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Cabling Solutions for Foundation Fieldbus Systems
By Raman KalraBelden India
Technology Event
Fieldbus Foundation– Changing the Playing Field "
Date : 21st June, 2008 (Saturday)Venue : TROPICANA Conference Room. Hotel : Taj Residency,
Akota Gardens, Vadodara - 390 020 INDIA
Agenda
Foundation Fieldbus Cable Standard
Beyond the Standard- Multi Pair Solutions- Field Barrier and Long Distance Applications
Cost Comparison
Jacket & Armouring Options
FF standard
Colour code orange / blue Jacket colour Orange or Blue (for IS applications)Optional armouring to meet e.g. Atex requirements
IEC 61158/ISA-SP 50 Standards Type AFF SpecificationH1 Cable Test specifications FF844
Conductor Size 18AWG(0.8 sq.mm)Impedance 100ohms +/-20Capacitance Unbalance 4nF/KmConductor DC resistance 24ohms/KmAttenuation@39kHz 3dB/KmMax. Propagation Delay 1.7µS/KmMinimum Shield Coverage 90%Max Network Length 1900m
Key Cable Parameters
Impedance 100 Ω @ 31.25 kHzCapacitance Unbalance < 4 ηF/km (capacitance between one wire and screen to other wire and shield)
Conductor DC Resistance < 24 Ω/kmCable Shielding > 90% coverage
CcS
Ccc
Insulation
Drain wire
Shield Inductance & resistance
Centricity
CcS
Conductor
When twisted pair is exposed to a noise source such as runningmachinery or fluorescent lights, each conductor of the pair isexposed equally.
Capacitance UnbalanceA Twisted Pair Exposed to a Noise Source
Key Cable Parameters
Noise and Signal at the Receiving End of a Typical Pair
Ideal Capacitance Unbalance
When the capacitance of conductors within a pair are not equal, eachconductor will react differently to noise.Total subtraction of noise is virtually impossible.
Key Cable Parameters
When the capacitance of conductors within a pair are different, signals may travel atdifferent rates (velocity).Signal interpretation issues may occur as signals arrive at different times.Lower levels of capacitance unbalance equates to higher noise cancellation.
Key Cable Parameters
FF vs Standard Instrument Cable
FF cable has lower CapacitanceFF cable is designed to a specific impedance to reduce signal reflections and maximize network lengthFF cables are tested during production to meet specific requirements:– Capacitance Unbalance– Impedance– Conductor D.C. resistance
FF Wiring
Control Strategy
Agenda
Foundation Fieldbus Cable StandardBeyond the Standard- Multi Pair Solutions- Field Barrier and Long Distance ApplicationsCost Comparison
Jacket & Armouring Options
Multi Pair Solutions
Multi Pair Fieldbus cables:
2 to 24 pair configurationsEach individual pair meets the FF Type A requirementsOrange or Blue (IS) outer jacketArmouring optionallyOther jacket materials optionally
Agenda
Foundation Fieldbus Cable Standard
Beyond the Standard- Multi Pair Solutions- Field Barrier and Long Distance Applications
Cost Comparison
Jacket & Armouring Options
Fieldbarrier Concept
Fieldbarriers in Zone 1Instrument Spurs in Zone 0Bus trunklinealso used to power the Fieldbarriers
Maximize nr. of instruments on the bus in the zone.
R
PowerPowerSupplySupply
Fieldbus Fieldbus CardCard
Field Field ControlControl StationStation
HumanHuman Interface StationInterface Station
VV--networknetwork
Zone 1Zone 1
Zone 0Zone 0EexEex ia IICia IIC
EExEEx(e)(e) EExEEx(e)(e)
Agenda
Foundation Fieldbus Cable Standard
Beyond the Standard- Multi Pair Solutions- Field Barrier and Long Distance Applications
Cost Comparison
Jacket & Armouring Options
Reduction in hardware costs
4-20 mA
ISISIS ISIS Fieldbus
Less cable
Less installation time
Less I/O Less Interfacing
Reduced footprint in CR
Cost Comparison Vs Instr. Cable
Cost ComparisonWhy is Fieldbus cabling more expensive than standard
instrumentation cable?PP instead of PVC or XLPE on the coresMore insulation material required More complicated process = slower process = higher costs
0
20
40
60
80
100
120
140
160
PLTC ISOS FF Multi Pair BS5308 RE 2X(St)Y
Pric
e In
dex
-
200
400
600
800
1,000
1,200
1,400
Volu
me
in k
m
Agenda
Foundation Fieldbus Cable Standard
Beyond the Standard- Multi Pair Solutions- Field Barrier and Long Distance Applications
Cost Comparison
Jacket & Armouring Options
Jacket options
$$Limited Smoke, Low Acid Gas GenerationHalogen Free
$$$$High & Low Temp, Chemical ExposureTPE
$$$Chemical Wash Downs, Exposure to ChlorinesCPE
$General ApplicationsPVC
CostApplicationsJacket Material
Jacket options
• PVC meeting UL 13 (for physical requirements) (UL 1685 for flame requirements)
• LSNH meeting IEC 60332-3-24 (c)
• CPE (for improved chemical resistance) meeting UL 13 (for physical requirements) (UL 1685 for flame requirements)
• Oil Resistant PVC meeting UL 13(for physical requirements) (UL1685 for flame requirements)
• TPE jacket for improved flexibility meeting UL 13(for physical requirements) (UL 1685 for flame requirements)
Armouring options
Interlock– Aluminum– Steel
Protective Metal Tapes– Smooth or Corrugated (longitudinal or spiral
wrapped)• Copper• Aluminum• Steel
SWA (Steel Wire Armour)– Steel
Why use armour
Physical protectionMaintain signal integrityProvides additional shieldingReduces cost of conduitDirect BurialEasy to install and re-routeRodent ProtectionHazardous Locations – Class 1, DIV. 1 in Canada– Class 1, Div. 2 or Class 2, Div. 2 in USA– Zone 0, 1 or 2 IEC 60079 and Cenelec
FOUNDATION Fieldbus Features
PlantDiagnostics
process orequipment
Level 4
actuators, elementsvalves, connections
Field PerformanceDiagnostics
Level 3
Fisher
DeviceDiagnostics
Level 2
electronics
CommunicationsDiagnostics
Level 1
communicationsFisher
More information from field devices.
•Reduced maintenance –
Diagnostics/Adv diagnostics/ Asset Management
• Pro-active maintenance –
Fact based maintenance, avoid “no action” work
In order to achieve this all passive and active components have to be optimized
for a flawless data-transmission
Questions?