CABLE AND LAYING
-B. Prasad
Chartered Engineer
amieclub@gmail.com
Cable cut view
TYPE OF CABLE BASEDON CONSTRUCTION
 Coaxial cable
 Mineral-insulated copper-clad cable
 Twinax cable
 Flexible cables
...
Cable for electrical
 PVC cable upto 3.3KV
 XLPE cable upto 33KV
 LT and HT ABC cable
 Instrumentation cable
 Concent...
Elastomer
 Trailing cable
 Locomotive cables
 Ship wiring cable
 Wind mill cable/solar cable
 Welding cable
 Mining ...
Telecom
 PIJF cable
 5-2400 pair
 Indoor telephone cable
 QUAD/PCM cable
 Optical fibre cable
 Armoured/duct/aerial
...
Fiber-Optic Cable
Advantages:
 It operate at high speeds
 It has a large carrying capacity
 The signals can be transmit...
Construction of cable
Construction of XLPE
Construction of EHV XLPE single core
XLPE has replaced conventional cable
Insulating material
 PVC (Polyvinyl
Chloride)
 PE (Polyethylene)
 XLPE (Cross-Linked
Polyethylene)
 EPR (Ethylene
Prop...
Junction bus
1. Electrical Junction Boxes
2. Wiring Junction Boxes
3. Electric Junction Boxes
4. Plastic Junction Boxes
5....
Cable lug
 Material:
copper
&
aluminium
 Conductivity
:
 Copper
99.7%
iacs
 Aluminium
61.2%
Cable lug ---contd
Cable manufacturers
 Name of manufacturer Brand
1. N.C cable industries National
2. Evershine Electric Works ECKO
3. Elec...
Historical progress of cable technology
Historical voltage development in country
Indian and international
standard
Reduction in insulation thickness
Metallic sheath
Lead sheath construction
Electrical Resistivity
Material Resistivity (µΩ-
cm@20 deg.C)
Copper 1.724
Aluminium
2.826
Steel 13.8
Lead 21.4
Density of material
Importance of cable installation
 A poor installation creates unreliable service
 other agency my damage the cable.
 Te...
Location of cabling
 Laying direct in ground
 In pipes,
 Closed or Open ducts,
 Cable trays and
 On surface of wall
Step of cable installation
 Route survey
 Permission
 Trial pits
 Pipe laying
 Material shifting, drum placement
 Tr...
Route survey
 Type of surface like footpath, PCC, RCC, soil
type
 Hazardous like tree roots, pillars, sever line,
drain,...
Trial pit
 Along the
proposed cable
root.
 Trial pit at the
interval of 15-20
meter
Permission
Before starting the excavation permission to be
taken
 Railways
 Traffic police and defence
 Forrest departm...
Digging
 To display “Men
at work”
 Don't damage
the other cable
 Least use of
pickaxe and
chisel
 Correct Depth
depend...
Depth of cable
 LT cable (1.1KV) 0.75 m
 HT cable (11KV) 0.90 m
 HT cable (33KV) 1.20 m
 Sand - covered with 150 mm
 ...
Minimum bending radius
Voltage
rating
PILC cable PVC & XLPE cable
KV Single core Multicore Single core Multicore
Upto 1.1 ...
Pipe laying
 if cable crossing the road, gate, railway track,
water line
 Type of pipe: GI, cemented, HDPE pipe
 Ends t...
Bedding
 Before and after cable laying and jointing work
is over a bedding of sieved earth or river bed
sand of 100 mm de...
Cable under bed/on support
CABLE LAYING IN TRAY
Cable laying on rack
Tagging on cable
Use barricading tape
Cable handling
Cable handling tools
 Jack
 Roller
 Drum trailer
 Crimping
tool
Cable installation record
 Type of cable and its size
 Voltage level
 Cable no, drum no.
 Date
 Rout map, location of...
Testing of cable installation
 Insulation resistance test
 High voltage test
 Continuity test
Value
 IR value : minimu...
