SMAR FY302, Инструкция по установке, эксплуатации и обслуживанию

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Installation
1.5
Table 1.2 presents in detail the specifications of the several cables at 25 ºC. It is worth to remind
that most of the cable manufacturers recommend the operation temperature between -40 ºC and
+60 ºC. It is necessary to verify the critical points of temperature through where the cabling passes
and if the cable supports it. The type A cable resistance of 22 O/Km is valid at 25 ºC. For example,
the resistance of the type A cable to 50 ºC is 24.58
Ω
/Km. That should be taken into account in hot
countries as Brazil.
Type A Type B Type C Type D
Cable Description
Twisted Pair
with Shield
One or more total
twisted pair with
Shield
Several twisted
pair without Shield
Several non-
twisted pair
without Shield
Nominal Driver Section
Area (of the)
0.8 mm
2
(AWG 18)
0.32 mm
2
(AWG 22)
0.13 mm
2
(AWG 26)
0.25 mm
2
(AWG 16)
(Resistance DC
Maximum) Maximum DC
Loop Resistance ( loop )
44
Ω
/Km 112
Ω
/Km 264
Ω
/Km 40
Ω
/Km
Characteristic impedance
(to) at 31.25 KHz
100
Ω
± 20% 100
Ω
± 30% ** **
Maxim Attenuation to 39
KHz
3 dB/Km 5 dB/Km 8 dB/Km 8 dB/Km
Maximum Unbalanced
Capacitance
2 nF/Km 2 nF/Km ** **
Group Delay Distortion
(7.9 to 39 KHz)
1.7 µsec/Km ** ** **
Surface Covered by the
Shield
90% ** - -
Recommendation for
Network Extension
(including spurs )
1900 m 1200 m 400 m 200 m
Table 1.2 – Characteristics of the Several Cables Used in Foundation Fieldbus H1
Total Cable Length and Distribution and Installation Rules
The total length of the H1 cable should be considered from the exit of the point of PSI ( power supply
impedance – power supply with active impedance) until the most distant point of the segment,
considering the derivations. Remember that spurs smaller than 1 m don't enter in this total.
The cabling total length is the sum of the main bus trunk size plus all the spurs (branches larger than
1 m), and with type A cable, the length is a maximum 1900 m in non-safety areas. In safe areas with
type A cable, it is a maximum 1000 m, considering that the spurs cannot exceed 30 m.
In installation and distributions terms avoid splices, in other words, any part of the network with a
specified conductive medium and a discontinuous length smaller than 1 m, for example: shielding
removal, wire diameter changes, connection to bare terminals, etc. In networks with total length
larger than 400 m, the sum of the lengths of all the splices should not surpass 2% of the total length
and also, in lengths smaller than 400 m, should not exceed 8 m.
A H1 segment maximum length, when using different cable types is limited by the following formula:
1
max max max max
〈=
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
+
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
+
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
+
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
LD
LD
LC
LC
LB
LB
LA
LA
Where:
LA
: Length to the cable
A
;
LB
: Length to the cable
B
;
LC
: Length to the cable ;
C
LD
: Length to the cable ;
D
max LA
: Maximum length allowed with the cable
A
(1900 m);
max LB
: Maximum length allowed with the cable
B
(1200 m);
max LC
: Maximum length allowed with the cable (400 m);
C
max LD
: Maximum length allowed with the cable (200 m).
D