Endress+Hauser RID14, Operating Instructions Manual

Page: 17 / 56

RID14 Wiring
Hauser 17
The electrical data of the fieldbus cable have not been specified but determine important
characteristics of the design of the fieldbus, such as distances bridged, number of users,
electromagnetic compatibility, etc.
Type A Type B
Cable structure Twisted pair of cores, shielded Individual or multiple pairs of
twisted cores, complete shield
Wire cross-section 0.8 mm
2
(18 in
2
) 0.32 mm
2
(22 in
2
)
Loop resistance (direct current) 44 Ω/km 112 Ω/km
Characteristic impedance at 31.25 kHz 100 Ω ±20 % 100 Ω ±30 %
Attenuation constant at 39 kHz 3 dB/km 5 dB/km
Capacitive asymmetry 2 nF/km 2 nF/km
Envelope delay distortion (7.9 to 39 kHz) 1.7 mS/km *)
Shield coverage 90 % *)
Max. cable length (incl. spurs > 1 m 1 900 m (6 233 ft) 1 200 m (3 937 ft)
*) not specified
Suitable fieldbus cables (type A) from various manufacturers for non-hazardous areas are
listed below:
• Siemens: 6XV1 830-5BH10
• Belden: 3076F
• Kerpen: CeL-PE/OSCR/PVC/FRLA FB-02YS(ST)YFL
5.3.2 Maximum overall cable length
The maximum network expansion depends on the type of protection and the cable
specifications. The overall cable length combines the length of the main cable and the
length of all spurs (>1 m/3.28 ft). Please note the following:
• The maximum permissible overall cable length depends on the cable type used.
• If repeaters are used, the maximum cable length is doubled. A maximum of three
repeaters are permitted between the user and master.
5.3.3 Maximum spur length
The line between the distribution box and field device is described as a spur. In the case of
non-Ex applications, the max. length of a spur depends on the number of spurs (> 1 m
(3.28 ft)):
Number of spurs 1 to 12 13 to 14 15 to 18 19 to 24 25 to 32
Max. length per spur 120 m (393 ft) 90 m (295 ft) 60 m (196 ft) 30 m (98 ft) 1 m (3.28 ft)
5.3.4 Number of field devices
In systems that meet FISCO with Ex ia type of protection, the line length is limited to max.
1 000 m (3 280 ft). A maximum of 32 users per segment in non-Ex areas or a maximum of
10 users in an Ex-area (Ex ia IIC) is possible. The actual number of users must be
determined during the planning stage.