SAES-Z-020

Previous Issue: 24 October 2009 Next Planned Update: 16 April 2017

Revised paragraphs are indicated in the right margin Page 1 of 21

Primary contact: Salem, Hussain Abdullah on 966-3-8801361

CopyrightSaudi Aramco 2012. All rights reserved.

Engineering Standard SAES-Z-020 16 April 2012 Design and Installation of Fiber Optic Cable Systems for Process Control Networks

Document Responsibility: Process Control Standards Committee

Saudi Aramco DeskTop Standards Table of Contents 1 Scope............................................................ 2

2 Conflicts and Deviations................................ 2

3 References.................................................... 2

4 Terms and Definitions................................... 4

5 Design........................................................... 5

6 Installation................................................... 12

7 Testing and Inspection................................ 16

8 Safety Requirements.................................. 17 Annex A Fiber Optic Link Budget................... 19 Figure 1 Optical Link Budget Figure............... 21

Document Responsibility: Process Control Standards Committee SAES-Z-020

Issue Date: 16 April 2012 Design and Installation of Fiber Optic

Next Planned Update: 16 April 2017 Cable Systems for Process Control Networks

Page 2 of 21

1 Scope

This standard covers minimum mandatory requirements governing the design and

installation of fiber optic cable infrastructure systems inside Saudi Aramco process

plants for process control systems applications only. For telecommunications

applications, refer to the applicable SAES-T series standards. All fiber cable

infrastructure systems inside Saudi Aramco process plants are owned by the plants.

2 Conflicts and Deviations

2.1 Any conflicts between this Standard and other applicable Saudi Aramco

Engineering Standards (SAESs), Materials System Specifications (SAMSSs)

Standard Drawings (SASDs), or industry standards, codes, and forms shall be

resolved in writing by the Company or Buyer Representative through the

Manager, Process & Control Systems Department of Saudi Aramco, Dhahran.

2.2 Direct all requests to deviate from this standard in writing to the Company or

Buyer Representative, who shall follow internal company procedure SAEP-302

and forward such requests to the Manager, Process & Control Systems

Department of Saudi Aramco, Dhahran.

3 References

The selection of material and equipment, and the design, construction, maintenance, and

repair of equipment and facilities covered by this standard shall apply with the latest

edition of the references listed below, unless otherwise noted.

3.1 Saudi Aramco References

Saudi Aramco Engineering Procedure

SAEP-302 Instructions for Obtaining a Waiver of Mandatory

Saudi Aramco Engineering Requirement

Saudi Aramco Engineering Standards

SAES-B-008 Restrictions to Use of Cellars, Pits and Trenches

SAES-B-068 Electrical Area Classifications

SAES-J-902 Electrical Systems for Instrumentation

SAES-L-610 Nonmetallic Piping

SAES-P-104 Wiring Methods and Materials

SAES-Q-001 Criteria for Design and Construction of Concrete

Structures




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SAES-Z-001 Process Control System

Saudi Aramco Materials System Specification

09-SAMSS-097 Ready-Mixed Portland Cement Concrete

Saudi Aramco Standard Drawings

AB-036897 Buried/Underground Cable Route Marker Posts

and Signs

3.1 Industry Codes and Standards

The Instrumentation, Systems, and Automation Society

ANSI/ISA-TR12.21.01 Use of Fiber Optic Systems in Class I Hazardous

(Classified) Locations

National Fire Protection Association

NFPA 115 Standards for Laser Fire Protection 2003 Edition

ANSI/NFPA 70 National Electrical Code (NEC)

International Telecommunications Union Telecommunications Standardization Sector (ITU-T)

G.651 Characteristics of a 50/125 m Multimode

Graded Index Optical Fiber Cable

G.652 Characteristics of a Single-Mode Optical Fiber

Cable

G.653 Characteristics of a Dispersion-Shifted Single-

Mode Optical Fiber Cable

G.655 Characteristics of a Non-zero Dispersion Shifted

Single-Mode Optical Fiber Cable

Electronic Industries Association (EIA)

EIA/TIA-492 Detail Specification for 62.5/125 micron Class Ia

Multimode, Graded-Index Optical Waveguide

Fiber

EIA/TIA-492A Sectional Specification for Class Ia Multimode,

Graded-Index Optical Waveguide Fiber

EIA/RS-455 Standard Test Procedures for Fiber Series Optic

Fiber, Cables, and Addendum

EIA/TIA-568 Optical Fiber Cabling Components




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EIA TIA-568A Commercial Building Telecommunication Wiring

