4
2.1 Controls
The BA327C and BA328C are controlled and
calibrated via four push-button switches. In the
display mode these switches have the following
functions:
P
While this button is pushed the
indicator will display the input current in
mA, or as a percentage of the
instrument span depending upon how
the indicator has been programmed.
When the button is released the normal
display in engineering units will return.
The function of this push-button is
modified when alarms or a tare function
are fitted to the indicator.
Down
While this button is pushed the
indicator will display the number which
the indicator has been calibrated to
display with a 4mA input. When
released the normal display in
engineering units will return.
Up
While this button is pushed the
indicator will display the number which
the indicator has been calibrated to
display with a 20mA input. When
released the normal display in
engineering units will return.
E
No function in the display mode.
3. INTRINSIC SAFETY CERTIFICATION
3.1 ATEX certificate
The BA327C and BA328C have been issued with
an EC-Type Examination Certificate number
ITS02ATEX2028 by Notified Body ITS Testing and
Certification Ltd. This confirms compliance with
the European ATEX Directive for Group II,
Category 1G equipment, EEx ia IIC T5. The
instruments bear the Community Mark and, subject
to local codes of practice, may be installed in any
of the European Economic Area (EEA) member
countries. ATEX certificates are also acceptable
for installations in Switzerland. This manuals
describes installations which conform with
EN60079:Part 14. When designing systems for
installation outside the UK th local Code of
Practice should be consulted.
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.
Although the BA327C and BA328C 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 BA327C and
BA328C to be connected into any intrinsically safe
circuit protected by a EEx ia IIC certified 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 2 is:
Ci
= 20nF
Li
= 10µH
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 BA327C and BA328C have been certified EEx
ia IIC T5. When connected to a suitable system
the indicator 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.
