Technical_Handbook - OMAN CABLES.pdf - Free Download PDF Ebook

(´.´.Ω.¢T) á«fÉª©dG äÓHÉµdG áYÉæ°U ácô°T IÒ°ùe ‘ ¬à≤≤M ÉÃ á«æW h ¬cô°ûc IQƒîa á«fÉª©dG äÓHÉµdG áYÉæ°U ácô°T ∞≤J äRÉa √ójóY õFGƒéH êƒJ õ«ªàdG ƒëf ÜhDhódG »©°ùdG h ìÉéædG ¿G . øeõdG øe øjó≤Y ¿É£∏°ùdG ádÓ÷G ÖMÉ°U IõFÉéH RƒØdGÉ¡ªgG øe ¿Éc h á∏jƒ£dG É¡JÒ°ùe ‘ ácô°ûdG É¡H .ôjó°üà∏d ΩÉ©dG IõFÉL h ,á«dÉààe äGƒæ°S ¢ùªÿ áYÉæ°üdG π°†aC’ ¬∏dG ¬¶ØM ¢SƒHÉb ⁄ Q’hO ¿ƒ«∏e 0^2 ™«Hh 1984 ΩÉY ‘ ÚØXƒe Iô°û©H á©°VGƒàŸG ácô°ûdG ájGóH ¿G ÚæWGƒŸG øe % 52 º¡æe ∞Xƒe 600 `H Ωƒ«dG h á«ŸÉ©∏d √Gó©J πH á«∏ﬁ ô°üëàj .»µjôeCG Q’hO ¿ƒ«∏e 800 äÉ©«ÑŸG ºéM ≠∏H Ú«fÉª©dG AÉëfCG ™«ª÷ á«ŸÉ©dG IOƒ÷G äGP É¡JÉéàæe á«fÉª©dG äÓHÉµdG áYÉæ°U ácô°T Qó°üJ ¿Gó∏ÑdGh §°Sh’G ¥ô°ûdGh É«°SBGh ≈°übC’G ¥ô°ûdGh IóëàŸG áµ∏ªŸG ‹G ¢üN’ÉHh ⁄É©dG .ÇOÉ¡dG §«ÙG ≈∏Y á∏£ŸG Oman Cables Industry (SAOG) In a journey spanning over two decades, Oman Cables Industry (SAOG) has always strived towards excellence and quality in all its activities. The various awards won by OCI bear testimony to this, be it being the five-time winner of His Majesty’s trophies for the best industry or the various Flame of Excellence and Exporter of the Year awards. OCI exports its products across the globe to Europe, UK, Far East, Asia, Middle East and the Pacific Rim. Having started with just 10 employees and sales of 0.2 million USD in 1984, today OCI is proud of the fact that it employs 52% Omani nationals amongst its 600 employees, and has a sales turnover of 800 million USD. 1 OCI/PBTB/Rev-001/010909 OCI/PBTB/Rev-001/010909 . . . . .20 Short Circuit Current ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . No. . . . . . . . . . . . .9 Electric Field in MV cables . . . . . . . . . . .41 Cables Storage and Installation Practices . . . . . . . . . .15 General characteristics of Sheathing Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46 Insulation Resistance Test and significance . . . . . . . . . .64 3 OCI/PBTB/Rev-001/010909 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Criteria for selection of Cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Details Page Product Range . . . . . . . . . . . . . . . . . .Table of Contents Sr. . . . . . . . . . . . . . . . . . . . . . . . . . . . .57 Overhead Conductor – Characteristics and Applications . . . . . . . . . . . . . . . . . . . .43 Testing of Cables . .7 Conductor details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56 PVC vs XLPE cables – Comparison .61 Frequently Asked Questions . . . . . . . . . . . . . . . . .62 Conversion Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 General characteristics of Insulating Materials . . . . . . . . . . . . . . . . . . . . .50 Voltage drop – utility and values . . . . . . . . . . . . . . . . . . . . . . . . . .16 Continuous Current Ratings and rating factors . . . . .53 Earthing and Bonding methods . . . . . . . . . . . . . . . . . BS 6724 and specific customer requirements with: a) b) c) d) e) f) Copper and Stranded Aluminium Conductors Single core and multicore cables Unarmoured cables Aluminium wire armoured single core cables Galvanized Steel Wire and Galvanized Steel Tape armoured multicore cables. PVC Sheathed Wires to BS 6004. with and without screen (copper tape/copper wire). The products listed below are the most popular ones.OCI Product Range Oman Cables offers a wide range of cables for demands made upon electrical. BS 6346. PVC and LSF Sheathed Cables to IEC 605021. XLPE and PVC insulated. IEC 60227 0. 3 Core Flat Wires with and without earth continuity conductor to BS 6004 PVC Insulated Flexible Cords to IEC 60227 300/500 Volts Flexible Cables BS 6500.5 mm2 to 630 mm2 Single core PVC and LSF insulated wires 450/750 Volts to BS 6004. BS 5467. 4 OCI/PBTB/Rev-001/010909 .6/1 kv. BS 7211. mechanical and thermal qualities. Control cables with and without armour. OCI can meet a customer’s special requirements. PVC Insulated. However. 1) Electric Wires: a) b) Building wires from 1. IEC 60227 d) e) f) 2) 2 Core. IEC 60227 c) Multicore 300/500 Volts Circular. BS 7889. c) d) e) f) g) All Aluminium Alloy conductors (AAAC) Aluminium Conductors Steel Reinforced (ACSR) Aluminium Conductors Aluminium Clad Steel Reinforced (ACSR/AW). Medium Voltage XLPE insulated cables to IEC 60502-2. BS. FRRT. Galvanized Steel Wire and Galvanized Steel Tape armoured multicore cables. We can offer cables with Optional Features such as: Watertight Conductors Bonded or Strippable Insulation Screen Copper Wire/Copper Tape Screen Cables with longitudinal water barriers at screen and armour level.3. Cables with LLDPE. AAC/PVC. VDE. BS 7835. 4) Overhead Conductors to IEC. ASTM. Cables with Radial water barrier (PE Laminated Aluminium Tape). MDPE. BS 7870 and specific customer requirements up to and including 46 kV: Copper and Aluminium Conductors: a) b) c) d) e) Single core cables 25 mm2 to 1000 mm2 Three core cables 25 mm2 to 500 mm2 Single core and Three core un-armoured cables with copper tape/copper wire screen. Aluminium Conductors Aluminium Alloy Reinforced (ACAR). AAC/XLPE). Aluminium Alloy Conductor Steel Reinforced (AACSR). 5 OCI/PBTB/Rev-001/010909 . AS Standards a) b) Bare and PVC/XLPE Insulated Hard Drawn Copper Conductors Bare and PVC/XLPE insulated all Aluminium conductors (AAC. DIN. Aluminium wire armoured single core cables. BS 6622. HDPE. FRLS Outer Sheath. FRLS Outer Sheath. HDPE. FRRT. Galvanized Steel and Alumoweld Earth Wires. FRRT. 6) PVC Compounds for Insulation and Sheathing of Electric Cables.T11. T13. e) Instrumentation Cables. 6 OCI/PBTB/Rev-001/010909 . Type 6. Type 9. Aerial Bundle Cables (Duplex. Cable with Oil Resistant and/or Termite Resistant and/or FRRT and/or FRLS Outer Sheath. FR. IEC 60332-3-22. FRLS. Cables with LLDPE. Triplex.h) i) 5. IEC 60332-3-23. Quadruplex). Type ST2. To name a few: Type A. MDPE. ATR etc. Special Cables a) b) c) d) Watertight Cables Fire Retardant Cables to IEC 60332-3-24. For higher fault rating and higher tensile strength steel wires are used in multicore cables. Factors such as Ground & Air temperature. affect specified current ratings. Polyethylene or PVC is material most often used. a) Conductor material – Copper is the virtually unchallenged material as a conductor. Frequency 4) Installation methods and conditions 5) Short time duty and system protection 6) Acceptable Voltage drop 7) Economics How do these factors influence the choice of cables? 1) Application of the cable determines the basic factors for choice of cable type. 4) Chemical substances in the environment might need special requirements on outer covering. Please refer to the chart for properties of sheathing material. Please refer to the chart for major characteristics of different materials. Stainless steel is difficult to justify on cost grounds and Aluminium is the normal choice. depth of laying. 2) 3) System voltage determines Voltage class of cables. Current rating and intermittent load is the decisive factor for fixing conductor size. Earthed or Unearthed System 3) Load Current. Cables are vulnerable to termite and rodent attacks. Single core in AC circuits.Criteria for selection of Power Cables Cable Type and Size should be selected keeping in the view the following: 1) Application 2) Working Voltage. use non magnetic material. can also be used as Conductor material as it is very economical. b) Insulating Material – good insulating material should have low thermal resistivity and low dielectric losses. Duty Cycle. thermal resistivity of soil. d) External covering/sheaths are used over the armour. Aluminium. 7 OCI/PBTB/Rev-001/010909 . c) Power cables are usually with armour to carry earth fault current and to give mechanical protection against damage during installation and service. number of cables in circuit etc. In case expert guidance is desired. 8 OCI/PBTB/Rev-001/010909 . 7) The design of the cable for a particular application must be optimised taking into account all the above factors. please contact OCI. 6) Voltage drop is also major factor in deciding the conductor size of the cable. Voltage drop of the cable for a given route length should not exceed the statutory requirements.5) The short circuit current and its duration determines the size of conductor and thermal requirement of insulation. 16 – – – – – – – – – – – – – – – – – 3.868(a 0.124(b (b (b (b 0.387 0. Started Conductor .08(a 1.5 4 6 10 16 25 35 50 70 95 120 150 185 240 300 2 3 4 Maximum resistance of conductor at 20˚C Circular.0620 9 OCI/PBTB/Rev-001/010909 .268(b (b (b 0.206(d 0.5 2.used in flexible cables and cords.193 (b (b 36.727(b 0.56 4.used in cables for fixed installations.5 18.7 24.0 1.641 0.1 7.75 1.91(a 1.2 7.125(d 0.used in flexible cables and cords. Conductors are more flexible than Class 5 when more flexibility is required Table – Class 1 solid conductors for single core and multicore cables 1 Nominal cross sectional area m2 0.153 0.443 0.11 1. Flexible Conductor .8 18.2 12.101 0.320(d 0. annealed copper Aluminium and aluminium conductors alloy conductors.20(a 0.83 1.used in cables for fixed installations. circular Plain Metal-Coated or shaped /km /km /km Ω Ω Ω 36.Class of Conductors: Class 1: Class 2: Class 5: Class 6: Solid Conductor .41 4.70 3.0775 0.100(d 0.84 1.61 3. Flexible conductor .08 1.1 12.0 24.15 0.164(d 0.5 0.253(d 0.524 0. .0469 0. The maximum resistance to the assembled conductor should be 25% of that of the individual component conductors. For solid aluminium alloy conductors having the same nominal cross-sectional area as an aluminium conductor. circular Plain Metal-Coated or shape /km /km /km Ω Ω Ω 0. For single core cables. four sectoral shaped conductors may be assembled into a single circular conductor. mineral insulated.0291 0. the resistance value should be multiplied by 1. and not for general purpose. annealed copper Aluminium and aluminium conductors alloy conductors. d) 10 OCI/PBTB/Rev-001/010909 .0465(b – – – – – – – – – – – 0.0367 0.0605 0.0778 0.g.0247 Aluminium conductors 10 mm2 to 35 mm2 circular only.162 unless otherwise agreed between manufacturer and purchaser.Table – Class 1 solid conductors for single core and multicore cables 1 Nominal cross sectional area m2 400 500 630 800 1000 1200 a) b) c) 2 3 4 Maximum resistance of conductor at 20˚C Circular. Solid copper conductors having nominal cross-sectional areas of 25mm2 and above are used for particular types of cable e. 11 1.0366 0.0224 0.641 0.20 0.08 1.0176 0.0291 0.0762 0.868 0.0072 36.124 0.0283 0.75 1.0367 0.0754 0.193 0.83 1.0 24.0072 – – – – – – – 3.7 24.0186 0.0090 0.524 0.100 0.0151 0.154 0.16 0.0605 0. 