TECHNICAL SPECIFICATIONS FOR AERIAL BUNCHED CABLES FOR OVERHEAD DISTRIBUTION

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Cordelia Reed
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1 TECHNICAL SPECIFICATIONS FOR AERIAL BUNCHED CABLES FOR OVERHEAD DISTRIBUTION 1 INTRODUCTION Aerial Bunched Cable (ABC) is a very novel concept for Over Head power distribution. When compared to the conventional bare conductor over head distribution system, ABC provides higher safety and reliability, lower power losses and ultimate system economy by reducing installation, maintenance and operative cost. This system is ideal for rural distribution and specially attractive for installation in difficult terrains such as hilly areas, forest areas, coastal areas etc. ABC is also considered to be the best choice for power distribution congested urban areas with narrow lanes and by-lanes. In developing urban complex, ABC is the better choice because of flexibility for rerouting as demanded by changes in urban development plan. 2 CONSTRUCTION OF ABC XLPE/HDPE insulated power conductors of Aluminum (Neutral conductor and, street lighting conductors if and when necessary) are laid together (twisted) around a high tensile stranded and galvanized steel (Aluminum Alloy may be used) insulated or bare messenger wire to form the Aerial Bunched Cable. This assembly is directly strung on to distribution pole/towers by means of standard hard wares available in the market but care shall be taken to render the messenger wire completely insulated from earthing at any point of distribution in case of HT ABC. The XLPE (Cross-linked Polyethylene) insulation is black in colour and is stabilized against deterioration caused by exposure to direct sunlight and ultraviolet radiation. XLPE is cross-linkable low density polyethylene which is made thermoset by special formation from base polymer of thermoplastic low density polyethylene. XLPE combines the best electrical properties of LDPE and superior thermo mechanical properties. 3 MATERIALS (i) Aluminium conductors conform to IS:8130 (Class-II) (ii) Stranded high tensile galvanized steel messenger wire conforms to IS:398 (Part-2). Alternatively Aluminium Alloy messenger wire conforms to IS:398 (Part-IV) (iii) XLPE and HDPE insulation of power conductors conform to IS: 7098 (Part I & II) and IS: 6474 respectively. Since, the tension -from the current carrying conductor is totally removed by introduction of messenger. wire the operating temperature of the conductor is 90 C as against 75 C of the bare conductor under tension thereby allowing ABC to carry current equivalent to that of bare conductor of the same size. 4 STRINGING No difficulty is envisaged during stringing of ABC in the conventional method but care shall be taken that insulated conductors do not get damaged during installation. Dragging the ABC on the ground is to be avoided. Tension to be applied during stringing shall be % of the breaking load of the messenger wires. This will allow line to have sag within specified limit of 1.5% of the span at the lowest ambient temperature. 5 JOINTING While mid-span jointing permissible for L T ABC system by conventional technique, our recommendation will be to draw the line in such a way as to bring the joints at the supports. Mid-span jointing is not at all recommended in the case of HT lines our recommendation is for outdoor type HV terminations only. Under unavoidable circumstances, line tapping at the support points may be allowed through suitably designed clamp connectors/pg clamps. The semi-conducting screen continuity shall be maintained at all joints as far as possible to avoid fluctuations during system disturbances. The 3-phase screens may be shorted and earthed through suitable non-linear surge arrestor. Attempting to make a tap off from power conductors in the region where catenary is under tension is not recommended. 6 RELIABILITY, SAFETY AND FLEXIBILITY: ABC Cables are highly reliable and insulation has been developed to withstand heat, cold and intense sunlight. Disturbance and faults occur five to ten times more often in open wire lines than in ABC lines. There is no risk in touching the live cable and the insulation reduces the number of short circuits and over-voltages in overhead cables during thunder-stones. Few hardware accessories are needed as each one can be used with many different sizes of cable. This makes installation and storage easier. Streets can easily be get lit at little extra cost by using the ABC cables that have an extra conductor for lighting. The cable can be supplied with one or two insulated conductors for street lighting. The hardware and accessories for AB cables are made by various reputed manufacturer and is easily available in India. They are similar to the standard hardware available for Bare conductor overhead distribution lines.