Cable testing
Type test
Routine test
Pre-commissioning test
A) for new cable after installation
B) After repairing the ...
Insulation resistance test
Before jointing and after
jointingS
no.
Voltage Test voltage
New installation Old installation...
High voltage test value
Sr. Voltage level
of the cable
under test
Test voltage Observed leakage
current (maximum)
New
inst...
Cable testing at manufacturer’s works
 a) Tensile Test (For Aluminium Conductor)
 b) Wrapping Test (For Aluminium Conduc...
Cable short circuit
 ISC = kA /√t
 K= Constant
 Al -- 0.094 (XLPE)
 Cu -- 0.14382 (XLPE)
 A - Cross Section Area (mm ...
Earthing
 Metal screen
(if any) and
armour of
cable to be
earthed.
 All metal
pipes in which
cables have
been installed
...
Corrosion Types Encountered With Power Cables
 Anodic Corrosion (Stray
DC Currents)
 Cathodic Corrosion
 Galvanic Corro...
Voltage drop calculation
 For DC and single phase AC two wire
systems
 Voltage drop = (2xIxLxRxt)/1000
 Where I = curre...
Voltage drop ----contd
 For three phase AC systems
 Voltage drop = (1.732xIxLxRxt)/1000
 Note: formula is applied when ...
Resistance
Voltage drop value in%
Failure in cable
 Internal and surface discharge may result failure of
the insulation.
 Proper drying, due to low /bad q...
Root marker
 Aluminium
 Cast Iron
Material with
Standard or
Custom design
 Fibreglass
Reinforced
Plastic [FRP]
Cable tape
 Size:
 Length: 5Y, 5m,
10Y, 10m, 20Y,
20m.
 Width: 12mm,
15mm. 17mm,
18mm, 19mm,
25mm, 48mm,
50mm.
Cable gland
 Type of Cable
 Gland Size
 Entry Type/Thread
Specification of
application
 Ingress Protection
required.
...
Parts of gland
Type of Gland
 A1 and A2 Type Cable
Gland
 BW Type Cable Gland
 CW Type Cable Gland
 Single Compression
Cable Gland
 ...
Cable ties material
 Nylon 66
 Nylon 66 UV Stabilized
 Nylon 66 Heat Stabilized
 Polypropylene
 Tefzel
DIN rail and terminal block
De-rating factor
 Thermal insulation factors
 Ambient temperature
 Group factor
 Depth of laying
 Thermal resistivity...
Busbar
Material :
 Aluminium
 Copper
Technical specification
 Rating Current:3200Amp.
 System:415Vac, TPN,
50Hz.
 Fau...
Cable entry
 Indoor application:Top and bottom both
 Outdoor application: Only bottom
Conduit Fittings & Accessories
 Construction:
Galvanized steel,
helically wound, Flexible
Conduit System.
 Temp: -50 C t...
ACT FAST AND INITIATE
FIRST
 बड़ा    सोचो
        तेजी से सोचो व
    सबसे पहले सोचो
 िवचारो     पर िकसी का
      एकािध...
THANK
YOU
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Cable construction and laying

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Cable and laying

  1. 1. CABLE AND LAYING -B. Prasad Chartered Engineer amieclub@gmail.com
  2. 2. Cable cut view
  3. 3. TYPE OF CABLE BASEDON CONSTRUCTION  Coaxial cable  Mineral-insulated copper-clad cable  Twinax cable  Flexible cables  Non-metallic sheathed cable (or nonmetallic building wire, NM, NM- B)[1]  Metallic sheathed cable (or armored cable, AC, or BX)[1]  Multicore cable (consist of more than one wire and is covered by cable jacket)  Shielded cable  Single cable (from time to time this name is used for wire)  Twisted pair  Twisting cable
  4. 4. Cable for electrical  PVC cable upto 3.3KV  XLPE cable upto 33KV  LT and HT ABC cable  Instrumentation cable  Concentric core cable  Flexible cable & wire  FR/FRLS/LSOH cable  Fire survival cable  Under water cable
  5. 5. Elastomer  Trailing cable  Locomotive cables  Ship wiring cable  Wind mill cable/solar cable  Welding cable  Mining cable  LFH cable and wire  Fire survival cable  EPR, Silicon, EVA cables
  6. 6. Telecom  PIJF cable  5-2400 pair  Indoor telephone cable  QUAD/PCM cable  Optical fibre cable  Armoured/duct/aerial  Torpedo cable  TOW cable  Composite cable
  7. 7. Fiber-Optic Cable Advantages:  It operate at high speeds  It has a large carrying capacity  The signals can be transmitted further without being strengthened.  It is immune to interference caused by electromagnetic noise such as radios, motors, or other nearby cables.  It is cheaper to maintain.  You do not have to worry about grounding1 the cable. Disadvantages:  The cable is more expensive than copper cables.  It is difficult to install.