11 OCI/PBTB/Rev-001/010909 .0127 These sizes are non-preferred.15 0. Other non-preferred sizes are recognized for some specialized applications but are not within the scope of this standard The minimum number of wires for these sizes is not specified.268 0.84 1.41 4.0101 0.100 0.0475 0.2 7.0469 0.5 0.0991 0.0221 0.0113 0. 5 or 6 equal segments (Milliken) For stranded aluminium alloy conductors having the same nominal cross-sectional area as an aluminium conductor the resistance value should be agreed between the manufacturer and the purchaser.0607 0.61 3.727 0.0177 0.0470 0.206 0.0165 0.56 4.0149 0. These sizes may be constructed from 4.91 1.734 0.0778 0.0369 0.1 7.164 0.5 2.126 0.253 0.0129 0.0101 0.195 0.320 0.443 0.270 0.1 12.0 1.0090 0.0129 0.0286 0.08 1.70 3.153 0.387 0.0113 0.529 0.0151 0.2 12.8 18.0247 0.391 0.125 0.5 18.Class 2 stranded conductors for single-core and multi-core cables 1 Nominal crosssection al area 2 3 4 5 Minimum number of wires in the conductor Circular Circular Compacted Shaped Cu mm2 0.5 4 6 10 16 25 35 50 70 95 120 150 185 240 300 400 500 630 800 1000 1200 1400 a 1600 1800 a 2000 2500 a) b) c) 6 7 8 9 10 Maximum resistance of conductor at 20˚C Annealed copper conductor Plain wires Aluminium or aluminium alloy conductors Metal-coated Plain wires wires Al Cu Al Cu Al Ω/km Ω/km Ω/km 7 7 7 7 7 7 7 7 7 7 7 19 19 19 37 37 37 37 61 61 61 91 91 91 – – – – – – – 7 7 7 7 19 19 19 37 37 37 37 61 61 61 91 91 91 – – – 6 6 6 6 6 6 6 6 6 12 15 18 18 30 34 34 53 53 53 53 53 b) b) b) b) b) b) 6 6 6 6 6 12 15 15 15 30 30 30 53 53 53 53 53 – – – – – – – – – 6 6 6 12 15 18 18 30 34 34 53 53 53 – – – 6 6 6 12 15 15 15 30 30 30 53 53 53 – – – 36.0212 0.0601 0. 210 0.41 2 Maximum diameter of wires in conductor (mm) Class 5 Class 6 3 4 Maximum resistance of conductor at 20˚C Plain wires Metal-coated wires /km /km Ω Ω 39.21 0.31 0.277 0.95 3.16 0.780 0.393 0.41 0.5 4 6 10 16 25 35 50 70 95 120 150 185 240 300 400 500 630 0.51 0.51 0.1 26.31 0.98 4.26 0.09 3.108 0.16 0.161 0.0495 0.3 7.51 0.0817 0.795 0.21 0.0654 0.31 0.0641 0.21 0.5 2.41 0.41 0.51 0.7 8.5 13.0384 0.95 1.0486 0.206 0.31 0.41 0.21 5.51 0.21 0.41 0.7 20.16 0.39 1.Class 5 flexible copper conductors for single core and multi-core cables 1 Nominal crosssectional area mm2 0.0801 0.91 1.0 19.21 0.0292 12 OCI/PBTB/Rev-001/010909 .41 0.106 0.132 0.51 0.21 0.24 0.0 1.21 0.51 0.16 0.164 0.272 0.61 0.386 0.565 0.26 0.129 0.41 0.554 0.0287 40.21 0.31 0.16 0.30 1.51 0.0391 0.75 1.16 0.31 0.61 0.31 0.5 0.0 13.21 0.0 26. the electric field of the conductor attains radial symmetry and is confined to Insulation for safety consideration. 2. To prevent surface discharges and reduce electrical interferences Please see the difference between shape of Electric field of shielded (screened) cable and unshielded cable Non-Shielded Shielded 13 OCI/PBTB/Rev-001/010909 . Insulation Screening 1. Intimate contact between Insulation and semiconducting layer prevents partial discharge. the electric field is the highest at conductor surface. To distribute electrical stress uniformly along the periphery of the cable 3. To provide uniform stress over the relatively rough stranded conductor surface. With the outer shield grounded. Field distribution within a high voltage XLPE cable Purpose of Semiconducting screens for such cables – Conductor Screening:1. 4.Electric Field in Medium Voltage XLPE Cables As shown in the figure below. reducing towards the outer surface of the insulation. 2. To provide close bonding between the conductor and adjacent insulation so as to exclude any interspersed voids that may constitute sources of partial discharge. Minimum installation temperature Dimensional stability under heat Maximum operating temperature 14 OCI/PBTB/Rev-001/010909 PVC Good Excellent Good Good Good – Good – Good – – Good – Poor – Good – – – Fair – – – Excellent – – – Good – – Poor – – Poor – – – Poor Polyethylene Excellent Excellent Excellent Excellent Fair – Poor – Exceptional – Excellent (Slight swelling above 60˚C) Good – Excellent (Slight swelling at higher temperatures) – – Good – – – Excellent – – – Excellent – – Good – – Good – – – Poor Yes 23-30% 26 14˚F (-10˚C) Fair 80˚C No 17-18% 0 -40˚F (-40˚C) Fair 80˚C .Outer Covering materials selection chart Mechanical Abrasion Resistance Tensile Strength Elongation Compression Resistance Flexibility Environmental Flame Moisture Fresh or salt water Petroleum oils Motor oil Fuel oil Crude oil Creosote Paraffinic Hydrocarbons Gasoline Kerosene Alcohols Isopropyl Wood Grain Mineral Acids Sulfuric Acid Nitric Acid Hydrochloric Acid Fixed Alkalis Sodium hydroxide (lye) Potassium hydroxide (potash) Calcium hydroxide (lime) Ketones Acetone Methyl ethyl ketone (MEK) Esters Ethyl Acetate Most lacquer thinners Halogenated Hydrocarbons Chloroform Carbon Tetrachloride Methyl Chloride General Leaves protective residue after combustion Oxygen Index (ASTM D-2863) Halogen content – % Wt. 037 (70˚C) 3.75 kV) 10 125 Days ˚C N/mm2 % % % ˚C Minutes N/cm2 % % ˚C ˚C % ˚C ˚C % Days ˚C mg/cm2 ˚C ˚C Hours mg/cm2 ˚C Hours % M.0 150±2 70±2 240 – 7 135±3 – ±25 – ±25 200±3 15 20 175 15 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 85±2 336 (14 days) 1.Insulation Material Characteristics Sl.3 10 15 3 4 5 6 7 8 9 10 11 12 13 14 N/A 130±3 N/A 1 N/A 4 0.002 (90˚C) 1011(20˚C) 25±2 24 250 to 300 <0. followed by Tensile Strength and Elongation at break No. permanent elongation after cooling Low temperature bend test: Temperature at which specimen shall not crack Low temperature elongation test: Test temperature Minimum Elongation Low temperature impact test: Temperature at which specimen shall not crack Pressure test at high temperature: Test temperature Maximum indentation Loss of Mass (only for T11 insulation as per BS) Ageing: Number of days Ageing Temperature Maximum loss of mass Resistance to cracking (Heat shock test) Temperature at which the specimen shall not crack Water absorption – electrical method Temperature at which specimen shall not crack Duration Maximum variation of mass Maximum permissible shrinkage: – Temperature – Duration Maximum permissible shrinkage Insulation Resistance const (Ki) at max.5 4.67 (90˚C) 1010(70˚C) 1012(90˚C) N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 15 OCI/PBTB/Rev-001/010909 .cm ˚C Hours ppm % (µS/mm) 7 100±2 12.5 150 XLPE (0.45/. variation of tensile strength from unaged specimen Max.5 200 LSF (0. 1 2 Description Tensile Strength and Elongation at break Min. elongation at break Accelerated ageing for specified period at specified temp.Ohm. of days ageing Ageing temperature Max. elongation under load Max.5 ±25 150 ±25 N/A N/A N/A N/A N/A -15±2 -15±2 20 N/A 80±2 50 7 80±2 2. tensile strength Min.Km Ohm.0 7 135±3 – ±30 – ±30 200±3 15 20 100 25 -15±2 -15±2 30 -15±2 110±2 50 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 0. No.6/1 kV) 12. variation of elongation from unaged specimen Hot Set Test: – Temperature – Time under load – Mechanical stress Max. rated temp. Volume Resistivity at maximum rated temperature Ozone Resistance test Temperature at which specimen shall not crack Duration Ozone Concentration Acidic (corrosive) gases evolved Level of HCl pH (minimum) Conductivity (maximum) Unit N/mm2 % PVC (Type A) 12. elongation at break 2 Accelerated ageing for specified period at specified temp. variation of tensile strength from unaged specimen Minimum Elongation Max. variation in elongation at break 12 Acidic (corrosive) gases evolved Level of Hcl pH (minimum) Conductivity (maximum) !) 2) 16 OCI/PBTB/Rev-001/010909 Unit PVC (ST2/Type 9) 12. followed by Tensile Strength and Elongation at break No. 99.5 ±25 150 ±25 -15±2 -15±2 20 -15±2 90±2 50 150±2 7 100±2 1. see Table in Page 20 . variation of elongation from unaged specimen 3 Low temperature bend test: Temperature at which specimen shall not crack 4 Low temperature elongation test: Test temperature Minimum Elongation 5 Low temperature impact test: Temperature at which specimen shall not crack 6 Pressure test at high temperature: Test temperature Maximum indentation 7 Resistance to cracking (Heat shock test) Temperature at which the specimen shall not crack 8 Loss of Mass Ageing: Number of days Ageing Temperature Maximum loss of mass 9 Water absorption No. of days ageing Ageing temperature Minimum tensile strength after ageing Max. Description No.1) Aging temperature Number of days aging Max variation in tensile strength Max.5 150 LSF N/mm2 % 10 100 Days ˚C N/mm2 % % % ˚C ˚C % ˚C ˚C % ˚C Days ˚C mg/cm2 Hours ˚C mg/cm2 N/mm ˚C Days % % % (µS/mm) 7 100±2 12. see Table in Page 20 For Special Characteristics of PVC Sheathing.5 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 7 100±2 10 40 100 40 -15±2 -15±2 30 -15±2 80±2 50 N/A N/A N/A N/A 24 70±2 10 5 7 70±2 30 30 <0. 