Standard

IEC 60874-14 Sectional Specification for Fiber Optic Connector

Type SCFOC/2.5

IEC 60874-10 Sectional Specification for Fiber Optic Connector

Type BFOC/2.5

Building Industry Consulting Service International (BICSI)

TDMM Telecommunications Distribution Methods

Manual

COOP Customer-Owned Outside Plant Design Manual

4 Terms and Definitions

Attenuation: A measure of the decrease in energy transmission (loss of light)

expressed in decibel (dB). In optical fibers, attenuation is primarily due to absorption

and scattering losses.

Coating: A layer of composite plastic material covering the fiber to provide

mechanical protection.

Core: The glass central region in an optical fiber that provides the means for

transmitting light.

Fiber Optic Cable: A cable that contains individual glass fibers, designed for the

transmission of digital information, using light pulses.

Fiber Node: is a location that contains the passive and/or active fiber optic components

to interconnect the fiber feeder with the distribution point.

Fiber Hub: a location with a single feeder cable from a fiber node and multiple fiber

cables to outlying buildings. Fiber hubs are typically used if individual cables from the

node to the buildings are either cost prohibitive or impractical.

Hazardous (classified) location: a location in which fire or explosion hazards may

exist due to an explosive atmosphere of flammable gases or vapors, flammable liquids,

combustible dusts, or easily ignitable fibers.

Multimode: A fiber that allows more than one optical mode to propagate.

Minimum Bend Radius: The minimum radius a fiber may be bent before optical

losses are induced.




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Operating Wavelength: The light wavelength at which a system is specified, normally

expressed in nanometers (nm). Most single mode fibers can operate at 850 nm, 1300 nm

or 1550 nm.

Optical Link Loss Budget: Total losses allowed for satisfactory operation of an

optical fiber system.

Optical Time Domain Reflectometer (OTDR): A device used for characterizing a

fiber, wherein an optical pulse is transmitted through the fiber and the resulting

backscatter and reflections are measured as a function of time.

Process Control Network (PCN): A proprietary process control networks provided as

part of a vendor's standard process control system.

Splicing: A permanent junction between optical fibers may be thermally fused or

mechanically applied.

Splice Loss: The amount of loss of light energy caused by angular misalignment,

and/or fiber end separation, and/or lateral displacement of fiber axes.

Single Mode: A fiber that supports the propagation of only one mode.

5 Design

5.1 System Layout

a) Layout of a fiber optic cable system shall comply with SAES-Z-001.

b) All fiber nodes within the plant shall provide five nines (99.999%)

availability.

c) Composite cable of power and fiber optic shall not be used unless

approved in writing by the Process & Control Systems Department of

Saudi Aramco.

d) Aerial fiber optic cables shall not be used, unless approved in writing by

the Process & Control Systems Department of Saudi Aramco.

5.2 Cable Routing

a) Multiple fiber optic cables between two locations shall be diversely routed

to provide additional reliability and survivability.

b) There shall not be more than one fiber hub between a destination location

and its originating node.

c) Multimode fiber cable runs shall not exceed 2 kilometers between the node

and the final termination point.




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5.3 Cable Sizing

a) Fiber cables shall be sized with at least 50% additional strands above the

initial strand requirements. The following minimum strand count shall

also be applied:

i) 24 strand count for cable run to a building or a facility that is not a

node or hub.

ii) 12 strand count for cable run to small or temporary locations.

b) Fiber strand count in all fiber cable shall be an even number.

c) Spare fiber strands shall be spliced and terminated at the Fiber Distribution

Panel (FDP), and marked as spares.

5.4 Design Documentation

As a part of each telecommunications work order/project, detailed drawings and

documents shall be prepared for each fiber optic cable system, showing the

following information:

5.4.1 Fiber Cable Data

a) Cable manufacturer.

b) Vendor number.

c) Cable size (number of fibers).

d) Cable type (filled or air core).

e) Cable make-up (dielectric or non-dielectric).

f) Type of fiber (multimode or single-mode).

g) Dispersion shifted or non-dispersion shifted.

h) Fiber packaging (e.g., single fiber/loose buffer; multiple fiber/loose

buffer; tight buffer, channel/groove or ribbon type, and color code,

etc.).

