Engineering
16
207321 / 941160310190
2018-04-16·BA00·III·en·04
Zone 2 Ex i Field Device Coupler 8 Spurs
Series 9411/24
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6.2
Proof of Intrinsic Safety
Proof of intrinsic safety in accordance with FISCO
A spur is intrinsically safe if:
• The field device is certified in accordance with FISCO.
• The conditions for cable values as per IEC/EN 60079-27 are complied with:
R
Cable
: 15 to150 Ω/km
L
Cable
: 0.4 to 1 mH/km
C
Cable
: 45 to 200 nF/km.
Proof of intrinsic safety in accordance with the classical "entity concept"
A spur is intrinsically safe if the safe maximum values of the field device and spur
connections meet the following conditions:
Whereby C
Cable
and L
Cable
describe the total capacity and inductance of the spur cable
respectively, which result from the specified cable length.
6.3
Cable Lengths for Trunk and Spurs
The basis for measuring cable lengths for the trunk and spurs is IEC 61158-2,
Annex B (without taking into account explosion protection).
Note the following points when laying cables:
• The maximum length of all cables (all trunks, all spurs) per segment must not exceed
1900 m.
• The actual trunk and spur lengths can be shorter due to voltage drop.
• The following generally applies: Spurs should be kept as short as possible.
Maximum spur length = 120 m.
6.4
Earthing / Shielding
6.4.1 Connect the Field Device Coupler to an Earth Potential
• Always connect field device couplers to the equipotential bonding! When doing so,
ensure that there is a conductive connection between the earth bolt and the
equipotential bonding.
Observe the installation conditions:
DIN rail / plastic enclosure
• When mounting the field device coupler on a DIN rail and/or installing it in a plastic
enclosure, connect the earth bolt with a connecting line (min. 4 mm
2
) to the
equipotential bonding.
Spur of a field device coupler
Field device
U
0
(
U
i
I
0
(
I
i
P
0
(
P
i
C
0
(
C
i
+ C
Cable
L
0
(
L
i
+ L
Cable
Summary of Contents for 9411/24 Series
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