1 Tensile Strength and Elongation at break Min. of days ageing Aging Temperature Maximum increase in mass 10 Tear Resistance test to B5 6469 (sec 99.1) Minimum Value 11 Water immersion test to BS 6469 (sec. tensile strength Min.5 4.Sheathing Material Characteristics Sl.3 10 For Characteristics of PE Sheathing material. Special PVC Compounds with additional requirements provided by OCI: Property FR Oxygen Index (Min.) Temperature Index (Min) Smoke Density (Max.) Acid Gas Generation (Max.) Flammability Test* 30 250 – – IEC 60332-1 and IEC 60332-3-24 Material FRLS 30 250 60 20% IEC 60332-1 and IEC 60332-3-24 FRRT 30 250 – 17% IEC 60332-1 and IEC 60332-3-24 *Based on specific requests, we can provide compounds which can meet flammability requirements of IEC 60332-3-23 and IEC 60332-3-22 Properties of Polyethylene Sheathing Material: Properties Dissipation factor 60 Hz 103 Hz 106 Hz Arc resistance, s (ASTM D495) Density, g/cm3 Modulus of elasticity in tension, psi x 105 Percent elongation, % (ult.) (Max.) Tensile strength, yield, psi x 102 Compressive strength, psi x 103 Rockwell hardness Impact strength, ft-Ib/in. Heat distortion temperature (at 66 psi), ˚F Thermal conductivity, cal/cm.s. ˚C x 10-4 Thermal expansion, in./in. per ˚C x 10-5 Water absorption, % Burning rate LDPE 0.0002 0.0002 0.0002 Melts 0.910-0.925 0.17-0.35 300 14-19 – R10 – 105-121 8 11-30 <0.02 Slow MDPE 0.0002 0.0002 0.0002 Melts 0.926-0.940 0.25-0.55 300 19-26 – R15 – 120-150 – 15-30 <0.02 Slow HDPE 0.0002 0.0002 0.0002 > 125 0.941-0.965 0.8-1.5 400 26-45 2.4 R30-R50 1-23 140-185 11-12 15-30 <0.01 Slow 17 OCI/PBTB/Rev-001/010909 OCI can supply installing cables with special requirements for the following Utility SEC-EOA Voltage Rating 35 KV * * * Requirement Swellable tape under and over metallic screen. Metal polyethylene laminate over metallic screen. Polyethylene or PVC Outer Sheath. ARAMCO 10 kV to 35 kV Optional Requirement: * Watertight Conductor with TR-XLPE Insulation * Semi-conducting water blocking swellable tapes under and over the metallic screen or concentric neutral. * Plastic coated laminated aluminium or copper tape under the outer jacket and firmly bonded to it. * * * Water swellable tape over copper tape screen Water Swellable tape over 3 core assembly Polyethylene bedding under Armour and PVC Outer Sheath SABIC 5 to 35 kV DEWA 11 and 33 kV Single Core: * Watertight Conductor * Swellable tape in metallic screen region. * Metal polyethylene laminate in metallic screen region. * Polyethylene Outer Sheath. Multi Core: * Watertight Conductor * Swellable tape in metallic screen region. * Metal polyethylene laminate in metallic screen region. * Polyethylene Outer Sheath over steel wire armour Single Core: * Watertight Conductor * Water swellable tape over insulation screen * Non-conductive water swellable tape over copper screen * Copolymer Coated Laminated Tape * Polyethylene Outer Sheath 33 * * * * * kV Cables 3 Core Cables: Watertight conductor TR-XLPE insulation. Polyethylene inner sheath Polyethylene outer sheath over steel tape armour Armour: Galvanized steel + tinned copper wires. Conductivity of copper wires alone shall be at least 50% of any phase conductor at normal working temperature and shall not be less than 25% of the total number of armour wires. Armour to be embedded and covered by material suitable to prevent movement of water traversely. FEWA 33 kV ADWEA 33 kV KAHRAMAA 0.6/1 kV * 18 OCI/PBTB/Rev-001/010909 Utility KAHRAMAA Voltage Rating 11 KV * * * * Requirement Fillers of non-hygroscopic material to inhibit flow of water. Armour to be embedded in or overlaid by substance or material to inhibit flow of water. 3 Core 11 kV Cable without Metallic Screen over individual cores. Steel Wire armour over Semi-conductivity bedding. Swellable tape under and over insulation screen PVC outer sheath KUWAIT 11 kV SYRIA IRAQ 12 to 20 kV 11 to 33 kV * * Single Core: * Waterproof tape over metallic screen * PVC outer sheath Three core: * Extruded EPR fillers * Waterproof tape over bedding. * PVC outer sheath over steel tape armour Single Core * Swellable tapes over metallic screen * PE (ST7) outer sheath Single Core: * Longitudinally watertight at metallic screen * Radial Watertightness to be ensured by Outer sheath. JORDAN 33 kV TUNISIA 10 to 30 kV 19 OCI/PBTB/Rev-001/010909 Unarmoured Amp Flat Touching 167 203 243 303 369 426 481 550 647 739 837 1000 1154 1310 1454 20 OCI/PBTB/Rev-001/010909 . Unarmoured Amp Trefoil 132 157 186 227 271 308 343 387 447 504 564 617 683 757 823 Amp Flat Touching duct 133 159 188 229 274 311 347 391 453 510 571 647 728 801 873 Amp Trefoil 163 198 238 296 361 417 473 543 641 735 845 952 1067 1221 1346 In Air Single core.Current Ratings for Voltage grade from 6 kV to 30 kV Basic Assumption:Conductor Material – Copper Single Core Cables (Unarmoured) Ground Temperature – 20˚C Air Temperature – 30˚C Thermal resistivity of soil – 150˚C-cm/w Depth of Laying – 800 mm Double point bonding. Unarmoured Size Amp Trefoil 25 35 50 70 95 120 150 185 240 300 400 500 630 800 1000 140 166 196 239 285 323 361 406 469 526 590 649 718 796 865 Amp Flat spaced 144 172 203 246 293 332 366 410 470 524 572 680 766 842 918 In Single way Duct Single core. Flat spacing – 2 OD from centre to centre Ground Single core. Armoured Amp Trefoil 147 178 214 266 325 375 426 489 577 662 761 857 961 1099 1212 Amp Flat spaced 150 183 219 273 332 383 433 495 582 665 753 900 1039 1179 1309 21 OCI/PBTB/Rev-001/010909 .Current Ratings for Voltage grade from 6 kV to 30 kV Basic Assumption:Conductor Material – Copper Single Core Cables (Armoured) Ground Temperature – 20˚C Air Temperature – 30˚C Thermal resistivity of soil – 150˚C-cm/w Depth of Laying – 800 mm Double point bonding. Flat spacing – 2 OD from centre to centre Ground Single core. Armoured Size Amp Trefoil 25 35 50 70 95 120 150 185 240 300 400 500 630 800 1000 126 149 176 215 257 291 325 365 422 473 531 584 646 717 779 Amp Flat spaced 130 155 183 221 264 299 329 369 423 472 515 612 689 758 826 In Single way Duct Single core. Armoured Amp Trefoil 119 141 167 204 244 277 309 348 402 454 508 556 615 681 741 Amp Flat spaced 120 143 169 206 247 280 312 352 408 459 514 582 656 721 786 In Air Single core. Unarmoured Size Amp Trefoil 25 35 50 70 95 120 150 185 240 300 400 500 630 800 1000 108 129 152 186 221 252 281 317 367 414 470 527 588 666 735 Amp Flat spaced 112 134 157 192 229 260 288 324 373 419 466 540 616 691 766 In Single way Duct Single core. Unarmoured Amp Trefoil 127 154 184 230 280 324 368 424 502 577 673 760 875 1019 1144 Amp Flat Touching 130 157 189 236 287 332 376 432 511 586 676 799 932 1077 1221 22 OCI/PBTB/Rev-001/010909 . Unarmoured Amp Trefoil 102 122 144 176 210 240 267 303 351 397 451 501 559 633 699 Amp Flat Touching duct 103 123 146 178 213 242 271 307 356 402 457 514 586 657 728 In Air Single core.Current Ratings for Voltage grade from 6 kV to 30 kV Basic Assumption:. Flat spacing – 2 OD from centre to centre Ground Single core.Conductor Material – Aluminium Single Core Cables (Unarmoured) Ground Temperature – 20˚C Air Temperature – 30˚C Thermal resistivity of soil – 150˚C-cm/w Depth of Laying – 800 mm Double point bonding. Armoured Amp Trefoil 92 110 130 158 189 216 240 273 316 357 406 451 503 570 629 Amp Flat spaced 93 111 131 160 192 218 244 276 320 362 411 462 527 591 656 Amp Trefoil 114 139 166 207 252 292 331 382 452 519 606 684 788 917 1030 In Air Single core. Armoured Size 25 35 50 70 95 120 150 185 240 300 400 500 630 800 1000 Amp Trefoil 97 116 137 167 199 227 253 285 330 373 423 474 529 599 662 Amp Flat spaced 101 121 141 173 206 234 259 292 336 377 419 486 554 622 689 In Single way Duct Single core. Flat spacing – 2 OD from centre to centre Ground Single core.Current Ratings for Voltage grade from 6 kV to 30 kV Basic Assumption:Conductor Material – Aluminium Single Core Cables (Armoured) Ground Temperature – 20˚C Air Temperature – 30˚C Thermal resistivity of soil – 150˚C-cm/w Depth of Laying – 800 mm Double point bonding. Armoured Amp Flat spaced 117 141 170 212 258 299 338 389 460 527 608 719 839 969 1099 23 OCI/PBTB/Rev-001/010909 . Current Ratings for Voltage grade from 6 kV to 30 kV Basic Assumption:Conductor Material – Copper Three Core Cables Ground Temperature – 20˚C Armoured/Unarmoured Air Temperature – 30˚C Thermal resistivity of soil – 150˚C-cm/w Depth of Laying – 800 mm Double point bonding Ground In Single way Duct In Air Size Amp Amp Amp Amp Armoured 112 134 158 194 232 264 296 335 387 435 492 Amp Unarmoured 142 170 204 253 304 351 398 455 531 606 696 Amp Armoured 143 172 205 253 307 352 397 453 529 599 683 Unarmoured Armoured Unarmoured 25 35 50 70 95 120 150 185 240 300 400 129 153 181 221 262 298 334 377 434 489 553 129 154 181 220 263 298 332 374 431 482 541 112 133 158 193 231 264 297 336 390 441 501 24 OCI/PBTB/Rev-001/010909 . Current Ratings for Voltage grade from 6 kV to 30 kV Basic Assumption:Conductor Material – Aluminium Three Core Cables Ground Temperature – 20˚C Armoured/Unarmoured Air Temperature – 30˚C Thermal resistivity of soil – 150˚C-cm/w Depth of Laying – 800 mm Double point bonding Ground Size Amp Amp In Single way Duct Amp Amp Armoured Amp Unarmoured In Air Amp Armoured Unarmoured Armoured Unarmoured 25 35 50 70 95 120 150 185 240 300 400 100 119 140 171 203 232 260 294 340 384 438 100 119 140 171 204 232 259 293 338 380 432 87 103 122 150 179 205 231 262 305 346 398 87 104 123 150 180 206 231 262 304 343 393 110 132 158 196 236 273 309 355 415 475 552 111 133 159 196 238 274 309 354 415 472 545 25 OCI/PBTB/Rev-001/010909 . 5 K.5 2.6/1 kV .0.8 m Ambient Air temperature: 30˚C Area Single core Trefoil mm2 Unarmoured 1.5 4 6 10 16 25 35 50 70 95 120 150 185 240 300 400 500 630 800 1000 27 37 48 60 82 112 151 178 214 273 338 396 456 529 632 731 852 986 1139 1293 1443 Armoured 27 37 48 60 82 112 151 178 222 283 348 403 464 533 628 715 817 924 1041 1131 1227 Unarm 27 37 48 62 82 119 150 185 226 286 353 412 471 546 651 752 875 Armoured 30 39 53 67 91 121 157 194 234 294 363 420 479 553 653 744 856 In Air Two Core In Ground Single core Two core Trefoil Armoured 28 38 50 63 83 109 141 166 198 241 288 327 365 411 473 528 573 635 698 737 782 Armoured 34 43 57 71 95 123 160 190 224 272 326 371 416 469 541 607 670 In Duct Single core Trefoil Armoured 27 37 48 61 82 106 140 159 200 241 283 317 343 375 419 458 486 527 569 593 623 Two core Armoured 29 38 49 62 82 106 135 162 193 237 286 322 362 411 476 535 604 26 OCI/PBTB/Rev-001/010909 . XLPE insulated Armoured/Unarmoured Cables Thermal Resistivity of Soil: 1.1C & 2 Core Copper.m/W Ground temperature: 20˚C Depth of laying: 0. 5 K.5 2.0. XLPE insulated Armoured/Unarmoured Cables Thermal Resistivity of Soil: 1.5 4 6 10 16 25 35 50 70 95 120 150 185 240 300 400 500 630 800 1000 21 29 37 48 64 88 115 144 158 203 251 292 337 393 469 544 596 658 747 844 948 Armoured 21 29 37 48 64 88 115 144 166 212 260 301 348 400 474 543 596 658 747 844 948 Unarm 22 29 37 48 64 89 111 136 165 210 259 288 329 377 445 500 575 Armoured 22 29 37 48 64 91 117 143 173 218 268 288 329 377 445 500 575 In Air Two Core In Ground Single core Two core Trefoil Armoured 22 31 40 50 65 85 110 128 152 185 220 251 280 317 367 403 412 438 497 562 631 Armoured 23 32 41 51 70 95 121 143 170 206 247 268 306 351 408 453 488 In Duct Single core Trefoil Armoured 22 31 38 47 65 83 107 128 154 187 221 249 273 300 340 375 351 376 427 483 542 Two core Armoured 21 27 35 44 58 81 102 123 146 180 216 243 269 308 352 391 442 27 OCI/PBTB/Rev-001/010909 .8 m Ambient Air temperature: 30˚C Area Single core Trefoil mm2 Unarmoured 1.m/W Ground temperature: 20˚C Depth of laying: 0.6/1 kV .1C & 2 Core Aluminium. 