5.4.2 Design Drawing

a) Cable route drawing (single line drawings)

b) Cable schematic and detail drawings

c) Wiring closet floor plans

d) Equipment rack layout with distribution panels




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5.4.3 Other information

1. Cable schematic and detail drawings shall identify support

transitions, cable installation method on each section, building

entrances and congested areas.

2. Wiring closet floor plans and equipment rack layout shall identify

cable routing inside the wiring closet and location of fiber

distribution panels.

3. At the completion of the project, cable route drawings, wiring

closet floor plans, and equipment rack layouts shall be revised to

reflect the as built conditions.

4. Origin (normally node or hub) and destination of the cable.

5. Fiber cable splice points with station location.

6. Record the footage and/or meter markings on the engineering

design construction drawings.

7. Change in cable route.

8. All substructures (pipes, utilities, etc.) with station location.

9. Location of marker posts and signs.

10. Cable Identification.

11. Type of splice closures.

5.4.4 Link Loss Budget Requirements

During the design stage a link loss budget shall be prepared and included

with the project proposal and design packages. The link loss budget

shall include:

1. Total fiber attenuation (loss).

2. Splice loss (including pigtail splices, if pigtails are used).

3. Connector loss.

4. A margin for light source aging as per manufacturer's specification.

5. Link loss margin of 3 dB minimum for restoration splices.

Commentary Note:

See Annex A Fiber Optic Link Budget for detail calculation method.

The calculated dB loss cannot exceed the operating range of the terminal

equipment that will be installed. Measured end-to-end loss should




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measure less than the calculated loss. Fibers that measure a higher loss

than the link loss budget will not be accepted.

5.5 Optical Fiber

All plant fiber optic cables for instrumentations and process control networks

installations (intra or inter-building) shall be either;

50 m (core)/125 m (cladding), MULTIMODE, GRADED-INDEX OPTICAL WAVEGUIDE FIBER (In accordance with the latest version of

ITU-T G.651)

Or

62.5 m (core)/125 m (cladding), MULTIMODE, GRADED-INDEX OPTICAL WAVEGUIDE FIBER (In accordance with the latest version of

EIA/TIA-568 series)

Or

m (core)/125 m (cladding), STEP INDEX SINGLE-MODE OPTICAL FIBER (Dispersion-Shifted or Non-Zero Dispersion-Shifted) (In accordance

with the latest version of applicable ITU-T-652, 653, 655)

Commentary Notes:

Selection of the specific fiber type shall depend on applications, speed, distance and future growth requirements.

When MultiMode fiber is selected, 50 m fiber shall be preferred over 62.5 m fiber, since 50 m offers better performance like lower signal attenuation.

All optical fibers shall be coated with one or more plastic materials or

compositions to preserve the intrinsic strength of the glass. The COATING

DIAMETER shall be at least 250.0 15.0 micrometers.

The optical fibers shall consist of a solid glass cylindrical core and cladding

covered by Ultra Violet (UV) acryl ate or equivalent coating.

5.6 Optical Characteristics

a) The maximum attenuation of each fiber within a cable, when normalized

to a length of 1 km shall be as per Table 1.




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Table 1 Optical Signal Attenuation

Fiber Type Wavelength () Max Attenuation

(dB/km)

Multi-Mode

50/125 m

850 nm 4.0

1300 nm 2.0

Multi-Mode

62.5/125 m

850 nm 3.5

1300 nm 1.5

Single Mode

1310 nm 0.5

1550 nm 0.4

b) Measurement of the attenuation shall be conducted at the wavelength

specified for application and must be expressed in dB/km.

c) The Numerical Aperture of Multimode fiber shall be 0.275 0.015

d) The minimum Bandwidth of the Multimode fiber cable shall be 160 MHz-

km @ 850 nanometers and 500 MHz-km @ 1300 nanometers

e) The Numerical Aperture of single mode fiber shall be at least 0.13

5.7 Cable Characteristics

A. Outdoor Cables

1. All 'Outdoor Fiber Optic Cable' shall be loose-tube buffered.

2. Cable shall be constructed of all dielectric materials. There shall be no

metallic materials in the cable including the central strength member.

3. Cable shall contain water-blocking material within the buffer tubes

and the outside cable sheath.