  8. 8. Construction of cable
  9. 9. Construction of XLPE
  10. 10. Construction of EHV XLPE single core
  11. 11. XLPE has replaced conventional cable
  12. 12. Insulating material  PVC (Polyvinyl Chloride)  PE (Polyethylene)  XLPE (Cross-Linked Polyethylene)  EPR (Ethylene Propylene Rubber)  LSF (Low smoke and fume)  Polytetrafluoroethylene (PTFE)  Thermoplastic Rubber (TPR)  Neoprene (Polychloroprene)  Styrene Butadiene Rubber (SBR)  Silicone  Rubber  Chlorosulfonated Polyethylene (CSPE)
  13. 13. Junction bus 1. Electrical Junction Boxes 2. Wiring Junction Boxes 3. Electric Junction Boxes 4. Plastic Junction Boxes 5. Cable Junction Boxes 6. Plastic Electrical Junction Boxes 7. Weather proof junction boxes 8. Flameproof junction boxes
  14. 14. Cable lug  Material: copper & aluminium  Conductivity :  Copper 99.7% iacs  Aluminium 61.2%
  15. 15. Cable lug ---contd
  16. 16. Cable manufacturers  Name of manufacturer Brand 1. N.C cable industries National 2. Evershine Electric Works ECKO 3. Electric Cable Industries ECI 4. Paragon Cable Company paragon 5. Surya Power Limited ALCAB 6. National insulated cable co. NICCO 7. Indian cable company INCAB 8. Aluminium industries limited ALIND 9. R.K Electrical KALINGA 10. Polycab Industries POLYCAB 11. Plaza Cable PLAZA 12. Empire Cable Industries EMPIRE 13. Hovels cable HAVELL 14. Cable corporation of India CCI 15. Kei Industries Limited KEI
  17. 17. Historical progress of cable technology
  18. 18. Historical voltage development in country
  19. 19. Indian and international standard
  20. 20. Reduction in insulation thickness
  21. 21. Metallic sheath
  22. 22. Lead sheath construction
  23. 23. Electrical Resistivity Material Resistivity (µΩ- cm@20 deg.C) Copper 1.724 Aluminium 2.826 Steel 13.8 Lead 21.4
  24. 24. Density of material
  25. 25. Importance of cable installation  A poor installation creates unreliable service  other agency my damage the cable.  Telephone cable, communication cable, water line, gas pipe line may get affected
  26. 26. Location of cabling  Laying direct in ground  In pipes,  Closed or Open ducts,  Cable trays and  On surface of wall
  27. 27. Step of cable installation  Route survey  Permission  Trial pits  Pipe laying  Material shifting, drum placement  Trenching cable laying  Bedding and tiling  Backfilling  Cable installation record  tagging
  28. 28. Route survey  Type of surface like footpath, PCC, RCC, soil type  Hazardous like tree roots, pillars, sever line, drain, bus stop, water pipe, gas pipe  Cable root passing from private property  Cable root away from parallel running gas, water pipe, communication cable etc  Road crossing, over bridge, drain crossing
  29. 29. Trial pit  Along the proposed cable root.  Trial pit at the interval of 15-20 meter
  30. 30. Permission Before starting the excavation permission to be taken  Railways  Traffic police and defence  Forrest department  Communication and gas authority  Other service department if any
  31. 31. Digging  To display “Men at work”  Don't damage the other cable  Least use of pickaxe and chisel  Correct Depth depending upon voltage grade