3 and 4 Core Copper and Aluminium XLPE insulated cables Thermal Resistivity of Soil: 1.5 4 6 10 16 25 35 50 70 95 120 150 185 240 300 400 Unarmoured Copper 23 33 41 53 71 103 129 158 193 246 303 354 406 469 559 645 749 Aluminium 18 25 32 41 55 78 97 119 145 184 228 266 304 353 420 487 514 In Air Armoured Copper 25 34 45 57 79 103 134 165 201 252 311 361 413 475 561 639 735 Aluminium 18 25 32 41 55 78 102 124 151 190 234 272 311 360 426 488 514 28 37 49 60 81 104 133 158 188 228 273 311 348 392 453 507 560 In Ground Armoured Copper Aluminium 21 27 36 45 59 80 102 120 143 174 209 238 266 302 350 395 425 24 32 41 52 69 89 113 136 162 199 240 271 305 345 399 448 515 In Duct Armoured Copper Aluminium 18 23 29 38 50 68 87 103 123 152 183 208 234 266 309 349 372 28 OCI/PBTB/Rev-001/010909 .5 2.8 m Ambient Air temperature: 30˚C Area mm2 1.6/1 kV .0.m/W Ground temperature: 20˚C Depth of laying: 0.5 K. 0.6/1 kV .m/W Ground temperature: 20˚C Depth of laying: 0.5 K.8 m Ambient Air temperature: 30˚C Area Single core Trefoil mm2 Unarmoured 1.5 4 6 10 16 25 35 50 70 95 120 150 185 240 300 400 500 630 800 1000 23 31 40 51 69 94 127 150 173 219 273 318 365 423 505 583 679 782 900 1018 1134 Armoured 23 31 40 51 69 94 127 150 181 228 280 326 371 425 500 571 649 729 817 881 949 Unarm 23 31 40 52 68 91 122 149 182 229 284 330 378 436 519 598 695 Armoured 23 31 41 53 72 96 128 156 189 237 293 338 384 445 525 598 685 In Air Two Core In Ground Single core Two core Trefoil Armoured 25 33 43 55 72 95 123 144 170 206 246 280 312 351 403 450 488 536 586 614 648 Armoured 28 36 48 59 79 102 135 161 191 232 279 316 354 401 462 517 569 In Duct Single core Trefoil Armoured 23 32 42 53 71 92 122 139 169 204 239 264 290 315 352 385 410 439 473 493 516 Two core Armoured 24 31 41 51 69 89 115 138 164 201 242 273 306 348 402 451 508 29 OCI/PBTB/Rev-001/010909 .1C & 2 Core Copper. PVC insulated cables Thermal Resistivity of Soil: 1.5 2. PVC insulated cables Thermal Resistivity of Soil: 1.1C & 2 Core Aluminium.5 K.8 m Ambient Air temperature: 30˚C Area Single core Trefoil mm2 Unarmoured 16 25 35 50 70 95 120 150 185 240 300 400 500 630 800 1000 74 97 121 129 164 202 236 271 315 376 436 500 552 627 709 796 Armoured 74 97 121 133 166 205 239 272 317 375 431 500 552 627 709 796 Unarm 70 90 110 134 169 209 242 276 316 374 420 483 Armoured 72 92 113 136 174 213 242 276 316 374 420 483 In Air Two Core In Ground Single core Two core Trefoil Armoured 74 96 111 129 156 188 213 239 271 313 352 359 381 432 489 549 Armoured 78 101 120 142 175 210 233 266 305 355 394 425 In Duct Single core Trefoil Armoured 72 93 111 133 163 192 216 240 262 298 329 305 327 371 420 472 Two core Armoured 68 86 103 122 152 182 212 234 267 306 340 384 30 OCI/PBTB/Rev-001/010909 .6/1 kV .0.m/W Ground temperature: 20˚C Depth of laying: 0. 5 4 6 10 16 25 35 50 70 95 120 150 185 240 300 400 31 OCI/PBTB/Rev-001/010909 .8 m Ambient Air temperature: 30˚C Area mm 2 In Air Unarmoured Copper Aluminium 15 21 26 35 46 59 78 96 117 149 183 212 243 281 336 387 431 20 28 35 45 59 79 103 128 156 197 243 284 324 374 446 512 593 Armoured Copper 20 26 36 45 62 82 109 133 162 205 252 291 334 383 451 514 589 Aluminium 15 21 26 35 46 61 80 98 120 151 188 218 248 288 344 396 431 In Ground Armoured Copper 23 30 41 51 67 87 113 135 159 195 234 266 298 336 388 434 477 Aluminium 18 23 31 39 51 66 86 102 121 148 179 204 228 259 302 341 370 20 26 34 43 58 75 96 115 137 170 204 230 258 293 338 379 433 In Duct Armoured Copper Aluminium 16 20 26 33 43 56 72 87 104 129 156 176 197 225 264 299 323 1.3C and 4 Core Copper and Aluminium PVC insulated cables Thermal Resistivity of Soil: 1.5 2.6/1 kV .m/W Ground temperature: 20˚C Depth of laying: 0.5 K.0. 91 0.91 0.97 0.87 50 0.98 0.04 1.91 0.5 3 Nominal conductor size ≤185 mm 1.04 25 0.93 35 0.88 0.93 0.85 45 0.82 55 0.91 45 0.04 0.8 m for direct buried cables Single-core cables Depth of laying m 0.89 40 0.86 32 OCI/PBTB/Rev-001/010909 .02 0.5 0.94 0.96 30 0.04 1.75 2 2.5 1.93 0.76 Table 3 – Correction factors for depth of laying Other than 0.03 0.04 35 0.6 1 1.Table 1 – Correction factors for ambient air temperatures other than 30˚C Maximum conductor temperature ˚C 90 Ambient air temperature ˚C 20 1.90 0.76 60 0.08 25 1.25 1.80 50 0.71 Table 2 – Correction factors for ambient ground temperatures other than 20˚C Maximum conductor temperature ˚C 90 Ground temperature ˚C 10 1.90 Three-core cables 1.95 0.06 1.07 15 1.95 0.90 2 >185 mm2 1.96 40 0.98 0.93 0.96 0.96 0.94 0.95 0. 74 0.74 0.32 1.73 0.25 1.93 0.16 1.26 1.75 2 2.18 1.29 1.8 1.29 1.15 1.25 1.75 0.93 0.21 1.88 0.5 K.36 1.7 1.03 1.73 0.81 0.30 1.05 1.89 0.37 0.18 1.27 1.89 0.97 0.5 3 Nominal conductor size ≤185 mm 1.89 0.80 0.36 1.95 0.22 1.82 0.35 1.30 1.92 0.74 0.33 1.17 1.89 0.91 0.73 33 OCI/PBTB/Rev-001/010909 .80 0.19 1.03 0.79 3 0.9 1.23 1.35 1.80 0.89 0.81 0.81 0.96 0.24 1.19 1.24 1.24 1 1.29 1.02 0.92 2 >185 mm2 1.16 1.94 0.74 0.28 1.95 0.22 1.89 0.m/W for direct buried single-core cables Nominal area of conductor mm2 16 25 35 50 70 95 120 150 185 240 300 400 Values of soil thermal resistivity K.98 0.74 0.75 0.34 1.5 0.5 1.80 0.30 1.20 1.81 0.22 1.94 0.Table 4 – Correction factors for depths of laying other than 0.m/W 0.90 Three-core cables 1.88 0.18 1.88 0.28 1.21 1.89 0.74 0.23 1.99 0.95 0.02 0.25 1.19 2 0.75 0.88 Table 5 – Correction factors for soil thermal resistivities other than 1.30 0.91 0.80 0.88 0.04 1.96 0.18 1.5 0.88 0.6 1 1.97 0.28 1.18 1.80 0.16 1.23 1.93 0.88 2.34 1.8 m for cables in ducts Single-core cables Depth of laying m 0. 15 1.21 1.18 1.25 1.82 0.14 1.23 1.91 0.77 0.23 1.83 0.18 1.90 0.21 1.13 1.15 1.8 1.13 1.83 0.5 0.77 0.13 1.19 1.82 3 0.17 1.21 0.91 0.90 0.18 1.17 1.17 1.78 0.78 0.23 1.19 1.24 1.16 1.9 1.m/W 0.12 1.m/W 0.26 1.26 1.14 2 0.16 1.90 0.20 1.28 1.18 1.83 0.16 1.16 1.83 0.77 0.77 0.8 1.21 1.14 1.90 0.22 1.77 0.91 0.15 1.17 1.27 1.83 3 0.83 0.78 0.84 0.12 1.23 1.12 1.17 1.78 0.17 1.19 1.m/W for direct buried three-core cables Nominal area of conductor mm2 16 25 35 50 70 95 120 150 185 240 300 400 Values of soil thermal resistivity K.14 1.19 1.78 0.23 0.18 1.25 1.91 0.91 0.79 0.25 1.90 0.84 0.19 1.91 0.91 0.92 0.78 0.21 1.77 Table 7 – Correction factors for soil thermal resistivities other than 1.21 1.15 1.23 1.91 0.85 0.91 0.14 1.24 1.77 0.28 1.83 0.84 0.77 0.83 0.5 K.28 0.84 0.13 1.20 1.18 1.20 1.83 0.78 0.90 0.90 2.24 1.79 0.78 0.15 1.83 0.11 1.84 0.16 1.22 1.15 2 0.13 1.5 K.m/W single-core cables in buried ducts Nominal area of conductor mm2 16 25 35 50 70 95 120 150 185 240 300 400 Values of soil thermal resistivity K.90 0.7 1.19 1 1.77 0.15 1.13 1.83 0.14 1.83 0.83 0.21 1.85 0.84 0.15 1.18 1.21 1.90 2.84 0.14 1.90 0.22 1.91 0.25 1.21 1.13 1.7 1.Table 6 – Correction factors for soil thermal resistivities other than 1.77 0.14 1.17 1.77 0.17 1 1.79 0.12 1.91 0.26 1.78 0.20 1.14 1.76 34 OCI/PBTB/Rev-001/010909 .91 0.5 0.27 1.22 1.9 1.23 1.90 0.25 0.20 1. 84 0.69 0.8 1.86 0.79 0.16 1.81 0.5 K.83 0.14 1.5 0.59 0.16 1.49 0.7 1.09 1.12 1 1.12 1.82 0.85 0.93 0.08 1.09 1.93 0.88 0.80 0.82 0.11 1.57 0.83 0.11 1.17 1.62 0.77 0.13 1.94 0.60 0.9 1.09 1.86 3 0.84 0.Table 8 – Correction factors for soil thermal resistivities other than 1.93 0.88 0.94 0.87 0.84 0.11 1.94 0.87 0.10 2 0.m/W for three-core cables in ducts Nominal area of conductor mm2 16 25 35 50 70 95 120 150 185 240 300 400 Values of soil thermal resistivity K.51 0.57 0.86 0.15 1.93 0.71 0.10 1.12 1.83 0.80 0.11 1.11 1.89 0.88 0.14 0.13 1.47 0.54 0.14 1.89 0.68 0.12 1.10 1.72 0.12 1.61 0.13 1.78 0.89 0.83 0.87 0.65 0.15 1.14 1.69 0.87 0.11 1.17 0.10 1.78 0.94 0.70 0.m/W 0.09 1.74 0.08 1.14 1.14 1.84 0.12 1.83 0.72 0.94 0.08 1.92 2.83 0.88 0.45 0.16 1.81 Table 9 – Correction factors for groups of three-core cables In horizontal formation laid direct in the ground Number of cables in group 2 3 4 5 6 7 8 9 10 11 12 Spacing between cable centres mm Touching 0.15 1.68 600 0.10 1.88 0.94 0.09 1.94 0.09 1.63 0.84 0.56 400 0.46 0.43 200 0.83 – – – – – 35 OCI/PBTB/Rev-001/010909 .14 1.90 0.88 0.08 1.82 0.92 0.93 0.13 1.77 – – – 800 0.76 0.10 1.69 0.12 1. 94 0.57 0.Table 10 – Correction factors for groups of three-phase circuits of single-core cables laid direct in the ground Number of cables in group 2 3 4 5 6 7 8 9 10 11 12 Spacing between group centres mm Touching 0.41 0.92 0.83 0.72 0.76 0.70 0.63 0.46 0.52 0.86 0.67 0.73 – – – 800 0.60 0.58 0.75 0.55 0.82 0.54 0.77 0.73 0.65 0.36 0.74 0.73 0.86 0.74 0.72 600 0.75 0.80 0.83 0.37 0.51 200 0.79 0.54 0.63 0.61 0.79 0.57 0.88 0.73 0.82 0.81 0.80 – – – 800 0.85 0.35 200 0.91 0.88 0.62 0.73 0.59 0.64 0.81 0.87 0.86 – – – – – 36 OCI/PBTB/Rev-001/010909 .92 0.49 0.39 0.76 0.65 0.67 0.75 0.55 0.83 0.54 0.52 400 0.90 0.43 0.89 0.80 0.95 0.80 – – – – – Table 11 – Correction factors for groups of three-core cables In single way ducts in horizontal formation Number of cables in group 2 3 4 5 6 7 8 9 10 11 12 Spacing between duct centres mm Touching 0.66 0.78 0.84 0.82 0.75 0.68 0.87 0.84 0.65 0.69 0.69 0.85 0.64 600 0.72 0.53 0.64 0.75 0.88 0.61 400 0.68 0.62 0. 70 0.46 0.60 0.57 0.Table 12 – Correction factors for groups of three-phase circuits of single-core cables in single-way ducts Number of cables in group 2 3 4 5 6 7 8 9 10 11 12 Spacing between duct group centres mm Touching 0.77 0.42 0.82 0.82 – – – – – 37 OCI/PBTB/Rev-001/010909 .51 0.71 0.64 0.55 0.66 0.67 600 0.88 0.66 0.78 0.44 0.56 0.78 0.81 0.55 400 0.68 0.58 0.69 0.85 0.75 0.93 0.76 – – – 800 0.70 0.48 0.72 0.86 0.59 0.85 0.67 0.80 0.89 0.40 200 0.43 0.74 0.84 0.83 0.77 0.76 0.61 0.91 0. 00 1. Spaced 1 2 3 1.76 0.87 0.00 0.78 0.87 0.00 1.98 0. 