2 7 APPROVAL & CERTIFICATION (i) BIS License for 1S for 1l00V Wires & Cables. (ii) BIS License for IS (iii) BIS License for I_ 7098 PART 1 & II (iv) BIS License for Overhead Aluminium Conductor (18-398) and Copper Conductor (1S-282) and for other Conductors. (v) Quality System Certification upgradation from ISO to' ISO 9001 by Underwriters Laboratories, in final stage. (vi) Safety Certification for various conductors as per BASEC are under finalization. TECHNICAL PARTICULARS LT Aerial Bunched Cable 1100 Volts (4 crore) Reference standard: Generally to IS:7098(1)88

3 QUALITY SETUP Conductors are generally the only means to transport current or signals with required safety norms. Therefore the material of its construction, purity and other important aspects of metallurgy are the critical factors to source the wire rods. We have latest 3-D profile die checking and refurbishment system. The sourcing of wire drawing, lubricant is from company like Houghton Italy and intensive inspection testing Conductor to ensure quality. QA IN PLANNING Customer requirements, alongwith the orders are taken into quality planning with due care for designing, manufacturing, testing and performance aspects QA IN RAW MATERIALS The raw materials are procured from the best sources from the domestic and global market These sources are selected on the based on the company's stringent quality vendor evaluation/ continuous assessment and testing. QA ONLINE The company has online computerised control system on all its critical processes and a team of on line testing engineers to ensure the consistency in quality TESTING Each consignment of conductor & wires is exhaustively tested before dispatch clearance, by highly qualified, Experienced and dedicated testing team. The testing setup is broadly classified as follows 1) RM. Testing Labs. 2) Routine Testing for Conductor, LT wires & Cables 3) Type Testing Labs include FR/FS/FRLS testing All the laboratories are equipped with the modern testing Instruments. All the instruments are under strict Calibration and environment control.

4 TECHNICAL PARTICULARS LT Aerial Bunched Cable 1100 Volts (3 1/2 crore) Reference standard: Generally to IS:71098(1)88

5 FINISHED AERIAL BUNCHED CABLE TESTING Prior to despatch cable is subjected to rigorous testing. Test procedures followed at our works are according to various national & International specifications and are covered in this paper. Following tests are performed on Aerial Bunched Cables: 1. Test on Phase/Street lighting conductor TESTS METHOD OF TESTING a) Tensile test IS: pt -2 b) Wrapping test IS: pt -3 c) Conductor Resistant Test IS: pt - 5 d) Test for thickness of insulation IS: pt -6 e) Physical test for polyethylene insulation (i) Tensile strength & Elong Test IS: pt -7 (ii) Melt flow index IS: pt -23 (iii) Vicat softening Point IS: pt - 22 (iv) Carbon Black Content & IS: pt - 32 dispersion (v) Colour factness IS: pt - 18 (vi) Environmental stress cracking IS: pt - 29 (vii) Bleeding & Blooming IS: pt -19 (viii) Volume Resistivity test IS: pt -43 (f) High Voltage test including water IS : 1596 immersion test. 2. Test for messenger conductor a) Breaking load test IS:398 (pt - IV) b) Elongation test IS: 398 ( pt - IV) c) Resistance test IS: 398 (pt - IV) 3. Dimensional test as per the parameters specified in the technical particulars 4. Bending test on completed cable shall also as performed. The diameter of mandrel shall be 10 (Dd) Where D = Overall diameter of the cable d = Dia over conductor