4. Cable shall contain 'Kevlar' threads to provide strain relief and

protection of the buffer tubes.

5. Cable construction shall be such that specified optical transmission

properties are maintained when cable is installed and operated under

manufacturer's specifications for loading, bend radius, and

temperature.

6. For an individual link, same type of cable shall be used to ensure

same performance characteristics and to ensure compatibility of the

geometrical parameters, attenuation and dispersion of the fiber.




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7. Cable with 36 or fewer strands shall have six (6) fibers per buffer

tube.

8. Cable with 37 or more strands may have twelve (12) fibers per

buffer-tube.

9. All fiber optic outdoor cables shall be designed for a minimum

temperature range of -5C to 70C at operating, placement, and

storage conditions.

B. Indoor Cables

1. Indoor cable shall be listed as being suitable for the intended purpose

according to NEC classifications in article 770.

2. Fan-out cables are acceptable for indoor use. Fan-out type must have

each fiber strand contained in its own subunit with a dielectric

strength member around the fiber.

3. Each subunit shall have a jacket with a minimum outside diameter of

2.4 mm.

C. Fiber and Buffer Tube Identification

The colors designated for identification of loose buffer tubes and

individual fibers in multifiber tubes, slots or bundles shall be in accordance

with BICSI COOP design manual. See the following table for details:

Buffer Tube & Fiber No. Color

1 Blue

2 Orange

3 Green

4 Brown

5 Slate

6 White

7 Red

8 Black

9 Yellow

10 Violet

11 Rose

12 Aqua

13 Blue/Black Tracer




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Buffer Tube & Fiber No. Color

14 Orange/Black Tracer

15 Green/Black Tracer

16 Brown/Black Tracer

17 Slate/Black Tracer

18 White/Black Tracer

19 Red/Black Tracer

20 Black/Yellow Tracer

21 Yellow/Black Tracer

22 Violet/Black Tracer

23 Rose/Black Tracer

24 Aqua/Black Tracer

D. Fiber Jumpers

1. Fiber jumpers for multi-mode fiber shall be orange and fiber jumpers

for singlemode fiber shall be yellow.

2. Fiber jumpers for routing inside cabinets shall be factory-built with

each strand within its own subunit cable. Dual or Zipcord fiber

jumpers are acceptable.

3. Jumper cables shall be listed as being suitable for the intended

purpose according to NEC classifications in article 770-50.

E. Fiber Distribution Patch Panel (FDP)

1. Fiber Distribution Panels (FDPs) shall be designed so that the fiber

optic cable enters from the rear of the FDP.

2. FDPs shall be equipped with a mechanism to relieve strain on the

cable.

3. FDPs shall be designed so that, under normal installation, fibers are

not subjected to bends radii less than the minimum recommended by

the manufacturer.

4. FDPs shall be designed to provide access only to individual pairs of

fibers during installation of fiber jumpers or maintenance.

5. FDPs shall have a means of protecting the individual fibers. Under

normal access, the FDP shall not allow contact with the fiber cable or

individual fibers terminated in the FDP.




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6. FDPs shall be designed with storage for excess slack of fiber jumpers

in order to prevent multiple jumpers from becoming tangled with

each other and exceeding their minimum bends radii.

7. FDPs shall have an isolated partition to store splice trays and/or

function breakout transition points.

8. FDPs shall have a protective cover over its front. Cover shall be able

to be modified so that a locking device can be added in the future.

9. Fiber jumpers shall be accessible only from the front of the FDP.

F. Optical Connectors

1. All fiber optic connectors shall comply with EIA/TIA-568. Only the

ST and SC type connectors (as specified in IEC 60874-14 and IEC

60874-10 respectively) shall be used for terminate optical fiber cable.

2. Each plant shall standardize on either ST or SC connectors.

The preferred choice is the SC type.

Commentary Note:

For methods and guidelines on the proper installation and connection of optical fiber cabling, refer to EIA TIA-568A.

6 Installation

6.1 General

1. Direct burial of fiber optic cables is prohibited.

2. Conduit and/or Cable Tray systems shall be used for outdoor and/or indoor

fiber optic cable installation. For details see Sections 6.1, and 6.2;

respectively.

3. Data links fiber optic cables, shall be specified and installed per system

manufacturers' recommendations.

4. When redundant data links are provided, the primary cable shall follow a

different route from the back up cable.