38 OCI/PBTB/Rev-001/010909 . NOTE 2: Factors apply to single layer groups of cables as shown above and do not apply when cables are installed in more than one layer touching each other.66 – – – 0.85 0.96 1.00 1.00 0.71 1 1.85 0.98 0.00 1.76 0.00 0. the factors should be reduced.76 0.88 0.Table 13 – Reduction factors for groups of more than one multicore cable in air – To be applied to the current-carrying capacity for one multi-core cable in free air Method of Installation Touching Cables on perforated trays Spaced Number of trays 1 2 3 1 2 3 Touching 1 2 Cables on vertical perforated trays 1 2 1 2 Cables on ladder supports.00 1. the factors should be reduced.82 0.82 0.87 0.87 0.00 0.71 0.79 0.87 0.95 0.73 0.91 0.72 0.97 1.68 0.93 – – – 3 1. The spread of values is generally less than 5%.80 0.96 0.97 0.91 0.89 0.85 0.00 1.86 0.76 0.70 0.73 0.00 0.70 Number of cables 3 4 6 0.00 1.88 Spaced Touching NOTE 1: Values given are averages for the cable types and range of conductor sizes considered.79 0.96 0.99 0.92 0.80 0. cleats etc.86 1.79 0.77 0.00 1.91 0.00 1.79 0.00 1.76 0.00 1.99 0.73 – – 0.91 0. NOTE 3: Values are given for vertical spacing between trays of 300 mm and at least 20 mm between trays and wall. For closer spacing.00 1.82 0.95 0.73 0.98 1. For closer spacing.00 0.78 0.88 0.00 2 9 0.81 0.98 0.00 1. NOTE 4: Values are given for horizontal spacing between trays of 225 mm with trays mounted back to back.88 0.78 0. Values for such installations may be significantly lower and must be determined by an appropriate method.80 0.88 0.00 1.73 0. 00 0. the factors should be reduced. NOTE 3: Values are given for vertical spacings between trays of 300 mm.90 0. 39 OCI/PBTB/Rev-001/010909 . cleats etc.89 0.96 0.96 0.98 0.93 0.81 formation 0.86 Three cables in horizontal formation Perforated trays (Note 3) Vertical Perforated trays (Note 4) Ladder supports.00 0. NOTE 4: Values are given for horizontal spacing between trays of 225 mm with trays mounted back to back. (Note 3) 1 2 3 1 2 Spaced 1 2 3 1.95 0. (Note 3) 1 2 3 1. NOTE 5: For circuits having more than one cable in parallel per phase.95 0.90 0.00 0. The spread of values is generally less than 5%.00 0.89 0.00 1.97 0.98 0.96 1.93 0.86 Three cables in trefoil formation 1. NOTE 2: Factors are given for single layers of cables (or trefoil groups) as shown in the table and do not apply when cables are installed in more than one layer touching each other.92 0. Values for such installations may be significantly lower and should be determined by an appropriate method.96 1.Table 14 – Reduction factors for groups of more than one circuit of single-core cables (Note 2) – To be applied to the current-carrying capacity for one circuit of single-core cables in free air Method of Installation Number of trays 1 2 3 Number of three-phase Use as a circuits (Note 5) multiplier to 1 2 3 rating for 0.97 0.98 0.97 0.87 0.85 0.96 0.90 NOTE 1: Values given are averages for the cable types and range of conductor sizes considered.94 1. For closer spacing.86 0.78 Touching Perforated trays (Note 3) Touching Ladder supports.93 0. the factors should be reduced. etc.00 0.89 0.00 0. For closer spacing.87 Three cables in horizontal 0. cleats.97 0.91 0. each three phase set of conductors should be considered as a circuit for the purpose of this table.91 0. Permissible short-circuit temperatures and rated short-time current densities 1 Cables with (XLPE Insulation) 2 3 4 5 6 7 8 9 10 Permissible short circuit Conductor temperature at the beginning of short circuit in ˚C temperature in ˚C 90 80 70 60 50 40 30 20 Rated short-time current density in A/mm2 for a rated short-circuit duration of 1 second Copper Conductors Aluminium Conductors 250 250 143 94 149 98 154 102 159 105 165 109 170 113 176 116 181 120 1 Cables with (PVC Insulation) Copper Conductor 2 3 4 5 6 7 8 9 10 Permissible short circuit Conductor temperature at the beginning of short circuit in ˚C temperature in ˚C 90 80 70 60 50 40 30 20 Rated short-time current density in A/mm2 for a rated short-circuit duration of 1 second ≤ 300 mm 300 mm2 2 160 140 – – – – 115 103 122 111 129 118 136 126 143 133 150 140 40 OCI/PBTB/Rev-001/010909 . Permissible Short Circuit current of XLPE insulated power cables (copper conductors) 41 OCI/PBTB/Rev-001/010909 . Permissible Short Circuit current of XLPE insulated power cables (Aluminum conductors) 42 OCI/PBTB/Rev-001/010909 . an annual inspection should be satisfactory. cable should be covered with Masonite or a dark film wrap (to block the sun’s rays and shield them from the elements). 5. In general. 12. If a part length is returned to storage. Cables should be stored in an area away from open fires or sources of high heat. falling or flying objects or other materials will not touch the cable. Reels should be stored in an area where construction equipment. 10. Where the reels are exposed to the weather. 7. 13.Recommended Cables Storage Practices Storage and Storage Maintenance: 1. Cable reels must remain in an upright position. 4. installation date. Cable should be stored in an area where chemicals or petroleum products will not be spilled or sprayed on the cables. If the cables are stored in a secure area and not exposed to the effects of the weather. 43 OCI/PBTB/Rev-001/010909 .Reels must not be stacked. 11. manufacturer. While on the reel. If a length of cable has been cut from the reel. the cable end should be immediately resealed to prevent moisture from entering it. the reel’s protective covering should be restored. Uncovered/unsheltered cable will degrade due to exposure to direct sunlight and/or the elements. Timbers or metal supports must be placed under the reel flanges to provide elevated storage of the reels away from direct contact with water or damp soil. If the reels are exposed in a non-secure area. Moisture and atmospheric conditions can cause exposed conductors to oxidize and discolor. along with all test reports should be kept on file. a bi-monthly inspection should be performed to observe any sign of deterioration. any cable for use indoors should be stored indoors. Finished cables have no established shelf-life. policing of the area at frequent intervals may be required depending on circumstances. there should be no degradation of the insulation. Cables should be stored in a sheltered area. Records of delivery date. If the cables are protected. 6. 14. Cable reels must not be stored on their sides. 3. circumstances. Cable reels should be stored with the protective covering or lagging in place. hard surface so that the flanges do not sink into the earth. Cable reels and lagging must not be stored in direct contact with water or dampness for extended periods of time. Cables stored outdoors should have the ends sealed to prevent moisture ingress into the cable. Wooden reels should be stored off the ground to prevent rotting. Reels should be stored on a flat. The weight of the reel and cable must be carried at all times by the reel flanges. Any cable suitable for installation outdoors is suitable for storage outdoors. 8. 9. any extenuating 2. the same maximum pulling force applies.D2 Factor σ = 50 N/mm2 (Copper Conductor) σ = 30 N/mm2 (Aluminium Conductor) σ = 50 N/mm2 (Copper Conductor) σ = 30 N/mm2 (Aluminium Conductor) K = 9 N/mm2 1) when laying 3 single core cables simultaneously with a common pulling stocking. whereas the pulling force for 3 laid-up single core cables is 3 times that of a single-core and for 3 non-laid-up single core cables is 2 times that of a single core.Guideline for permissible pulling force for laying of low voltage and medium voltage cables: Means of pulling With pulling head attached to conductor With pulling stocking Type of Cables All types of Cables Unarmoured cable1) All Wire armoured Cables Formula P = σ. A P = σ. A P = K. 44 OCI/PBTB/Rev-001/010909 . P = Pull in Newtons A = total cross-sectional area in mm2 of all conductors (screen/concentric conductor not to be included) D = Overall diameter of cable σ = permissible tensile stress of conductor in N/mm2 K = empirically derived factor in N/mm2. Minimum Installation Bending Radius Cables for fixed wiring up to and including 450/750 V: Insulation Conductors Construction Unarmoured Overall diameter (mm) Upto 10 mm 10 to 25 mm Above 25 mm Minimum radius 3Da 4Db 6D XLPE or PVC Copper and Aluminium. ducting or trunking. b 3D for single-core cables with circular stranded conductors installed in conduits.3 kV: Conductor Circular Copper Shaped Copper Solid Alumiuium Construction Both Armoured and Unarmoured Both Armoured and Unarmoured Both Armoured and Unarmoured Minimum radius 6D 8D 8D XLPE and insulated cables 6. Solid or Stranded circular D = overall diameter a 2D for single-core cables with circular stranded conductors installed in conduits. XLPE and PVC insulated cables rated 0.6/1 kV and 1.6 kV to 33 kV: Type of Cable Minimum Radius During Laying Single Core: (a) Unarmoured (b) Armoured Three Core: (c) Unarmoured (d) Armoured Adjacent to joints or terminations 15D 12D 12D 10D 20D 15D 15D 12D 45 OCI/PBTB/Rev-001/010909 .9/3. ducting or trunking. 5/6 kV (IEC). history of breakdowns and the purpose of carrying out the test.7/15 kV (BS) 12/20 kV (IEC) 12. Cable Voltage Designation D. voltage-withstand test. test as per IEC 60502-2 OR BS 6622 mentioned below may be applied for 15 minutes. Note 2: For installations which have been in use. Electrical tests after installation Voltage Test after installation: 1) Insulation test: a) Test for 5 minutes with the phase to phase voltage of the system applied between the conductor and the metallic screen/sheath.c. These tests are intended for cables immediately after installation and not for cables that have been in service.6 kV (BS) 6/10 kV (IEC). Voltage Test: The purpose of the test is to check that the cable laying has been done correctly. 3. storing. a d. Since it can be assumed that the cable insulation has not been damaged as long as the jacket is intact. b) Test for 24 hours with the normal operating voltage of the system.7/22 kV (BS) 18/30 kV (IEC). A conductive layer on the oversheath can assist in this regard. it is necessary that the ground makes good contact with all of the outer surfaces of the oversheath.C.c. environment. test.c. Values should be negotiated taking into account the age. The test voltage is to be applied between each conductor and the armour and/or screens after all terminating and jointing has been completed. 