6 TECHNICAL PARTICULARS LT Aerial Bunched Cable 1100 Volts (4 crore) Reference standard: Generally to IS: S.No Description 3 x 1 x 3 x 1 x 3 x 35 1 x 3 x 50 1 x Power/ Neutral Core : Conductors a) Nom.cross sectional area (i) Power cores (mm2) (ii) Neutral conductor (mm2) b) Max D C resistance conductor at 20 c (i) Phase conductor (Ohm/Km) (ii) Neutral Conductor (Ohm/Km) c) Approx. diameter of Conductor (Compacted) (i) Phase conductor (mm) (ii) Neutral conductor (mm) Insulation: Minimum thickness (i) Phase conductor (mm) Messenger Wire (Bare): (i) Nom. Cross sectional area (Sq mm) 35 (ii) Approx Tensile Strength (KN) Current ratings: Continuous current carrying capacity of cable in Air at Ambient temp. 40 c (AMP) Approx weight (Kg/Km) Number of cores: (i) Power cores (No.) : 3 (ii) Neutral Messenger Core (No.) : 1 6 Derating factor: Derating factors for variation In air Temp Air Temp ( C) Rating factor (i) Identification of Power core: (ii)laying: 8 Details of the Power/Neutral core: (i) Conductor (a)material (b)flexibility class as per IS:8130/84 (c)form of conductor (ii) Insulation (a) Material (b) Colour of Insulation By providing ridges on the insulation Three power cores and one neutral core shall be suitably twisted around bare AAAC Messenger. Aluminium to IS: 8130/84 Class 2 Compacted circular High Density Polyethylene to IS: Black 9 Details of the Messenger wire (Bare) (a) Material (b) Form of conductor All alloy aluminium Conductor to IS:398 (IV) Stranded compacted circular

7 TECHNICAL PARTICULARS LT Aerial Bunched Cable 1100 Volts (5 Crore) with Street Lighting Conductor - Reference Standard: Generally to IS: S. No Description 3 x 1 x 1 x 3 x x 1 x 3 x 35 1 x 1 x 3 x 50 1 x 1 x 35 3 x 70 1 x 1 x 50 3 x 95 1 x 1 x 70 3 x x 1 x Power/ Neutral Core : Conductors a) Nom.cross sectional area (i) Phase Conductor (mm2) (ii) Street Lighting conductor (mm2) b) Max D C resistance conductor at 20 c (i) Phase conductors (Ohm/Km) (ii) Street Lighting (Ohm/Km) c) Approx. diameter of Conductor (i) Phase conductor (m m) (ii) Street Lighting conductor (mm) Insulation: Minimum thickness (i) Phase conductor (mm) (ii) Street Lighting Conductor (mm) Messenger Wire (Bare): (i) Nom. Cross sectional area (Sq mm) (ii) Approx breaking load (KN) Current ratings: Continuous current carrying capacity of cable in Air at Ambient temp. 40 c (AMP) Approx weight (Kg/Km) Number of cores: (i) Power cores (No.) : 3 (ii) Neutral Core (No.) : 1 (iii) Bare Messenger (No.) : 1 6 Derating factor: Derating factors for variation In air Temp Air Temp ( C) Rating factor (i) Identification of Power core: (ii) Laying: 8 Details of the Power/Neutral core: (i) Conductor (a) Material (b) Flexibility class as per IS:8130/84 (c) Form of conductor (ii) Insulation (a) Material (b) Colour of Insulation By providing ridges on the insulation Three power cores and one neutral core shall be suitably twisted around bare AAAC Messenger. Aluminium to IS: 8130/84 Class 2 Compacted circular High Density Polyehylene to IS: Black 9 Details of the Messenger wire (Bare) (c) Material (ii) Form of conductor All alloy aluminium Conductor to IS:398 (IV) Stranded compacted circular

