Fieldbus Foundation TM Physical Design. Joseph Khoo AP Regional Sales Director R.Stahl

Transcription

1 Fieldbus Foundation M Physical Design Joseph Khoo AP Regional Sales Director R.Stahl 1

2 Fieldbus How is fieldbus different to 4-20mA? Wiring and Interconnection Components opologies Design tools Installation principle Earthing/Grounding principle 2

3 How is Fieldbus Different from 4-20mA? 4-20mA fieldbus P.S. P.S. Parallel connection Cable carries digital data from/to all the devices on the bus Plenty of information Data integrity checks 3

4 How does it work? ma mA Isolator 4 time 4-20mA 4-20mA 4

5 How does it work? ma Speed: approx. 2 values per second Loop time: 500ms bps (bit per second) 4-20mA + HAR Isolator 4 time 4-20mA 4-20mA + HAR 5

6 How does it work? Speed: approx. 25 values per second Loop time for 3 devices: 120ms (e.g.) ma bps (bit per second) Device 1 Device 2 Device 3 ypically 20mA per device base current Constant current + Fieldbus Fieldbus Power Supply (FPS) time Fieldbus 6

7 Physical layer elements Gen. Purpose Host Computer 24VDC FFPS Power supply / Conditioner FF Power Supply & Conditioner &erminator Wiring Block & erminator Wiring components H1 Interface (non-is) runk (non-is) Spurs Cable Device 1 Device 2 Device 3 his concept is typically applied to: Any kind of instrument in the safe (non hazardous) area Ex na instruments in Zone 2 Ex d instruments in Zone 1 7

8 Physical Layer IEC Physical Layer standard 31.25kbit/s transmission rate Up to 32 devices per segment - depends on several factors Limited to 16 by host (in the market) Limited to less by distance Limited to less by process cycle time Shielded twisted pair recommended can use existing field wiring 2-core-cable carries power and signal (like HAR) Up to 1900m (total) with best cable up to 9.5km with repeaters Up to 120m spur length

9 Physical Layer Point-to-point ( = 1 device only) - not cost efficient Line (bus with spurs) - high maintenance Daisy chain - prone to failures Chickenfoot (tree) - Highest reliability, best practice Can be intrinsically safe Line Daisy chain Chickenfoot Device connection 9

10 Fieldbus Cable Instrumentation Cables Electrical power cable with poor noise immunity Fieldbus Foundation Cable ype and Description ype A: Multi or single-twisted-pair, individually shielded ype B: Multi-twisted-pair, with an overall shield ype C: Multi-twisted-pair, without a shield ype D: Multi-core, without twisted pairs with an overall shield Max Length 1900 m (6232 ft.) 1200 m (3936 ft.) 400 m (1312 ft.) 200 m (656 ft.) 10

11 Fieldbus Cable Example: ype A cable: Shielded twisted pair Recommended ype A does not specify the diameter; You can get type A cable in AWG 22, AWG 18, AWG 16, etc ype A is also available as multicore: as long as individual pairs are twisted and shielded, it is type A

12 Permitted Spur Lengths Control Room Equipment runk Spurs Devices per Spur otal Device 1 Device 2 Devices 3 Devices m 90 m 60 m m 60 m 30 m Device 1 Device 3 Device 2 Not recommended m 30 m 1 m he spur length is reduced by 30 meters for each additional device on a spur. 12

13 Physical layer elements Gen. Purpose Host Computer 24VDC FFPS Power supply / Conditioner FF Power Supply & Conditioner &erminator Wiring Block & erminator Wiring components H1 Interface (non-is) runk (non-is) Spurs Cable Device 1 Device 2 Device 3 13

14 Single Power Supply Conditioner (Examples) FISCO, FNICO Redundant, Multi-segment 14

15 Wiring blocks Please not this way 15

16 Wiring Blocks (Examples) Fieldbus Barriers Ex me [ia] Zone 1/0 Ex ia Zone 2 Ex nl Zone 1 Ex me 16

17 erminators Required for all balanced transmission lines (= differential signal not referenced to ground, 0V, earth or so) Eliminates reflection (matches cable impedance) Converts +/- 9mA comms current signal into voltage signal here should be exactly two terminators per bus segment: one at each end Each terminator has 100 Ohms (for AC signal), they are in parallel: resulting resistance is 50 Ohms +/- 9mA into 50 Ohm 900mVpp signal amplitude If one terminator is missing: +/- 9mA into 100 Ohm 1800mVpp signal amplitude If 3 terminators connected: +/- 9mA into 33 Ohm 600mVpp signal amplitude Integrated into FF power supplies and wiring blocks 17

18 opology Gen. Purpose Host Computer 24VDC FFPS Power supply / Conditioner FF Power Supply & Conditioner &erminator Wiring Block & erminator Wiring components H1 Interface (non-is) runk (non-is) Spurs Cable Device 1 Device 2 Device 3 his concept is typically applied to: Any kind of instrument in the safe (non hazardous) area Ex na instruments in Zone 2 Ex d instruments in Zone 1 18

19 opology Gen. Purpose IEC Physical Layer standard 31.25kbit/s transmission rate Up to 32 devices per segment - depends on several factors Limited to 16 by host Limited to less by distance Limited to less by process cycle time Shielded twisted pair - can use existing field wiring Cable carries power and signal Up to 1900 meters with best cable up to 9.5km with repeaters Up to 120m spur length