19/33 kV (BS) Note 1: A d.c.D. the same can be checked by a d. but before connection to the system. 6. A direct voltage of 4 kV per millimeter of specified thickness of extruded oversheath shall be applied with a maximum of 10 kV for a period of 1 minute between each metal sheath or metallic screen and the ground. have been accidentally damaged during shipping.8/6. pulling and backfilling. handling. Voltage as per BS 6622 kV 15 25 37 50 76 kV 3. The cable may.7/15 kV (IEC). 8.35/11 kV (BS) 8. test may endanger the insulation system under test. for example. 46 OCI/PBTB/Rev-001/010909 . For the test to be effective.C. 2) DC Testing: As an alternative to a. lower voltages and/or shorter durations may be used.C. Voltage as per IEC 60502 (4Uo) kV 14 24 35 48 72 D. unless changes are made in the cable materials or manufacturing processes which might change the performance characteristics. Tests: Shall be as per attached Table for Cables. after they have been made. Tests: a) Measurement of electrical resistance of conductors b) Voltage tests c) Partial Discharge test (for XLPE cables with rated voltages 6 kV and above) 2) Sample Tests: Tests made by the manufacturer on samples of completed length or components taken from a completed cable.Definition of Tests for Cables 1) Routine Tests: Tests made by the manufacturer on each manufactured length of cable to check that each length meets the specified requirements. Tests: a) Conductor examination b) Check of dimensions c) 4 hour voltage test for cables with rated voltage 6 kV and above d) Hot set test for XLPE insulation. a type of cable covered by IEC standard. at a frequency. to verify that the finished product meets the specified requirements. 47 OCI/PBTB/Rev-001/010909 . Note: These tests are such that. in order to demonstrate satisfactory performance characteristics to meet the intended application. need not be repeated. 3) Type Tests: Tests made before supplying on a general commercial basis. conductivity. Measurement of volume resistivity for XLPE insulation 4 hours voltage test (4Uo) Determining the mechanical properties of insulation before and after ageing Determining the mechanical properties of non-metallic sheath before and after ageing. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Measurement of electrical resistance of conductor Voltage test (2. Description of the Test Routine Sample Type Elec. Sample and Type tests for LV Cables Test Designation No.5Uo + 2 kV) Measurement of thickness of insulation and non-metallic sheaths Measurement of Cable armour dimensions Measurement of Cable overall diameter Hot set test for XLPE insulation Insulation resistance measurement at normal and operating temp. Ageing tests on pieces of complete cable to check compatibility Loss of mass test on PVC sheath Pressure test at high temperature on sheaths Heat shock test for PVC sheaths Tests on PVC sheaths at low temperature Water absorption test for XLPE insulation Shrinkage test for XLPE insulation Carbon black content of PE sheaths Test under fire conditions (if required) Smoke emission test for Halogen free cables Acid Gas emission test for Halogen free cables pH. fluorine content test for Halogen free cables Water absorption test for halogen free sheath Non Elec. 48 OCI/PBTB/Rev-001/010909 .List of Routine. followed by partial discharge test Impulse withstand test followed by a power frequency voltage test 4 hours Voltage test (4Uo) Resistivity of semiconducting layers Insulation resistance measurement at normal and operating temp. Determining the mechanical properties of insulation before and after ageing Determining the mechanical properties of non-metallic sheath before and after ageing Ageing tests on pieces of complete cable to check compatibility Loss of mass test on PVC sheath Pressure test at high temperature on sheaths Heat shock test for PVC sheaths Tests on PVC sheaths at low temperature Water absorption test for XLPE insulation Shrinkage test for XLPE insulation Shrinkage test for PE outer sheath Strippability test (for strippable insulation screen only) Carbon black content of PE sheaths Test under fire conditions (if required) Water penetration test (if required) Non Elec. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Measurement of electrical resistance of conductor Partial discharge test Voltage test (3.List of Routine. No. Description of the Test 49 OCI/PBTB/Rev-001/010909 .5Uo) Measurement of thickness of insulation and non-metallic sheaths Measurement of armour dimensions Measurement of Cable overall diameter Hot set test for XLPE insulation Bending test followed by partial discharge Tangent Delta Measurement Heating cycle voltage test. Sample and Type tests for MV Cables Test Designation Routine Sample Type Elec. smaller systems will remain steady because the capacity and absorption currents drop to zero faster than on large systems. c) As a preventive maintenance task d) For Trouble shooting Method of Measurement IR is measured by applying voltage (generally stabilised DC) cross a dielectric. For a cable length of L. 50 OCI/PBTB/Rev-001/010909 . and vice versa. consistency must be maintained because electrical insulation will exhibit dynamic behavior during the course of the test. 2) Insulation resistance is temperature-sensitive. insulation resistance decreases.) During this interval. The resistance measurement is in megohms. (mm) L = Length of cable in cm. Larger insulation systems will show a steady decrease. the resistance reading should drop or remain relatively steady. whether the dielectric is “good” or “bad” To evaluate a number of test results on the same piece of equipment. to check proper installation. each and every time. Precautions – 1) When performing insulation resistance testing. Let’s clarify our use of the term “current. the test voltage is applied for 1 min. When temperature increases. measuring the amount of current flowing through the dielectric and then calculating resistance. the test should be conducted the same way and under the relatively same environmental parameters. After connection. After 1 minute the reading should be recorded.” We’re talking about leakage current. IR = VR 2 L Where π x Loge ( D ) d VR = Volume Resistivity of Insulation in ohm – cm D = Outer dia over insulation (mm) d = Inner dia of insulation. (This is a standard industry parameter that allows the client to make relatively accurate comparisons of reading from past tests done by other technicians.Insulation Resistance – Significance and Use Insulation Resistance (IR) evaluates Insulation integrity IR is used as: a) A Quality Tool at the time of manufacturing of cable b) After installation. IR = Insulation Resistance in ohms. ohm-km) at 20˚C 895 840 700 590 475 385 390 335 320 295 255 245 260 265 245 230 230 225 235 51 OCI/PBTB/Rev-001/010909 .6/1 kV XLPE Insulated and PVC Insulated Cables: Size mm2 1.Calculated Minimum Insulation Resistance Values for 0.5 2.5 4 6 10 16 25 35 50 70 95 120 150 185 240 300 400 500 630 PVC Insulated Cables (M.ohm-km) at 20˚C 10 9 8 7 7 6 5 5 5 5 5 5 5 5 5 5 5 5 5 XLPE Insulated Cables (M. ohm-km 845 765 680 600 530 480 445 405 370 360 345 330 295 10 kV M.ohm-km 1060 970 870 770 685 625 580 530 470 430 385 350 310 15 kV M.Calculated Minimum Insulation Resistance Values for Medium Voltage XLPE Insulated Cables: Minimum Insulation Resistance at 20˚C Size (mm2) 25 35 50 70 95 120 150 185 240 300 400 500 630 6 kV M.ohm-km – – 1590 1435 1300 1205 1130 1045 945 875 795 725 655 52 OCI/PBTB/Rev-001/010909 .ohm-km 1300 1185 1075 955 855 785 730 670 600 550 495 450 400 20 kV M.ohm-km – 1365 1240 1110 995 910 855 785 705 650 590 535 480 30 kV M. What is voltage drop? A voltage drop in an electrical circuit normally occurs when current is passed through the wire. 3. How much voltage drop is acceptable? The National Electrical Code states that a voltage drop of 4% at the furthest receptacle in a branch wiring circuit is acceptable for normal efficiency. Heating at a high resistance connection/splice may result in a fire at high ampere loads. The wire does not meet code standards (not heavy enough gauge for the length of the run). What are the consequences of “excess” voltage drop in a circuit? Excess voltage drop can cause the following conditions: 1. Is there air flow to dissipate the heat? 3. the higher the voltage drop. resistance of connector. does a circuit become hazardous? That would depend on how much current is flowing through the high resistance connector. At what % of voltage drop. The greater the resistance of the circuit. 2. In a 120 volt 15 ampere circuit.8 volt drop (115. this means that there should be no more than a 4. Low voltage to the equipment being powered. and the following factors:1. usually caused by:• poor splices anywhere in the circuit • loose or intermittent connections anywhere in the circuit • corroded connections anywhere in the circuit • Inadequate seating of wire in the slot connection on backwired “pushin-type” receptacles and switches. Is the area around the connection insulated. High resistance connections at wiring junctions or outlet terminals. causing improper. so that heat cannot escape. 2. erratic.2 volts) What causes “excess voltage drop” in a branch circuit? The cause is usually: 1. 53 OCI/PBTB/Rev-001/010909 . or no operation – and damage to the equipment. Is the high resistance connection in contact with a combustible material? 2. Poor efficiency and wasted energy. 