Yamatake HGC303, Руководство пользователя

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Installation Yamatake Corporation
2-12 Model HGC303 - Heat Value Gas Chromatograph
2-4 : Fieldbus installation
2-4-1 : Fieldbus requirements
Fieldbus components and characteristics
Cable
Various types cables are usable for fieldbus.
Type A is the preferred fieldbus cable.
Yamatake recommends type A as the fieldbus cable to use.
The table below describes the type of cable and its maximum length, which is speci-
fied in the IEC 1158-2/ISA S50.02 Physical Layer Standard.
Structure: twisted pair cable with overall shield
Detailed specifications of the Type A cable at 25 ° C are as follows;
a) Characteristic impedance: Z0 at 31.25 kHz = 100 ohm +/- 20%
b) Maximum attenuation at 39 kHz = 3.0 db/m
c) Maximum capacitive unbalance to shield = 2 nF/km
d) Maximum DC resistance (per conductor) = 22 ohm/km
e) Maximum propagation delay change 7.8 kHz to 39 kHz = 1.7 us/km
f) Conductor cross-sectional area (wire size) = 0.8 mm2 (#18 AWG)
g) Minimum shield coverage shall be 90%
Figure 2-7 Example of Type A fieldbus cable structure
Table 2-1: Fieldbus cable description
Type Cable description Size Maximum length
A Shielded, twisted pair
#18 AWG (0.8 mm
2
)
1900m (6232 ft.)
Support
Conductor
Insulator
Taping
Shield foil
Shield wire
Shield net
Jacket