IM 01C25T02-01E
2-5
2. HANDLING CAUTIONS
Note 5. Special Conditions for Safe Use
• In the case where the enclosure of the
Pressure Transmitter is made of aluminium,
if it is mounted in an area where the use of
category 1 G apparatus is required, it must
be installed such, that even in the event of
rare incidents, ignition sources due to impact
and friction sparks are excluded.
Note 6. Installation instructions
• From the safety point of view the circuit
shall be considered to be connected to earth.
As this deviates from the FISCO system in
acordance with IEC TS 60079-27 care has to
be taken that the (local) installation require-
ments are taken into account as well.
When used in a potentially explosive
atmosphere, requiring the use of apparatus of
equipment category 1D or 2D, certified
cable entry devices shall be used that are
suitable for the application and correctly
installed.
FISCO Model
Non-Hazardous
Locations
Hazardous Locations
F0201-1.EPS
Ter mi nator
(FISCO Model)
Ex i
Field Instruments
(Passive)
Hand-
held-
Ter minal
Supply Unit and
Safety Barrier
(FISCO Model)
Ter mi nator
Data
U
U
I
I.S. fieldbus system complying with FISCO
The criterion for such interconnection is that the
voltage (Ui), the current (Ii) and the power (Pi), which
intrinsically safe apparatus can receive, must be equal
or greater than the voltage (Uo), the current (Io) and the
power (Po) which can be provided by the associated
apparatus (supply unit).
Po Pi, Uo Ui, Io Ii
In addition, the maximum unprotected residual capaci-
tance (Ci) and inductance (Li) of each apparatus (other
than the terminators) connected to the fieldbus line
must be equal or less than 5 nF and 10 H respec-
tively.
Ci 5 nF, Li 10H
Supply unit
The supply unit must be certified by a Notified body as
FISCO model and following trapezoidal or rectangular
output characteristic is used.
Uo = 14...17.5 V (I.S. maximum value)
Io based on spark test result or other assessment,
No specification of Lo and Co is required on the
certificate or label.
Cable
The cable used to interconnect the devices needs to
comply with the following parameters:
Loop resistance Rc: 15...150 Ω/km
Inductance per unit length Lc: 0.4...1 mH/km
Capacitance per unit length Cc: 80...200 nF/km
Length of spur cable: max. 30 m (IIC and IIB)
Length of trunk cable: max. 1 km (IIC) or 5 km
(IIB)
Terminators
The terminator must be certified by a Notified body as
FISCO model and at each end of the trunk cable an
approved line terminator with the following parameters
is suitable:
R = 90 . . . 102 Ω
C = 0 . . . 2.2 F. (0.8...1.2 F is required in
operation)
The resistor must be infallible according to IEC 60079-
11.
Number of Devices
The number of devices (max. 32) possible on a
fieldbus link depends on factors such as the power
consumption of each device, the type of cable used,
use of repeaters, etc.
Entity Model
Non-Hazardous
Locations
Hazardous Locations
F0202-1.EPS
Ter mi nator
Ex i
Field Instruments
(Passive)
Hand-
held-
Ter minal
Supply Unit and
Safety Barrier
Ter mi nator
Data
U
U
I
I.S. fieldbus system complying with Entity model
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