  32. 32. Depth of cable  LT cable (1.1KV) 0.75 m  HT cable (11KV) 0.90 m  HT cable (33KV) 1.20 m  Sand - covered with 150 mm  Width of the trench - 350 mm minimum  Loop –approximate -3 meter each side
  33. 33. Minimum bending radius Voltage rating PILC cable PVC & XLPE cable KV Single core Multicore Single core Multicore Upto 1.1 20D 15D 15D 12D 1.1 to 11 20D 15D 15D 15D Above 11 25D 20D 20D 15D
  34. 34. Pipe laying  if cable crossing the road, gate, railway track, water line  Type of pipe: GI, cemented, HDPE pipe  Ends to be sealed to avoid choking, clogging.  Standard depth of pipe: 1m across the road, 1.8 m across railway track.  Standard size of pipe: 1.5 times of cable  Spare pipe: for future expansion , Ends to be sealed
  35. 35. Bedding  Before and after cable laying and jointing work is over a bedding of sieved earth or river bed sand of 100 mm depth both below and above the cable.  Keep distance between two cable in single trench.  Avoid zig-zag
  36. 36. Cable under bed/on support
  37. 37. CABLE LAYING IN TRAY
  38. 38. Cable laying on rack
  39. 39. Tagging on cable
  40. 40. Use barricading tape
  41. 41. Cable handling
  42. 42. Cable handling tools  Jack  Roller  Drum trailer  Crimping tool
  43. 43. Cable installation record  Type of cable and its size  Voltage level  Cable no, drum no.  Date  Rout map, location of cable joint  Installation test record like IR value, HV test if any
  44. 44. Testing of cable installation  Insulation resistance test  High voltage test  Continuity test Value  IR value : minimum 1M-ohm/KV  HV test value : minimum 1KV/KV +1 for 5 minutes
  45. 45. Cable testing Type test Routine test Pre-commissioning test A) for new cable after installation B) After repairing the breakdown
  46. 46. Insulation resistance test Before jointing and after jointingS no. Voltage Test voltage New installation Old installation Recorded IR value 1 upto1.1KV 500 V dc for 1 min. 1.0KV dc for 1 min. 50MΩ 2 11KV 1.0KV dc for 1 min. 2.5KV dc for 1 min 200MΩ 3 33KV 2.5KV dc for 1 min. 5.0 KV dc for 1 min. 500MΩ 4 66KV 5.0 KV dc for 1 min. 5.0 KV dc for 1 min. 500MΩ
  47. 47. High voltage test value Sr. Voltage level of the cable under test Test voltage Observed leakage current (maximum) New installation Old installation New installation Old installation 1 upto1.1KV 3KV 660V 0.5mA 2mA 2 11KV 18KV 6.5KV 0.5mA 2mA 3 33KV 60KV 19.5KV 0.5mA 2mA 4 66KV 115KV 38KV 0.5mA 2mA
  48. 48. Cable testing at manufacturer’s works  a) Tensile Test (For Aluminium Conductor)  b) Wrapping Test (For Aluminium Conductor)  c) Annealing Test (For Copper Conductor)  d) Conductor Resistance Test  e) Test for thickness of Insulation & Sheath  f) High Voltage Test  g) Insulation Resistance Test  h) Tensile Strength & Elongation at break test for  Insulation and Sheath  I) Hot Set Test - (for XLPE Insulation only)  j) Partial Discharge test (for H.T. Screened cable)
  49. 49. Cable short circuit  ISC = kA /√t  K= Constant  Al -- 0.094 (XLPE)  Cu -- 0.14382 (XLPE)  A - Cross Section Area (mm 2 )  T- Time in seconds
  50. 50. Earthing  Metal screen (if any) and armour of cable to be earthed.  All metal pipes in which cables have been installed need to be earthed.
