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
are zero, therefore only mechnically activated
switches or intrinsically safe relays may be
connected.
The total maximum permitted cable parameters for
all the cables connected to terminals S1 to S7 in a
IIC hydrogen gas must be less than:
Co
=
0.22µF
Lo
=
0.26mH
Although these parameters are not restrictive, for
reliable operation it is recommended that the
cables between the fieldbus display and the
external switch is less than 5m long.
3.5 Alarm outputs
Each of the six optional alarm outputs is a
separate galvanically isolated, solid state, single
pole switch. The EC-Type Examination Certificate
specifies that under fault conditions the voltage,
current and power at each switch output will not
exceed those specified for
simple apparatus
in
Clause 5.7 of EN 60079-11. This allows each of
the BA484DF-F alarm outputs to be connected to
any intrinsically safe circuit protected by a certified
Zener barrier or galvanic isolator providing that the
output parameters of each circuit are less than:
Uo =
28V dc
Io
=
200mA
Po =
0.84W
The
maximum
equivalent
capacitance
and
inductance of each BA484DF-F alarm output is:
Ci
= 40nF
Li
= 20µH
To determine the maximum permissible cable
parameters, Ci and Li must be subtracted from the
maximum cable capacitance and inductance
specified by the system certificate of the circuit
connected to the switch.
3.6 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, a statement that the
instrument is a FISCO Field Device, plus BEKA
associates name and location. Non-European
certification information may also be included.
The instrument serial number and year of
manufacture are recorded on a separate label
inside the terminal compartment.
4. SYSTEM DESIGN FOR HAZARDOUS
AREAS
4.1 FISCO Systems
The BA484DF-F FOUNDATION™ fieldbus display
may be connected to any FISCO compliant
fieldbus segment providing the segment can
provide the additional 25mA required to operate
the Fieldbus Display.
Fig 2 shows a typical fieldbus segment. To comply
with FISCO requirements, the power supply,
terminators, field devices and the interconnecting
cables must conform with the requirements
specified in IEC 60079-11.
Fig 2 FISCO fieldbus system
4.2 Non-FISCO Systems
If the BA484DF-F Fieldbus Display is to be
connected to a fieldbus segment that does not
comply with FISCO requirements, the safety
parameters of the power supply and the Fieldbus
Display should be compared using the entity
concept.
6
Summary of Contents for FOUNDATION BA484DF-F
Page 9: ...Fig 6 Dimensions and terminal connections 9...
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