165 0.Voltage Drop The size of every bare conductor or cable conductor should be such that the drop in voltage from consumer’s terminals to any point in the installation does not exceed 4% of the declared or nominal voltage when the conductors are carrying full load.15 0.76 7.804 4.607 0.211 0.86 4.5 4 6 10 16 25 35 50 70 95 120 150 185 240 300 400 500 630 800 1000 Permissible Voltage Drop (Vp) (Single Core Cables) mV/A/m – – – – 4.18 6.179 0.418 0.373 0. The approximate voltage drop in average circuits such as lighting and domestic heating loads for XLPE insulated cables is: Conductor crosssectional area mm2 1.86 1.36 10.54 1.72 16.0 0.67 2.255 0.223 0. This requirement shall not apply to wiring fed from extra low voltage secondary of a transformer.446 0.94 1.304 0.144 Permissible Voltage Drop (Vp) (Two Core Cables) mV/A/m 30.162 0.612 1.618 1.197 0.351 0.05 2.04 2.244 – – – – – – Permissible Voltage Drop (Vp) (3 & 4 Core Cables) mV/A/m 26.142 – – 54 OCI/PBTB/Rev-001/010909 .866 0.616 0.456 0.86 18.5 2.516 0.348 1.295 0.185 0.267 0.874 0. but disregarding the starting conditions.165 0.362 0.151 0.166 0.173 0.9 11.702 0.316 0.55 1. Hence.Selection of Cable Size Based on Voltage Drop: Based on the required ampacity and installation conditions. cable size 95 mm2 may be selected. permissible voltage drop (say 4%) System voltage (say 415 V) Length in meters Current in Amps Suppose a 300 meters 3 core XLPE insulated cable is to carry 100 Amps and the supply voltage is 415 V then Vcal = 4 x 1000 x 415 = 0. cross-checked with the voltage drop as follows: Vcal = where: Vp = V = L = I = Vp x 1000 x V I x L x 100 Max.553 mV/A/m.553 is to be selected. 55 OCI/PBTB/Rev-001/010909 . Therefore a cable size whose voltage 100 x 300 x 100 drop is less than 0. a suitable cable size is chosen. for the case above . Cross Bonding Induced Voltage Distribution Most popular system of earthing for long circuits. short lengths circuit length upto 1 Km. Induced voltage is proportional to length of cable and so limitations on circuit length. each at crossing. Ampacity is like single point bonded system but costly installations due to requirement of more number of Surge limiters. Long length circuits Both Ends Bonded Single point bonded Surge arrester Earth continuity wire Induced Voltage Distribution Most safe but due to circulating current ampacity reduces Induced Voltage Distribution More ampacity. Surge arrester required at open end. 56 OCI/PBTB/Rev-001/010909 .Bonding and Earthing Methods Method Both Ends Bonded Single point bonded Cross Bonding Induced Voltage at Cable ends No Yes Only at cross bonding points Sheath voltage limiters required No Yes Yes Application Substations. 11. Heat dissipation slower as Thermal Resistivity is 7˚C m/w.92 and easier to install. 3.Comparison of XLPE & PVC Insulated Power Cables PVC Operating Conductor Temperature: 70˚C Lower current carrying capacity. Maximum Temperature Limit under short circuit: 160˚C Lower emergency overload capacity.004 Installation Technique: simple. 5. 57 OCI/PBTB/Rev-001/010909 . Insulation dissipation heat faster as Thermal Resistivity is 3. High moisture resistance. Higher “Loss angle” of 0. Maximum Temperature Limit under short circuit: 250˚C Higher emergency overload capacity. Heavier as specific gravity is 1. Insulation Resistance almost 1000 times higher Higher properties to withstand vibration and heat impacts.01 Installation Technique: simple XLPE Operating Conductor Temperature: 90˚C Higher current carrying capacity. 4. 7. Lower moisture resistance Insulation Resistance Lower Inferior properties to withstand vibration & heat impacts. 6. 1.5˚Cm/w. 8. 9.42. Lighter as specific gravity is 0. 2. Lower “Loss angle” of 0. therefore more difficult to install. 10. 8 1.6 1.2 2.7 1.4 2.4 2.1 1.7 0.7 0.0 2.0 2.8 3.6) kv mm – – 2.5 4 and 6 10 and 16 25 and 35 50 and 70 95 and 120 150 185 240 300 400 500 to 800 1000 Nominal thickness of insulation at rated voltage Uo/U (Um) 0.5 and 2.0 Note: Any conductor cross-section smaller than those given in this table is not recommended Nominal thickness of XLPE Insulation as per IEC 60502-1 Nominal cross-sectional area of conductor mm2 1.2 2.8 2.4 2.6 2.2 2.2 2.0 2.2) kV mm 0.5 and 6 and 16 and 35 50 70 and 95 120 150 185 240 300 400 500 630 800 1000 Nominal thickness of insulation at rated voltage Uo/U (Um) 0.4 2.0 2.0 – – 2.8 2.8 NOTE: Any conductor cross-section smaller than those given in this table is not recommended 58 OCI/PBTB/Rev-001/010909 .0 2.5 4 10 25 and 2.2 2.6/1 (1.2 2.6/1 (1.2 2.0 2.6 2.8/3 (3.2 2.2 2.6 2.4 1.0 1.0 2.6 2.0 2.6) kv mm mm 0.2 1.6 1.8 3.0 1.4 1.7 0.2) kV 1.9 1.Nominal thickness of PVC/A insulation as per IEC 60502-1 Nominal cross-sectional area of conductor mm2 1.8 1.0 2.0 1.8/3 (3.2 1.2 2.0 2.0 2.0 2. 5 3.5 18/30 (36) kV mm – – – – 8.5 5. the maximum electrical stresses applied to the insulation under test voltage.5 3. or the insulation thickness shall be increased in order to limit.4 4.5 3. 59 OCI/PBTB/Rev-001/010909 .2) kV 8.0 Note: Any smaller conductor cross-section than those given in this table is not recommended.0 8.4 – – 2.5) kV 12/20 (24) kV mm mm mm mm 2.5 – 2.6/6 (7.4 4.2) kV 6/10 (7.5 3.5 3.Nominal thickness of XLPE insulation as per IEC 60502-2 Nominal cross sectional area of conductor mm2 10 16 25 35 50 to 185 240 300 400 500 to 1000 Nominal thickness of insulation at rated voltage Uo/U (Um) 3.0 8.5 2.4 4.2 3. at the values calculated with the smallest conductor size given in this table. either the diameter of the conductor shall be increased by a conductor screen.8 3.5 5.4 4.5 5.4 4.4 4.5 2.6 3.5 – – – 2. However.7/15 (17.5 2.5 5.0 3. if a smaller cross-section is needed.0 8.5 5.5 3.0 8.4 4.5 5. Brown Green-Yellow. Blue. Grey Five Core Green-Yellow. Blue Brown. Brown. Yellow. Blue. Blue. Brown Black. Black. Yellow. Grey Green/Yellow. Black Red. Brown. Blue New Core Colour Brown or Blue Brown. Blue. Blue. Grey Blue. BS 6724 Cable Type Single Core Two Core Three Core Four Core Five Core Old Core Colour Red or Black Red. BS 5467. Black. Black. Blue. Grey 60 OCI/PBTB/Rev-001/010909 . Black. Brown. Black. Yellow. Green/Yellow New Core Colour Brown or Blue Brown. Blue. Black. Black Red. Black. Yellow. Black Green and Yellow.Old and New Core BS Core Colours BS 6004 (PVC insulated PVC Sheathed Cables) Cable Type Single Core Two Core Three Core Old Core Colour Red or Black Red. Brown. Brown Green-Yellow. Blue. Blue Brown. Black BS 6346. Grey or Green-Yellow. Brown New Core Colour No Change No Change Green-Yellow. Grey BS 6500 Cable Type Two Core Three Core Four Core Old Core Colour Blue. Black Red. Black. Blue Red. Brown. Overhead conductors are manufactured in a variety of sizes and strandings and several different materials. weight & coefficient of thermal expansion. please refer to our catalogue. These material are compared in the table given below: Material Conductivity Temperature co-efficient for Resistance Co-efficient of linear expansion per ˚C Ultimate tensile strength Modulus of elasticity Typical applications %IACS OHM-MM2/KM 10-6 Mpa Gpa AAC 61 0.96 1100-1344 162 Copper 97 0. stress strain. diameter. We also provide covered conductors. size and dimensions.0036 23 295 70 ACSR 20 0. 61 OCI/PBTB/Rev-001/010909 . Proper conductor selection takes into account the interaction of these characteristics with requirements of lines its voltage. creep & thermal less of strength characteristics. load factor etc. This range of choices enables selection of specific line conductors with characteristics such as conductance. Covered conductors with insulation are good for environments carrying pollution and can withstand contact with conducting materials. capacity. strength.0051 12.00403 23 160-200 70 AAAC 53 0.00331 17 414 125 Short ACSR Low sag and Maximum Span replacement high tensile current with for strength capacity maximum corrosive Severe current atmosphere loading capacity conditions For Current ratings. three core. sector shaped. and what is its impact on cable design? In-conduit systems might enable simpler. this issue of circulatory current in large screens of single core cables is a significant factor. life expectancy is reduced when the insulation is subjected to “over voltage”. Should cables be single core or 3-core? Single core cables can be cost-effective where impedance earthed systems are used which require relatively small screen sizes so that the cost for three core cables is economical. low-cost cable designs to be used. 62 OCI/PBTB/Rev-001/010909 . Which is best system. as it is impossible to take advantage of longer drum lengths with direct-buried systems. solid. Due to frequent presence of water in ducts. The details of various cable types can be checked in catalogues. etc. Cross-section of the conductor. there is an increasing interest in direct-burying using modern installation methods. Lead Sheathed. For 10/11 kV systems the trend is for 3-phase cables. Insulating material Paper Insulated. two core. XLPE insulated. At higher voltages and higher fault levels. extra high voltage cables. etc. etc. direct-buried or in-conduit. Single core cables are more easily water-blacked. in the form of surges and impulses. PVC insulated. three-and-a-half core. Rubber Sheathed. It is recommended that appropriate protection devices be installed and the nature and frequency of all such occurrences be monitored and recorded. multicore. etc. high voltage. Armoured or Unarmoured cables. Conductor material Copper conductor or Aluminium conductor. This is also true for large conductor sized cables. it becomes necessary to apply water barriers into the cable. The subject therefore of 3-core vs single core is an important issue. stranded. Aluminium Sheathed. What are the factors which reduce cable life? Voltage surges As with any electrical insulation. so that protective measures can be installed. Type of conductor. Rubber insulated. In many densely populated cities conduit systems are the only appropriate form of cabling. On the other hand. etc. Number of cores as single core. Sheathing material as PVC Sheathed.Frequently Asked Questions Cables can be divided into a large number of types based on a combination of classifications as follows: Voltage ratings low voltage. four core. The nature of frequency of all such occurrences should be monitored and recorded. The circuit protection system also needs to ensure adequate protection from excess current loading. Compatibility of design for cable and accessories Poor co-ordination of designs will result in incorrect/incompatible accessories.Excess operating temperatures The cables are designed for a maximum operating temperature with limited overload periods as defined in the relevant Standard. over tensioned. depth of cover. Microbiological effects from fungus and bacteria can induce increases in soil temperature thus affecting the temperature of the cable and causing unseen overloads. continuous monitoring of all key circuits is required. 