5
3. INTRINSIC SAFETY CERTIFICATION
3.1 ATEX certificate
The BA488CF has been issued with EC-Type
Examination Certificate by Notified Body Intertek
Testing Services (ITS) confirming compliance with
the European ATEX Directive 94/9/EC for Group
II, Category 1, gas atmospheres, EEx ia IIC T4.
The instrument bears 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
manual describes installations which conform with
BS EN60079:Part14:1997 Electrical Installation in
Hazardous Areas. When designing systems for
installation outside the UK, the local Code of
Practice should be consulted.
3.2 Zones, gas groups and T rating
The BA488CF has been issued with EC Type
Examination certificate ITS04ATEX22779
confirming that it complies with the requirements
for Group II Category 1 G EEx ia IIC T4 (Tamb –
40 to 60
o
C) specified in the ATEX Directive.
When connected to a suitable system the
BA488CF 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
450oC
T2
300oC
T3
200oC
T4
135oC
At an ambient temperature between –40 and
+60
o
C.
Note
: the guaranteed operating temperature
range of the Fieldbus Display is –20 to +60
o
C
This allows the BA488CF to be installed in all
Zones and to be used with most common
industrial gases.
3.3 Fieldbus connection
The BA488CF Fieldbus Display is powered and
communicates via the fieldbus, which is
connected to terminals 1 and 2. These terminals
comply with the Fieldbus Intrinsically Safe
Concept (FISCO) defined in IEC 60079 Part 27
which simplifies intrinsic safety system design.
The BA488CF may also be connected to non
FISCO compliant fieldbus segments by using the
entity concept to assess safety.
Terminals 1 and 2 of the BA488CF Fieldbus
Display are not polarised and have the following
safety parameters:
Ui
=
17.5V dc
Ii
=
380mA dc
Pi
=
5.32W
For non FISCO compliant segments, the safety
parameters of the power supply or isolator
powering the fieldbus segment must be equal to
or less than these figures.
The maximum equivalent capacitance and
inductance at terminals 1 & 2 of the BA488CF
Fieldbus Display are:
Ci
= 1nF
Li
= 8µH
To determine cable parameters for non FISCO
compliant segments, the sum of Ci and Li of all
the field devices should be subtracted from the
maximum cable parameters permitted by the
device powering the fieldbus segment.
3.4
External switches
For applications requiring operator inputs to be
made by large industrial push buttons, terminals
S1 to S7 facilitate external switches to be
connected to the Fieldbus Display. When
external switches are connected, the BA488CF
may be configured so that the front panel push
buttons continue to function or are disabled.
Terminals S1 to S7 have the following combined
output safety parameters:
Uo
=
14.7V dc
Io
=
146.7mA dc
Po
=
0.58W
The switches and associated wiring connected to
the terminals must comply with the requirements
for
simple apparatus
. i.e. the switch must be
mechanically activated and have IP20 protection,
and both the switch and the wiring must be
capable of withstanding a 500V rms insulation test
to earth for one minute. Most industrial push
buttons and wiring satisfy these requirements.
The input safety parameters of terminals S1 to S7
