NewBase 22 April 2024 Energy News issue - 1718 by Khaled Al Awadi (AutoRe...
Introducing F OUNDATIONTM Fieldbus Technology
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5. What Is Fieldbus? P L F Automation and Display Systems Fieldbus Process Plant Fieldbus - a digital, two-way multi-drop communication link among intelligent measurement and control devices, and automation and display systems.
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8. F OUNDATION Fieldbus Benefits REDUCED WIRING AND INSTALLATION Traditional 4-20 mA wiring, one IS barrier, one pair for each device 4-20 mA IS IS IS IS One IS barrier, one pair for many devices IS Fieldbus
9. F OUNDATION Fieldbus Benefits EXPANDED VIEW OF PROCESS IS IS IS IS 4-20 mA Fieldbus IS
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11. F OUNDATION Fieldbus Benefits DISTRIBUTION OF FUNCTIONS PID PID 4-20 mA PID AO AI In today’s systems, control functions all reside in central controllers. Fieldbus can be used in the same way, but fieldbus also enables control and I/O functions to be distributed to field instruments. AI IS Fieldbus AO
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14. Fieldbus Wiring 24v Nom Fieldbus Power Supply Terminator Terminator Fieldbus Wire Signal Isolation Circuit Fieldbus Devices
17. Shielded Twisted Pair Cable Cable Jacket Shield Drain Wire Two Colors of Power/Signal Wire Shield with 90% Coverage
18. Terminal Blocks To Control Building (Single or Multi-Pair) (Shielded) Inside Junction Box Field Devices Twisted Pair (Shielded) Shields not shown Fieldbus Terminator
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23. Wiring Two Devices on a Segment Power supply not shown = Terminators, in J-Box Spurs with one device are limited to 120 meters each J-Box J-Box Single or multi-pair cable Spur T T T
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26. Wiring Using Tree Topology T T Homerun Cable 120 Meter Spur HMI J-Box This fieldbus includes 4 devices and 3 devices on three spurs, so maximum spur length is 120 meters (next table) Power supply not shown = Terminators T
27. Maximum Spur Lengths Total Devices On Segment 1 Device per Spur 2 Devices per Spur 3 Devices per Spur 4 Devices per Spur 25 - 32 1 m 1 m 1 m 1 m 19 - 24 30 m 1 m 1 m 1 m 15 - 18 60 m 30 m 1 m 1 m 13 - 14 90 m 60 m 30 m 1 m 2 - 12 120 m 90 m 60 m 1 m Recommended Maximum Spur Length
28. Cable Types / Bus Segment Length Cable Type Gauge No. Max. Length A: Twisted-pair with Shield H1 (31.25kbps) #18AWG 1900 m B: Multi-twisted-pair with Shield H1 (31.25kps) #22AWG 1200 m C: Twisted-pair without Shield H1 (31.25kbps) #22AWG 400 m D: Multi-core with Shield H1 (31.25kbps) #16AWG 200 m Any existing, good quality #18 AWG twisted pair cable can be used for fieldbus.
29. Cable Length Calculation Cable Type A B C D H1 Total Length* 1900 m / 6234 ft 1200 m / 3937 ft 400 m / 1312 ft 200 m / 656 ft * Total length including all spurs Terminators and power supplies not shown Field Devices J Box Spur Homerun Cable # of Devices 25 - 32 19 - 24 15 - 18 13 - 14 2 - 12 Total Max Spur Length** 1 m / 3 ft 30 m / 98 ft 60 m / 197 ft 90 m / 295 ft 120 m / 394 ft ** Maximum length of any spur
30. Exceeds Maximum Spur Length T 500 m 500 m Homerun cable T J Box J Box J Box No Good
31. Correct Installation J Box J Box J Box T 500 m 500 m Homerun cable T Fieldbus Repeater T T
32. More Control with Installed Wires J-Box Three existing 4-20 mA Pairs T T Fieldbus devices Three existing pairs, one used for fieldbus J-Box