5. Fiber optic cable installation may use existing cable pathway (cable tray,

and conduit system) provided that the existing pathway comply with this

standard.

6.2 Conduit Systems

1. Conduits shall be single bore, plastic (PVC) NEMA TC 8, Type DB or EB.

Same type of conduits should be placed on any specific conduit section.




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2. Conduits used in areas exposed to sunlight shall have built-in protection

from Ultraviolet (UV) light or be treated as outlined in SAES-L-610.

3. Conduits and associated junction boxes shall be permanently marked Fiber

Optic Cable. Label should be in English and Arabic.

4. The total number of conduits shall be designed to accommodate immediate

and foreseeable future growth requirements. In all cases, at least one

additional spare conduit shall be planned for maintenance and repair

purposes. For conduits with sub-ducts (inner duct), an unused sub-duct

may be used as a spare.

5. The length of the conduit runs between two access points is limited mainly

by the size of the cable which will be pulled into it and the number of

bends it will contain. A maximum of equivalent two 90 bends are

permitted in each section of the conduit runs. The minimum bend radius

of the conduits shall be 36.

6. For larger conduits designed for multiple fiber optic cables, sub-duct shall

be used to assist in the future installation of additional fiber optic cables.

Only longitudinally ribbed sub-duct shall be used in conduit runs over

150 meters (500 ft.) long.

7. All underground conduit systems in plant areas shall be concrete encased

for mechanical protection with non-structural concrete as per SAES-Q-001

and 09-SAMSS-097. The minimum amount of concrete shall be 75 mm

along the top, sides and bottom of the conduit formation.

a) Underground conduit systems shall have Electronic Markers placed

directly on top of the concrete.

b) Electronic Markers shall be placed along the route of the conduit

system at a maximum distance interval of 30 meters (100 ft.).

c) Electronic Markers shall be placed at every change in direction, at

the crossing of other utilities or lines, and at below-grade access

points.

d) Marker posts and signs shall be placed in accordance with Standard

Drawing AB-036897, Buried/Underground Cable route Marker posts and Signs.

e) In plant areas, where vehicular traffic loads is expected, conduits

should be located at least 760 mm (30) below surface grade. Plant areas, where vehicular traffic load is unlikely, conduits should be

located at least 610 mm (24) below surface grade.

f) A yellow color marker tape shall be placed above the conduit concrete encasement to provide early warning. The marker tape shall




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be located at a minimum of 300 mm above the upper surface of the

conduit system.

g) In plant area, underground manholes, hand holes, re-enterable

splices, and access or service points are not allowed. All service and

access points shall be above ground.

8. Installation of Fiber Optic System in Class I locations shall comply with

NEC Article 501.

6.3 Cable Tray Systems

1. Cable tray design, specification and installation shall be in accordance with

SAES-J-902; Electrical Systems for Instrumentation; Section-9.

2. Fiber Optic cables shall not be installed in cable trays sharing with high

voltage transmission or distribution cables. High voltage cable is defined

as cables that carry circuits operating at over 480 volts.

6.4 Transitions

1. Fiber Optic cables shall be adequately supported (i.e., conduit or cable

tray) at transitions from one type of installation method to another and also

at transitions from one cable tray to another.

2. Cables shall be adequately supported at transitions into equipment,

cabinets and patch panels.

3. Water seals must be used to prevent moisture entering in conduits where

ever the conduits and sub ducts are exposed.

6.5 Cable Installations

1. Fiber Optic cable installed for control networks shall not be used for any

other applications or services, SAES-J-902 Section 13.

2. Do not install any other type of (copper or other metallic) cable other than

non-metallic fiber optic cables in the same conduit.

3. Because of the possibility of damaging existing cables, as well as the other

uncertainties involved, pulling new cables through a partially filled conduit

is generally not recommended.

6.6 Cable Bending

Bending radius of fiber optic cable shall not be less than:

1. Ten (10) times the cable diameter when the cable is not under tension

2. Twenty (20) times cable diameter when the cable is under tension




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6.7 Cable Splicing

To keep future 'opening' of the new cable to a minimum, underground fiber

optic cable splices shall be located at points where future branch splices will be

required, in so far as it is practical to do so.

