Maximum Overall Cable Length; Maximum Spur Length; Number Of Field Devices; Shielding And Grounding - Endress+Hauser Proline Prosonic Flow 93C Operating Instructions Manual

Wiring
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4.1.2

Maximum overall cable length

The maximum network expansion depends on the type of protection and the cable specifications.
The overall cable length is made up of the length of the main cable and the length of all spurs >1 m
(3.28 ft).
Note the following points:
• The maximum permissible overall cable length depends on the cable type used (→ ä 25).
• If repeaters are used, the maximum permissible cable length is doubled.
A maximum of three repeaters are permitted between user and master.
4.1.3

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
Max. length per spur
4.1.4

Number of field devices

According to IEC 61158-2 (MBP) a maximum of 32 field devices may be connected per fieldbus
segment. However, this number may be restricted in certain circumstances (type of ignition
protection, bus power option, current consumption of field device).
A maximum of four field devices can be connected to a spur.
4.1.5

Shielding and grounding

The optimum electromagnetic compatibility of the fieldbus system is guaranteed only when system
components and in particular lines are shielded and the shielding provides the most complete
coverage possible. Shield coverage of 90% is ideal.
Shielding should be connected as often as possible with the reference ground. The national
regulations and guidelines governing the installation of electrical equipment also apply where
relevant!
Where there are large differences in potential between the individual grounding points, only one
point of the shielding is connected directly with the reference ground. In systems without potential
equalization, cable shielding of fieldbus systems should therefore only be grounded on one side, for
example at the fieldbus supply unit or at safety barriers.
Caution!
If the cable shielding is grounded at more than one point in systems without potential equalization,
network frequency equalization currents can occur that damage the bus cable or the bus shielding
and substantially affect signal transmission.
Proline Prosonic Flow 93C FOUNDATION Fieldbus
1...12 13...14
120 m (393 ft) 90 m (295 ft)
15...18 19...24
60 m (196 ft) 30 m (98 ft)
Endress+Hauser
25...32
1 m (3.28 ft)