1Fieldbus FoundationTMFacts and Figures

about Cable and Wiring

Raymond NgBelden Singapore Pte Ltd

2Agenda

Foundation Fieldbus Cable Standard IEC 61158-2 FF-844

Cable Selection Standard instrumentation cable vs- FF cable AWG size, Shielding, Jacketing, Armor types

Cable Installation & Termination Q & A

3IEC 61158-2 Type A Cable Specification

Impedance: 100 Ohms Attenuation: < 3 dB/km Capacitance Unbalance:

4nF/km max. Conductor DC

Resistance: 24 Ohms/km max.

Maximum Propagation Delay Change: 1.7 s/km

Wire Size: .8mm sq.(18 AWG) nominally

Shield Coverage > 90%

CcS

Ccc

Insulation

Drain wire

Shield

CcS

Conductor

Jacket

4FF-844 Cable Test Specification

Builds on IEC Requirements to further qualify cables

Addition to IEC requirements Expands on shielding requirements Specifies 10 to 22 pair twists/meter Jacket Resistance Required and optional cable ratings Recommended connector characteristics

Cable registration is in process

Lay Length

5Instrumentation vs- FF Cable

FF Cable Polyolefin Insulation

Electronic grade insulation

100 Ohm Impedance 66% Velocity of

Propagation Designed with tolerances

necessary to meet FF specifications

Instrumentation Cable PVC or XLPE Insulation

35-65 Ohm Impedance 55 to 60% Velocity of

Propagation Designed to meet general

minimum instrumentation cable requirements

6Instrumentation vs- FF Cable

FF cable has lower Capacitance FF cable is designed to a specific impedance to

reduce signal reflections and maximize network length

FF cables are tested during production to meet specific requirements: Capacitance Unbalance Impedance Conductor D.C. resistance

7Cable Selection

First consult with local authority having Jurisdiction to ensure regulatory compliance

Selection Guide Conductor Size Shielding Armor Jackets

8Cable Selection Conductor Size

Most common design is one pair 18 AWG Larger AWG (16, 14) provide:

Improved pull strength Electrical benefits, such as:

GreaterCurrent

Capacity

More FieldInstruments

LessVoltage

Drop

LongerDistance

ReducedResistance

9Cable Selection Shielding

Most common design:foil shield only ~ 35 dB of Shield effectiveness Most effective at high frequencies

(>10 MHz) Drain wire for easy termination

Combination shields Foil in addition to braid Shield effectiveness of ~ 80 dB Effective from 60 Hz to GHz

10

Cable Selection Armoring

Interlock Steel Aluminum

SWA (Steel Wire Armor)

Protective Metal Tapes: Smooth or Corrugated (Steel, Copper, Aluminum)

11

Cable Selection Armoring

Why use Armor? Rodent protection Physical integrity Direct burial Reduces cost of conduit Hazardous Locations

12

Cable Selection Jacketing

PVC most common jacketing material CPE good chemical and abrasion resistance LSZH low smoke zero halogen applications HDPE direct burial applications FEP high or low temperature applications (-70

to 200C)

13

Cable Installation

Follow manufacturers recommendations Bending radii: generally 10 to 12x cable diameter Maximum pulling tension Installation temperature Pulling lubricant selection

14

Cable Termination

Ground shield at one end only The near or host end Use provided drain wire or pigtail the braid Grounding both ends results in ground loops Required to prevent noise ingress, which could distort the signal

Shields should be trimmed back flush with jacket Isolate shield using heat shrink tubing or tape This keeps the shield from being inadvertently shorted to the (+)

or (-) wires or grounding at the device end

15

Post Installation Verification

Follow FF Engineering Guide AG-181 Procedure for installing and commissioning fieldbus

segments Use DMM for Resistance & Capacitance

measurements Use Fieldbus Handheld tester to verify installation and

operation

16

Common Installation Issues

Cable shield shorted to (+) or (-) wires Cable shield grounded at both ends, increasing

noise susceptibility Routing of cables in parallel with AC power lines

Minimum of 6 separation per IEEE 518 Minimize parallel runs Cross power lines perpendicularly, when possible

17

Summary

FF-844 created to clarify cable requirements & register products

FF cable requirements are much more stringent than Instrumentation cabling requirements

Select cable that is compatible with application Consult manufacturer for installation &

termination recommendations Follow AG-181 guidelines for testing FF

segments

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www.fieldbus.org

Slide Number 1AgendaIEC 61158-2 Type A Cable SpecificationFF-844 Cable Test SpecificationInstrumentation vs- FF CableInstrumentation vs- FF Cable Cable SelectionCable Selection Conductor SizeCable Selection Shielding Cable Selection ArmoringCable Selection ArmoringCable Selection JacketingCable InstallationCable TerminationPost Installation VerificationCommon Installation IssuesSummarySlide Number 18