6.8 Cable Fill in conduits/sub-ducts

The cross-sectional area of the cable should not exceed:

1. 28% of the inside cross-sectional area of the conduit sections or sub-ducts

with two 90 bends;

2. 34% of the inside cross-sectional area of the conduit sections or sub-ducts

with one 90 bend; and

3. 40% of the inside cross-sectional area of the straight runs (no bends)

conduit sections or sub-ducts.

6.9 Cable Pulling

Only cable manufacturers' recommended pulling tension, pulling methods and

pulling equipment shall be used. Fiber Optic cables should always be pulled in

a straight line. The cable shall never be bent or wrapped around hand or any

other objects for pulling. In the absence of manufacturer's recommendation, the

cable pulling tension shall not exceed 600 pounds.

6.10 Cable Protection

During cable short and long term storage and cable handling, the cable shall be

protected against environmental hazardous material and conditions that may be

detrimental to the cable; like petroleum, petroleum based products, thermal,

other chemical, mechanical, electrical conditions, etc.

6.11 Cable Entrances

Fiber Optic Cables entering in buildings, control rooms or other indoor facilities

shall comply with BICSI - TDMM (Building Industry Communications Services

International - Telecommunications Distribution Methods Manual, Section-9).

In addition, cable entry into control buildings or similar buildings in

hydrocarbon processing plants shall also comply with SAES-P-104; Wiring

Methods and Materials, Section 15.4.

The following guidelines shall be observed:

1. Do not use power cable runways (AC and/or DC) to support optical cables.




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2. Install a new runway or conduit to support the planned optical fiber cable

if the facility:

i. Is equipped with a cable grid only, and/or

ii. Does not have available existing cable troughs or race ways.

3. Optical fiber cables may be routed with other high frequency (CXR) cable.

4. Avoid a route that would stack future cables in excess of 225 kg/m on top

of fiber cables.

5. Do not exceed the fiber cable's minimum bending radius.

6. Coil 10 meters of slack cable for restoration.

6.12 Fire Protection requirement

1. All Fiber optic cables placed inside buildings, control rooms, offices, shall

comply with the fire protection requirements in accordance with

ANSI/NFPA 70, NEC Article 770.

2. Outdoor fiber optic cables (non-fire rated) shall not be run exposed for

more than 15.2 m (50.0 ft) within a building. If more than 15.2 m (50.0 ft)

of cable is required between the building entrance point and the cable

termination point, use rigid metallic conduit to enclose the cable to bring

the exposed part of the cable to within 15.2 m (50.0 ft) or less of the

termination. The metallic conduit must be grounded.

3. Wrapping the outdoor cable with fire-rated tape as an alternative is not

acceptable.

4. Conduit and cable sealing, wherever are required, shall be installed in

accordance with NEC Article 505.16.

7 Testing and Inspection

7.1 End-to-end testing shall be carried out on all outside plant fiber optic cable

facilities (defined as the span of fiber from the transmitter to the receiver) and

the overall optical loss shall be documented.

7.2 Acceptance Testing Requirements

The following acceptance testing shall be conducted for all fiber optic cables:

A. End-to-end acceptance tests (typically conducted after completion of

installation and splicing and before installing terminal equipment).




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B. Splice acceptance tests (individual splice insertion losses) shall be .05 dB

average link splice loss with no single splice loss above 0.1 dB for fusion

splices, and 0.1 dB average link splice loss with no single splice loss above

.2 dB for mechanical splices; connectors shall have insertion losses of

0.3 dB or less).

Commentary:

Not required for patch cable.

C. On-reel acceptance tests shall be performed on the cable to confirm the

manufacturer's tests before the placing operation begins.

D. Each link shall be tested for zero transmission error performance at the

highest bit rate expected to be carried over the cable section. This test is to

be performed with a transmission analyzer.

8 Safety Requirements

Classified Area considerations

1. Fusion splicing shall not be used in classified areas

Commentary Notes:

Note 1: Fusion splicing process uses an electric arc to make optical splices which could cause fires and/or explosions.

Note 2: All fusion splices shall be made outside the classified areas and at least 3 meters away.

2. The Use of Fiber Optic Systems in Class I Hazardous (Classified) Locations shall

comply with ISA-TR12.21.01-2004.

3. Fiber Optic cables that are routed on trays in classified areas shall be specified per

ISA-TR12.21.01-2004 and shall be marked on the outer jacket as suitable for tray

application.