  51. 51. Corrosion Types Encountered With Power Cables  Anodic Corrosion (Stray DC Currents)  Cathodic Corrosion  Galvanic Corrosion  Chemical Corrosion  AC Corrosion  Local Cell Corrosion  Other Forms of Corrosion
  52. 52. Voltage drop calculation  For DC and single phase AC two wire systems  Voltage drop = (2xIxLxRxt)/1000  Where I = current in ampere  L = length of cable in meter (one conductor only)  R = resistance of one conductor from table  t = temperature correction factor
  53. 53. Voltage drop ----contd  For three phase AC systems  Voltage drop = (1.732xIxLxRxt)/1000  Note: formula is applied when power factor is unity. Power factor to be considered in load and reactance to be considered. Note:  formula is applied when power factor is unity. Power factor to be considered in load and reactance to be considered.
  54. 54. Resistance
  55. 55. Voltage drop value in%
  56. 56. Failure in cable  Internal and surface discharge may result failure of the insulation.  Proper drying, due to low /bad quality of fluid.  Ingress of moisture and degradation of insulation.  Crack in the sheath, due to abnormal temperature, electrical stress, mechanical tension.  Voids due to partial discharge.  Overheating, deformation, ionization etc.  NB: permitted size of voids in cable to be 22-25 micron.
  57. 57. Root marker  Aluminium  Cast Iron Material with Standard or Custom design  Fibreglass Reinforced Plastic [FRP]
  58. 58. Cable tape  Size:  Length: 5Y, 5m, 10Y, 10m, 20Y, 20m.  Width: 12mm, 15mm. 17mm, 18mm, 19mm, 25mm, 48mm, 50mm.
  59. 59. Cable gland  Type of Cable  Gland Size  Entry Type/Thread Specification of application  Ingress Protection required.  Material
  60. 60. Parts of gland
  61. 61. Type of Gland  A1 and A2 Type Cable Gland  BW Type Cable Gland  CW Type Cable Gland  Single Compression Cable Gland  Double Compression Cable Gland  Flameproof Cable Glands  E1W Type Cable Gland  Flange Type Cable Gland  PG Type Cable Gland  Marine Type Cable Gland  Metric Threaded Cable Gland  Weather Proof Cable Glands
  62. 62. Cable ties material  Nylon 66  Nylon 66 UV Stabilized  Nylon 66 Heat Stabilized  Polypropylene  Tefzel
  63. 63. DIN rail and terminal block
  64. 64. De-rating factor  Thermal insulation factors  Ambient temperature  Group factor  Depth of laying  Thermal resistivity Depth of laying (cm) 75 90 105 120 150 180 Cable size < 25 sqmm 1 0.99 0.98 0.97 0.96 0.95 Cable size < 300 sqmm 1 0.98 0.97 0.96 0.94 0.93 Cable size ≥ 300 sqmm 1 0.97 0.96 0.95 0.92 0.91
  65. 65. Busbar Material :  Aluminium  Copper Technical specification  Rating Current:3200Amp.  System:415Vac, TPN, 50Hz.  Fault Level:50KA. For 1 Sec.  Operation Temp:40° C rise over 45 ° C ambient
  66. 66. Cable entry  Indoor application:Top and bottom both  Outdoor application: Only bottom
  67. 67. Conduit Fittings & Accessories  Construction: Galvanized steel, helically wound, Flexible Conduit System.  Temp: -50 C to +200 C  Features: Highly Flexible and mechanical strength  IP: IP4
  68. 68. ACT FAST AND INITIATE FIRST  बड़ा    सोचो         तेजी से सोचो व     सबसे पहले सोचो  िवचारो     पर िकसी का       एकािधकार नही होता.   ----  धीरभाई अमबानी
  69. 69. THANK YOU
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