5
subtracted from the maximum cable
capacitance and inductance permitted by the
system certificate of the loop into which the
BA358C is connected.
3.3 Reset terminals
The BA358C total display may be reset to
zero by connecting the reset terminals RS1
and RS2 together. These two terminals
have the following safety parameters:
Uo
5V dc
Io
1.3mA dc
Po
1.6mW
Ui
28V dc
Ii
98mA
Pi
0.65W
The maximum equivalent capacitance and
inductance between them is:
Ci
=
1.2nF
Li
= 0
µ
H
The total display may be reset from within
the hazardous area by any mechanically
operated switch having 500V rms insulation.
This may be connected directly to terminals
RS1 and RS2, no Zener barrier or isolator is
required. Alternatively, the BA358C may
be programmed so that the total display is
reset to zero when the Up and Down push-
buttons are operated simultaneously.
To reset the total display from the safe area
a Zener barrier or intrinsically safe relay is
required to transfer the contact closure into
the hazardous area. Acceptable interface
devices and the maximum permissible cable
parameters are defined by the BA358C
system certificates. Almost any intrinsically
safe relay with certification permitting the
contacts to be connected into the hazardous
area may be used. Alternatively, one of the
positive diode return Zener barriers listed in
the system certificate may be used - see Fig
3A.
3.4 Zones, gas groups and T rating
The BA358C has been certified to show
compliance with the requirements for Group
II Category 1G equipment, EEx ia IIC T5.
When connected to a suitable system the
instrument 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
350
o
C
T5
100
o
C
At an ambient temperature between –40 and
+60
o
C.
Note:
the guaranteed operating temperature
is –20 to +60
o
C
This allows the BA358C 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 rate
totaliser 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.
3.5 Certification Label Information
The certification label is fitted in a recess on
the side of the enclosure. It shows the
ATEX certification information, the date of
manufacture, serial number plus BEKA
associates’ name and address. Non
European certification information may also
be included. The instrument serial number
is also shown on a separate label adjacent
to the field terminals.