63 OCI/PBTB/Rev-001/010909 . twisted. thermal movement and lack of compensation for seismic conditions. It is essential that correct methods of fixing and environmental assessment be undertaken to ensure the materials are not subjected to unforseen or unexpected stresses in service. excessive sidewall pressure induced. fixing methods. Changes in the environment. stresses induced by mechanical vibration. adjacent services and micro biological effects in the soil. Poor installation practices The lifetime of cables is dependent on the cable being installed correctly. bendings radii exceeded. To protect the investment and ensure the life of the cable. Increases in the thermal conductivity of the soil must be monitored and recorded. can increase operating temperatures and thus reduce cable life time. Adverse environmental conditions Environmental conditions can adversely affect the conditions for the cable. over compaction of backfill and other life threatening factors. Poor supervision/management and adverse installation conditions may cause the cable to be damaged. ................................................................................................................7645 Cubic metres to cubic yards......................1......................... .........................3937 Feet to metres ............................6093 Kilometres to miles .. ....................................................................746 Kilowatts to horse-power....................... 0........................................... .............................................................................................................................................................................Conversion Tables To Convert: Multiply by: Mils to millimetres (1..................... .................................1...............0.................00070307 kg/mm2 to lb/inch2 ..............................................................52 Square yards to square metres ..................................4. .......................................0.................................................1........................................................ Subtract 32 and multiply by 5/9 ˚C to ˚F ............................................................................................273...... ......................................496053 kg/km to lb/1000 yd.... .....................................................................................................................................................................................................................0936 Miles to kilometres....................000 mils=one inch)........... mils)...............................................24 Horse-power to kilowatts.............................................................................................................................................................6214 Square inches to circular mils (circ...........................................................................................205 Tons (2240 lbs) to kilogrammes.......0.....1.................................................................9144 Temperature: ˚F to ˚C ...............22 Horse-power to foot pounds per minute ......................... .....76 lb/1000 yd to kg/km...................................................................................................................................................................3...........0...................................................................3048 Metres to feet ..............1......................0610 Cubic yards to cubic metres ............................................ ..................................................... ................. ....................................................... .........................................8361 Square metres to square yards...............................................................00155 Circ.....................................240 Circular mils to square inches...............................................................0..............................0254 Inches to centimetres .......................................... Multiply by 9/5 and add 32 64 OCI/PBTB/Rev-001/010909 .....................................................................16.................................1.................................................................................................. ...............................76 ohm/1000 yd to ohm/km.....00050671 mm2 to circ...................................................... .................................................................... ...........................35 Grammes to ounces (avoirdupois)...........................................................0 Watts to foot pounds per minute .....................33000..................................................1973.............................................2....................................0353 Gallons (imp) to litres.0......0.............................................................. .................................................................................645.......... .......................................................................................................1016......................... mils to mm2 ..........................................................................................44...........................................................................................................................................................................34 lb/1000 yd to lb/mile.....................................................................................................................33 ohm/1000 yd to ohm/mile... ...................................................387 Cubic centimetres to cubic inches...............................................0........................... ..........308 Pounds (lbs) to kilogrammes....................2...... mils.................................1..........................................................................................................................0........16 Square millimetres to square inches.............7854 x 106 Square inches to square millimetres ............1........281 Yards to metres........................................................546 Litres to gallons (imp)....................................................02 Kilogrammes to tons (2240 lbs) ..............9144 Metres to yards...........................4536 Kilogrammes to pounds (lbs).............0.............................................. ............................................ .......................2....................................................................0........................00098 Ounces (avoirdupois) to grammes .....09361 ohm/km to ohm/1000 yd .................540 Centimetres to inches ........ ...0.............................................................. 0.......... 0......................1...............................................28......................01591 lb/inch2 to kg/mm2 ..................................................... 1422................0............................196 Cubic inches to cubic centimetres..............................................................0..........................0................................... 225 lbf 2.0254 volt/mil 7.0282 cub. inch 3.) Foot-Pounds 1. cm. Electric Field Strength 1 volt/mil 0. 0. 1 sq. cm 1 kg/sq cm.28084 feet 2.0936 ohm/km 1 ohm/km. yd.0936 ohm/km 1 ohm/km 1 ohm-metre 1 x 102 ohm-metre 0.836 13 sq.2046 lbf. Length 1 foot 3.6894 N/sq. Area 1 sq.3048 metre 1 metre Systeme.45 16 sq. metre 1 sq.507.3 volt/mm 1 volt/mm 1.9144 ohm/1000 yd 8.102 kgf. inch 0. International d’ ‘Units’ Unit (S.ft.54 ohm-cm 1 cps (cycle per second) 1 cub metre 0.46 lb/sq inch 6.836 13 sq.3048 metre 1 metre 0.Conversion Table Metric 0. 1 c.223 lb/sq. Pressure 1 lb/sq inch 14. 1 lbf. N/m2 39.0703 kg/sq. Resistivity 39. 1020 kg/sq cm 39. inch 14. 0. 1 Newton 9.0254 ohm-metre 1 Hz (hertz) 0. 4.m.3937 ohm-inch 1 ohm-inch OCI/PBTB/Rev-001/010909 9.19599 sq.37 ohm-inch 0.3 volt/mm 1 volt/mm 1. mm.80665 N/sq. metre 6.80665 N 4. 0. Force 0.m. metre 6.I. metre 1 sq. mm 1 cub metre 0.4536 kgf. mm. 100 ohm-cm 1 ohm-cm 2. 1 sq. Resistance 1 ohm/1000 yd 0.00155 sq. cm 9. 0.448 N 0. Volume 35. 5. yd 1. 1 kgf. mm.0282 cub.45 16 sq.29 cub ft. 1 sq. Frequency 1 cps (cycle per second) 65 . 000 001 = 10-6 0.01 = 10-2 0.1 = 10-1 0.001 = 10-3 0.000 000 000 000 000 001 = 10-18 66 OCI/PBTB/Rev-001/010909 .000 000 001 = 10-9 0.Basic Metric Units Magnitude (Powers of 10) Prefix tera giga mega kilo hecta deca – deci centi milli micro nano pico femto atto Symbol T G M k h da – d c m u n p f a Multiplication Factors 1 000 000 000 000 = 1012 1 000 000 000 = 109 1 000 000 = 106 1000 = 103 100 = 102 10 = 101 1 = 100 0.000 000 000 001 = 10-12 0.000 000 000 000 001 = 10-15 0. 7 380.0 177.367 10.53 10.15 26.4 608.0 550 600 650 700 750 800 900 1000 1100 1200 1250 1300 1400 1500 1600 1700 1800 1900 2000 mm2 2.7 557.AWG-kcmil vs metric mm2 AWG 14 12 10 9 8 7 6 5 4 3 2 1 1/0 2/0 3/0 4/0 kcmil 4.3 350.0 500.8 211.7 152.631 8.51 20.1 810.1 167.01 107.6 250.1 633.77 21.4 278.36 83.09 16.0 400.7 228.4 912.3 202.41 53.4 67 OCI/PBTB/Rev-001/010909 .82 26.7 861.261 6.0 405.3 16.74 52.24 33.4 456.0 253.7 709.38 13.09 41.0 329.4 658.43 85.31 5.62 42.6 133.62 66.11 6.69 105.67 33.0 506.1 962.0 450.55 13.4 760.7 304.7 1013.4 354.49 67.0 300.08 3.2 126. Guidance for AWG to Standard mm2 conversion AWG 30 28 26 24 22 21 20 18 17 16 14 12 10 8 6 4 2 1 2/0 3/0 4/0 300 MCM 350 MCM 500 MCM 600 MCM 750 MCM 1000 MCM mm2 0.05 0.25 0.50 0.0 1.14 0.5 4 6 10 16 25 35 50 70 95 120 150 185 240 300 400 500 68 OCI/PBTB/Rev-001/010909 .75 1.34 0.08 0.38 0.5 2.

Technical_Handbook - OMAN CABLES.pdf

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