safety purposes, considered to be
simple
apparatus
(Clause 5.7 of EN 60079-11).
Although the BA307C and BA308C indicators do
not themselves comply with the requirements for
simple
apparatus
, the EC-Type Examination
Certificate specifies that under fault conditions the
voltage, current and power at the 4/20mA input
terminals 1 & 3 will not exceed those specified for
simple apparatus
. This allows the BA307C and
BA308C to be connected into any intrinsically safe
circuit protected by a Zener barrier or galvanic
isolator providing the output parameters of the
circuit do not exceed:
Uo
=
30V dc
Io
=
200mA
Po
=
0.85W
The EC-Type Examination Certificate specifies that
the maximum equivalent capacitance and
inductance between the two 4/20mA input
terminals 1 and 3 is:
Ci
=
20nF
Li
=
10
H
To determine the maximum permitted cable
parameters, these figures should be subtracted
from the maximum cable capacitance and
inductance permitted by the certificate for the loop
into which the indicator is installed.
3.3 Zones, gas groups and T rating
The BA307C and BA308C have been certified as
Group II, Category 1G, EEx ia IIC T5 apparatus at
Tamb –40 to 60
o
C. When connected to a suitable
system the instruments may be installed in:
Zone 0 explosive gas air mixture
continuously present.
Zone 1 explosive gas air mixture likely to
occur in normal
operation.
Zone 2 explosive gas air mixture not
likely to occur, and if it does
will only exist for a short time.
Be used with gases in groups:
Group A propane
Group B ethylene
Group C hydrogen
Having a temperature classification of:
T1
450
o
C
T2
300
o
C
T3
200
o
C
T4
135
o
C
T5
100
o
C
At ambient temperatures between –40 & +60
o
C.
Note: Operation only specified between –20
o
C and
+ 60
o
C.
This allows both indicators to be installed in all
Zones and to be used with most common Industrial
gases.
WARNING installation in Zone 0
When installed in a Zone 0 potentially
explosive atmosphere requiring apparatus
of Category 1G, the indicator shall be
installed such that even in the event of rare
incidents, an ignition source due to impact
or friction between the aluminium enclosure
at the rear of the instrument mounting panel
and iron/steel is excluded.
3.4 Certification label information
The certification label is fitted in a recess on the
top outer surface of the enclosure. It shows the
ATEX certification information, instrument serial
number, year of manufacture plus BEKA
associates’ name and location. Non European
certification information may also be included.
BA307C certification label