20 opology High Energy runk Host Computer 24VDC FFPS Power supply / Conditioner FF Power Supply & Conditioner &erminator Fieldbus barrier & erminator Fieldbus Fieldbus barrier barrier H1 Interface Ex e (non-is) runk Intrinsically Safe Spurs Cable Device 1 Device 2 Device 3 his concept is typically applied to: Ex nl instruments in Zone 2 Ex i instruments in Zone 1 or 0 Hazardous area installation 20

21 opology High Energy runk Advantages of High Energy runk concept: Redundant FF power supply can be used Up to 16 instruments (limited by host) Longer cable distances compared to FISCO Spurs connect to FISCO or Entity instruments; simple verification of intrinsic safety 21

22 opology FISCO Host Computer 24VDC FFPS FISCO Power supply Intrinsic safe FF Power Supply & Conditioner &erminator IS Wiring Block & erminator Wiring components H1 Interface Intrinsically Safe runk Intrinsically Safe Spurs Device 1 Device 2 Device 3 his concept is applied to: Ex i/fisco instruments in Zone 1 or 0 Hazardous area installation 22

23 opology FISCO Advantages of FISCO: runk and Spurs are intrinsically safe (1000m, 60m) High reliability (design same as conventional isolator) Up to 16 instruments (limited by host & IIC IIB ) Economically efficient Standardized Ex parameters no verification of intrinsic safety required Verification of intrinsic safety documented by FISCO/FNICO (IEC ) Highest safety (all Ex i) - no mix of protection methods 23

24 opology FISCO ic (formerly FNICO) Host Computer 24VDC FFPS FISCO ic (FNICO) Power supply Safe energy limited FF Power Supply & Conditioner &erminator Ex nl Wiring Block & erminator Wiring components H1 Interface Safe (Ex nl) runk Safe (Ex nl) Spurs Device 1 Device 2 Device 3 his concept is applied to: Ex nl/fisco/fnico instruments in Zone 2 Hazardous area installation 24

25 opology FISCO ic/fnico Advantages of FISCO/FNICO: Same design rules as FISCO Standardized by the same standard (IEC ) Higher power in Zone 2 FISCO devices can be used Most economically efficient High safety - no mix of protection methods 25

26 Fieldbus Design ools (Examples) 26

27 Installation Guidelines Cable ests Experience has shown that new cable irregularities are so infrequent that it is more efficient to check cable after installation Cable Installation Verify that cable is properly installed, bypassing impact from wiring components Segment Checkout Check of proper wiring of wiring components Device installation Check of proper device installation Loop checkout Functional test 27

28 Measurement setup Cable Installation 28

29 Measurement setup Cable Installation Segment Checkout 29

30 Measurement setup Cable Installation Segment Checkout Device installation 30

31 Measurement setup Cable Installation Segment Checkout Device installation Loop checkout 31

32 Good Wiring Practices est segment wiring before connecting components Avoid damaging the wire when removing insulation Ground the cable shield only at one point (at the control room end) Insulate the ungrounded end of the cable shield (at the instrument) Use crimp ferrules Ferrule diameter must fit wire Crimp tool must fit ferrule Ferrule must fit terminals Maintain polarity and associated color codes throughout the segment 32

33 Good Wiring Practices Choose right size Lessons learned: orque screwdriver Wire end ferrules Right (!) wire strippers Fieldbus tester Harms wire strands 33

34 Installation tools Portable fieldbus diagnostic test equipment Measures relevant fieldbus parameters Establish baseline after commissioning 34

35 ypical measured parameters Shield short Easy to measure and understand Further measurements can identify location Signal level Minimum level is specified by Fieldbus specification Low or high levels on all devices suggests incorrect bus termination If only one device, suggests problem on single spur DC voltage Indicates correct function of power supply/conditioner Instrument supposed to operate from 9V onwards Noise Maximum level is specified by Fieldbus specification ri-band measurement helps identify source Retransmissions Good measurement of physical layer health Re-tries can obscure faulty device or network 35

36 Portable diagnostic tools 24VDC Host Computer FFPS FF Power Supply & Conditioner &erminator Wiring Block & erminator H1 Interface PDI Portable Diagnostic Instrument Device 1 Device 2 Device 3 (non-is) Spurs Connect at respective location to obtain accurate measurement. 36

37 Portable diagnostic tools 24VDC Host Computer FFPS FF Power Supply & Conditioner &erminator Fieldbus barrier & erminator Fieldbus Fieldbus barrier barrier H1 Interface PDI Intrinsically Safe Spurs Portable Diagnostic Instrument Device 1 Device 2 Device 3 o measure at fieldbus barrier, PDI needs to be Ex i approved. Important since the galvanic isolation of fieldbus barrier impacts on measurement. 37

38 Earthing/Grounding Grounding in the control room One point grounding only Continuous shield from control room to the field Shield not connected at the field instrument 38

39 Earthing/Grounding 24VDC Host Computer FFPS FF Power Supply & Conditioner &erminator Wiring Block & erminator H1 Interface Device 1 Device 2 Device 3 39

40 Earthing/Grounding 24VDC Host Computer FFPS FF Power Supply & Conditioner &erminator Fieldbus barrier & erminator Fieldbus Fieldbus barrier barrier H1 Interface Intrinsically Safe Spurs Device 1 Device 2 Device 3 40

41 Project Procedure Best practice: Bench test Functional tests and interoperability test FA SA 41

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