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In each I.S. Fieldbus segment only one active source, normally the associated
apparatus, is allowed to provide the necessary power for the Fieldbus system. The
allowed voltage (Uo, Voc, Vt) of the associated apparatus used to supply the bus
must be limited to the range of 14V d.c. to 24V d.c. All other equipment connected
to the bus cable has to be passive, meaning that the apparatus is not allowed to
provide energy to the system, except to a leakage current of 50 µA for each
connected device. Separately powered equipment needs a galvanic isolation to insure
that the intrinsically safe Fieldbus circuit remains passive.
The cable used to interconnect the devices needs to comply with the following
parameters:
Loop resistance R': 15 ...150 Ω/KM
Inductance per unit length L': 0.4...1mH/km
Capacitance per unit length C': 80 ...200 nF/km
C' = C' line/line + 0.5 C' line/screen, if both lines are floating
or
C'= C' line/line + C' line/screen, if the screen is connected to one line
Length of spur Cable: max. 30m
Length of trunk cable: max. 1Km
Length of splice: max. 1m
Terminators
At each end of the trunk cable an approved line terminator with the following
parameters is suitable:
R = 90 ...100 Ω
C = 0 ...2.2 µF.
System evaluation
The number of passive devices like transmitters, actuators, connected to a single bus
segment is not limited due to I.S. reasons. Furthermore, if the above rules are
respected, the inductance and capacitance of the cable need not to be considered
and will not impair the intrinsic safety of the installation.
The sensor circuit is not infallibly galvanic isolated from the Fieldbus input circuit.
However, the galvanic isolation between the circuits is capable of withstanding a test
voltage of 500Vac during 1 minute.
6350QE02revAB.doc 2004-02-06
Rev. AB
Installation Notes For FISCO and Entity Concepts:
1.
The Intrinsic Safety Entity concept allows the interconnection of FM / CSA
Approved Intrinsically safe devices (Div 1 or Zone 0 or Zone1) and
non.incendive apparatus (Div 2 or Zone 2) ,with entity parameters not
specifically examined in combination as a system when: Uo or Voc or Vt ≤
Vmax, Io or Isc or It ≤ Imax, Po ≤ Pi.
Ca or Co ≥ ΣCi + ΣCcable, La or Lo ≥ ΣLi + ΣLcable, Po ≤ Pi.
2.
The Intrinsic Safety FISCO concept allows the interconnection of FM / CSA
Approved Intrinsically safe devices with FISCO parameters not specifically
examined in combination as a system when:
Uo or Voc or Vt ≤ Vmax, Io or Isc or It ≤ Imax, Po ≤ Pi.
3.
Dust-tight conduit seals must be used when installed in Class II and Class III
environments.
4.
Control equipment connected to the Associated Apparatus must not use or
generate more than 250 Vrms or Vdc.
5.
Installation should be in accordance with ANSI/ISA RP12.6 (except chapter 5 for
FISCO Installations) "Installation of Intrinsically Safe Systems for Hazardous
(Classified) Locations" and the National Electrical Code® (ANSI/NFPA 70)
Sections 504 and 505.
6.
The configuration of associated Apparatus must be Factory Mutual Research or
CSA Approved under the associated concept.
7.
Associated Apparatus manufacturer's installation drawing must be followed
when installing this equipment.
8.
The 6350 Series are Approved for Class I, Zone 0, applications. If connecting
AEx[ib] associated Apparatus or AEx ib I.S. Apparatus to the 6350 the I.S.
circuit is only suitable for Class I, Zone 1, or Class I, Zone 2, and is not suitable
for Class I, Zone 0 or Class I, Division 1, Hazardous (Classified) Locations.".
9.
No revision to drawing without prior FM / CSA Approval.
10. Simple Apparatus is defined as a device that neither generates nor stores more
than 1.2V, 0.1A 20uJ or 25mW.
11. The termination must be NRTL approved, and the resistor must be infallible.
12. Warning:
For applications in Div2 or Zone 2 (Classified Locations) Explosion hazard:
Except for field circuits, do not disconnect the apparatus unless the area is
known to be non hazardous.
13 Warning:
Substitution of Components May Impair Safety.
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6350QE02revAB.doc 2004-02-06
Rev. AB
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