4. Fiber optic cable used in hazardous (classified) locations must meet the fire

resistance and smoke producing requirements of NEC Section 770.53.

5. Fiber optic cable used in Class I locations must be sealed in accordance with the

requirements specified in NEC Section 501.15 or 505.16, as appropriate.

6. SAES-B-068 shall be used for electrical classification of plant areas where

flammable gases or vapors, or combustible dust may be present in the air in

quantities sufficient to produce ignitable mixture.




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7. SAES-B-008 governs restrictions for on-site below-grade trenches and other

appurtenances where hazardous vapors may collect.

Revision Summary

16 April 2012 Revised the Next Planned Update. Reaffirmed the content of the document, and reissued with minor revision.




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Annex A

Fiber Optic Link Budget

This annex is included for information purposes

The following is a step by step methodology for designing the power loss budget of a fiber

optic link (Figure 1):

1. Calculate Transmitted Power:

Generally, the transmitter power that is quoted by the manufacturer is the power

into the fiber. If not, then the coupling loss must be determined.

Power into fiber (dBm) = TX power (dBm) - coupling loss (dBm)

2. Calculate the System Gain

Subtract the receiver sensitivity from the transmitted power. Both values must be

in the same type of units (most common unit is dBm) and must be of the same

measurement type (average power or peak power). The system gain will then be

represented in decibels.

System gain (dB) = TX power (dBm) - RX sens. (dBm)

3. Determine the safety margin

Calculate the safety margin for the fiber link. The safety margin is represented in

decibels.

Safety margin (dB) = Environmental factor (dB) + Aging factor (dB) +

Dispersion factor (dB) + Jitter factor (dB) + Repair factor (dB) + Design

error margin (dB)

Commentary Note:

The recommended safety margin is 4 dB.

4. Calculate the link loss budget

Determine the maximum allowable loss for the end-to-end optic fiber cable link

section by subtracting the safety margin from the system gain.

Link loss budget (dB) = System gain (dB) - Safety margin (dB)




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5. Calculate the total connector losses

Calculate the total connector losses in a link section of optic fiber by multiplying

the number of connectors in that section by the loss per connector (in dB).

Total Connector Losses (dB) = Connector Loss (dB) x number of

connectors

6. Calculate the total splice losses

Calculate the total splice losses in a link section of optic fiber by multiplying the

number of splices by the loss per splice (in dB).

Total Splice Losses (dB) = splice loss (dB) x number of splices

7. Calculate other possible losses

Calculate other losses to the system by adding together losses due to passive

components in the optic fiber route. For example: passive stars, combiners,

splitters, etc.

8. Calculate the maximum allowable cable attenuation

Each section of fiber link should be analyzed to determine the maximum

allowable fiber optic cable attenuation. This is calculated by subtracting the

connector losses, splice losses and other losses from the link loss budget.

Allowable cable attenuation (dB) = Link loss budget (dB) -

Connector losses (dB) - Splice losses (dB) - other losses (dB)

9. Calculate the fiber loss for each cable section

Calculate the expected signal attenuation from each section of optic fiber by

multiplying the cable length for a section by the specified normalized cable

attenuation of the chosen cable.

Fiber loss (dB) = fiber length (km) x normal cable attenuation (dB/km)

10. Calculate System Fade Margin

Fade Margin= Link Loss Budget (dB) - fiber loss (dB) - connector losses

(dB) - splice losses (dB) - other losses (dB)

Commentary Note:

Fade Margin shall be greater than zero. The recommended fade margin gain is 3dB.




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11. Calculate the received signal level

Determine the power level of the signal at the end of the fiber that is entering the

receiver. This is calculated by subtracting all the losses along the cable section

from the transmit power into the fiber.

Received signal level (dBm) = transmit power (dBm) - fiber loss (dB) -

connector losses (dB) - splice losses (dB) - other losses (dB)

12. Check dynamic range

Ensure that the receive signal level at the end of the fiber section does not exceed

the maximum permitted signal level allowed into the receiver. This is calculated

by adding the dynamic range to the receiver sensitivity and ensuring that the

receive signal level is less than this result.

Receive signal level (dBm) < Receiver sensitivity (dBm) + Dynamic range

(dB)

Commentary Note:

Optical link budget calculation software tool the will calculate the entire link loss budget, is available in P&CSD website.

Figure 1 Optical Link Budget Figure

SAES-Z-020

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