8 TECHNICAL SPECIFICATION FOR LV AERIAL BUNCHED CABLES (I) SCOPE This specification covers design, engineering, manufacture, assembly, stage testing, inspection and testing before supply and delivery at site of HIGH DENSITY POLYETHYLENE Insulated (HDPE) Aluminum Cables twisted over central bare aluminum messenger' wire. The sizes are lx sq.mm and 2x Sqmm. (II) STANDARDS The materials shall conform in all respects to the relevant Indian Standard Specifications with latest amendments thereto. Indian Title International & Standard Internationally ecognised standard IS /1984 Aluminium conductors for Insulated electric cables IS /1984 Polyethylene Insulation for cables for voltage upto and including 1000 V IS-398/Part-IV/ All Aluminium Alloy IEC - 228/ Conductors (AAAC) for overhead Transmission purposes Conductors of Insulated Cables IS 10418/1982 Drums for electric cables IS - 656/1988 Specification for logs for BS148/ASTMD plywood 1275, D1533, D 1934, IEC PUB Material conforming to other internationally accepted standards, which ensure equal or higher quality than the standards mentioned above would also be acceptable. In case the Bidders who wish to offer material conforming to the other standards, salient points of difference between the standards adopted and the specific standards shall be clearly brought out in relevant schedule. Four copies of such standards with authentic English Translations shall be furnished along With the offer. (III) TECHNICAL REQUIREMENTS a. General: The insulated phase conductor shall be twisted round bare aluminium alloy messenger wire, which shall take all the mechanical stress. The messenger shall also serve as the earth-cumneutral. The typical arrangement of the phase conductors and messenger wire shall be as per relevant standards. The typical arrangements of cables straight run, Angle and Dead end shall be (IV) as per relevant standards. PHASE CONDUCTOR The sq.mm. phase conductor shall be of aluminium solid round; outer diameter shall be within the limits. The phase conductor shall be insulated with black weather resistant high-density polyethylene (HDPE) suitable to 1100 V insulation. The insulated conductors shall generally conform to the relevant standards. Conductors: The properties of the aluminium wires before stranding shall be: Tensile strength not less than 90 N/Sq.mm. Resistivity at 20 Deg. C not exceeding ohm / Sq.mm / m (V) INSULATION a. Material: The insulation shall be black weatherresistant special high-density polyethylene. b. Messenger (Neutral conductor): The messenger shall be an All Aluminium Alloy Conductor composed of 7 wires each of 2.34 mm. Dia. drawn from rod, which is manufactured in a continuous casting and rolling procedure. The properties for the individual wires before stranding shall be: Tensile strength not less than 294 N / sq.mm. Elongation at 0 mm gauge length not less than 4%. Density at 20 Deg. C not exceeding ohm /sq.mm./m. Density at 20 De"g. C 2.7 Kg./Cubic-dm No joints are allowed in the messenger except those made on the base rod or wire before final drawing within the standard length of 2 km. The messenger shall be round, stranded and compacted to have smooth round surface. The messenger takes all the mechanical stress and also serves as a neutral conductor. Neutral conductor over all dia (max.)6.5 mm DC resistance at 20 ego C(Max) 1.38 ohm / km Minimum breaking load 7.4 kn. c. Design: The cable consists of one black weather resistant special high-density polyethylene (HDPE) insulated Aluminium phase conductor, stranded around a bare All Aluminium Alloy messenger, which is also the neutral conductor. The construction data

