Emerson Rosemount 5900C Reference Manual page 105

Reference Manual
00809-0100-5901
Grounding - F
Signal wiring of the fieldbus segment can not be grounded. Grounding out one of the
signal wires may shut down the entire fieldbus segment.
Shield wire ground
To protect the fieldbus segment from noise, grounding techniques for shield wire usually
require a single grounding point for shield wire to avoid creating a ground loop. The
ground point shall be located at the power supply.
The devices designed for "daisy-chain" connection offer an isolated shield loop-through
terminal in order to enable a continuous shield throughout the Tankbus network.
In order to avoid unintentional grounding points, the cable shield inside the terminal
compartment must be isolated.
3.4.3 Cable selection for the Tankbus
Use shielded twisted pair wiring for the Rosemount 5900C Series in order to comply with
FISCO
fieldbus cable. The cables must be suitable for the supply voltage and approved for use in
hazardous areas, where applicable. In the U.S. explosion-proof conduits may be used in
the vicinity of the vessel.
Use wire rated at least 5 °C above maximum ambient temperature.
We recommend cable size 1.0 mm
cables within the range 0.5 to 1.5 mm
The FISCO F
with the following cable parameters:
Table 3-11: FISCO Cable Parameters
Parameter
Loop resistance
Loop inductance
Capacitance
Maximum length of each spur
Maximum cable length including trunk
spurs
(1) For further information see requirements of the IEC 61158-2 standard
(2) A spur is an unterminated part of the network.
(3) A trunk is the longest cable path between two devices on the fieldbus network, and is the part of
the network which has terminations at both ends. In the Rosemount Tank Gauging system, a
trunk is typically located between the Rosemount 2410 Tank Hub and a segment coupler or the
last device in a daisy-chain configuration.
(4) See IEC 61158-2
Rosemount 5900C Radar Level Gauge
OUNDATION
(4)
requirements and EMC regulations. The preferred cable is referred to as type "A"
™
Fieldbus specification requires that cables for the Tankbus comply
OUNDATION
(1)
(2)
cable
™
Fieldbus
2
or 18 AWG in order to facilitate wiring. However,
2
or 20 to 16 AWG can be used.
Value
15 Ω/km to 150 Ω/km
0.4 mH/km to 1 mH/km
45 nF/km to 200 nF/km
60 m in apparatus class IIC and IIB
(3)
and 1000 m in apparatus class IIC and 1900 m in
apparatus class IIB
Installation
September 2019
105