9 is specified below: No. of cross sectional area of conductor (sq.mm) Phase Conductor Messenger Complete cable No and Diameter Insulation Overa Diameter of Tensile Overall Total cross of un - thickness ll dia uninsulated strength diameter mass sectional area insulated cond uctor (mm) of condu conductor Max (mm) (approx) Min (Kg) (approx) (mm) (approx) (Kg/Km) (sq.mm) Max (mm) ctor (mm) 1 x 1 x d. The resistance of the phase conductor and the messenger are determined with direct current the same are corrected to 20 Deg. C using the formula and co-efficients given in clause 5 of standard IEC228. The values obtained shall not exceed the resistance, given below: Nominal Cross sectional area of conductor (sq.mm) No. of strands DC Resistance at 20 C Ohm/Km (Max) Insulation thickness average in (mm) Phase Neutral conductor conductor Aluminium Aluminium alloy Bare Note: The average value of thickness of the insulation shall not be less than the specified average value' The thickness at any place may be less than the specified average value, provided that the difference not exceed 0.1 mm. For thickness of insulation six measurements are made readily on a piece of insulation as far as possible equally spaced around the circumference but not on the ridges. e. Polyethylene Insulation: The polyethylene insulation shall generally conform to relevant Standards. The.following properties shall be guaranteed by the supplier. For methods of testing IS-I086 (relevant parts) may be referred. Density of HDPE (ST4) 0.95 to 0.96 g/cu.cm Melt flow index max 3.0 Tensile strength Not less than 10 N/sq.mm Percentage elongation Not less than 300 Carbon black contents Between 2 and 3% Vicat softening point Not less than 85 Deg. C At 70 Deg 1 x 1013 Ohm cm (min) Environmental stress cracking No cracks shall be visible to the naked eye (VI) TESTING a. Type Tests: The material offered shall be fully type tested by the Bidder or his collaborator as per the relevant standards. The bidder shall furnish four sets of type test reports along with bid. The bids received without type test reports shall be treated as non-responsive. Tests for phase conductor Tensile test (IS:8130) Wrapping test (IS:8130) Conductor resistance test Test for thickness of insulation Tensile strength and elongation at break of insulation Physical tests for polyethylene insulation Ageing in air oven Shrinkage test Hot deformation Loss of mass in air oven Heat shock test Thermal stability Test for bleeding and blooming of pigment (IS:6474) Insulation resistance test High voltage test including water immersion test (IS: 1596) High voltage test at room temperature Flammability test b. Test for messenger Breaking load test (to be made on the finished conductors (IS 398/Part IV) Elongation test (IS-398/part IV). Resistance test (IS-398/part-IV) c. Acceptance and Routine Tests: All the acceptance and routine tests shall be conducted as per the relevant standards in the presence of purchaser's representative. The values shall conform to guaranteed values. Immediately after finalization of the Programme of acceptance/routine testing, the manufacturer shall give 15 days advance intimation to the purchaser, to enable him to depute his representative for witnessing the tests. d. Bending test on the complete cable: The test shall be performed on a sample of complete: cable. The sample shall be bent around a test mandrel at room temperature for at least one complete turn. It

10 shall then be unwound and the process shall be repeated after turning the sample around its axis 180 Deg. The cycle of these operations shall then be repeated twice more. The diameter of the mandrel shall be 10 (Dd), where D-= Actual diameter of the cable (i.e. minimum circumscribing circle diameter in mm) d= actual diameter of the conductor in mm. No cracks visible to the naked eye should take place. (VII) PACKING & FORWARDING: a. The AB Cable shall be wound on non-returnable wooden drums conforming to IS-I 0418/ 1982 with latest amendments thereof. The ends of the cable shall be sealed by means of non-hygroscopic sealing material. The drum shall be marked with the following. Manufacturers name Trademark, if any Drum number or identification number Size of conductors Size of messenger Voltage grade Number and lengths of pieces of cable in each drum Gross mass including packing ISI mark if any Direction of rotation of the drum by marking an arrow b. The drums shall be of such construction as to assure delivery of cable in the field free from displacement and damage and should be able to withstand all stresses due to handling and the stringing operation so that cable surface is not dented, scratched or damaged in any way during transport and erection. The cable shall be properly lagged on the drums. c. The cable drum should be suitable for wheel mounting d. The mass of finished cable in a drum (without mass of drum) of various designation shall not exceed by more than 10% of the following values. Designation lxi6 Sq. mm 2xl6 Sq. mm Gross mass 800 Kg 1000 Kg e. The minimum length of each cable shall be 2km. While longer lengths shall be acceptable, shorterlengths not less than 1 kilometers shall be acceptable to the extent of 10% of the ordered quantity only. (VIII) MARKING OF CABLES: - All the cable shall have the following marking embossed on the insulated phase conductor for identification DHBVNL in intervals of not more than 1 meter. a. The packing shall be done as per the manufacturers standard practice. However, he should ensure the packing is such that the material should not get damaged during transit by Rai1/ Road. b. The marking on each package shall be as per the relevant IS (IX) GUARANTEED TECHNICAL PARTICULARS The Contractor shall furnish the guaranteed technical particulars and submit the same along with his tender.

TECHNICAL SPECIFICATION A.B. CABLE

TECHNICAL SPECIFICATION A.B. CABLE 1.0 NATURE OF WORK The work covered by this Specification is for L.T lines in A.B cable as specified herein and in the attached Schedules. The overhead distribution lines