This document provides information on various types of cables based on their construction and use. It discusses cable types for electrical, telecom, fiber optic and other applications. It also describes the construction of different cable types like XLPE and covers aspects of cable installation like laying, jointing, testing and maintenance. Common cable accessories used are also explained.
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. 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
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.
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. Location of cabling
Laying direct in ground
In pipes,
Closed or Open ducts,
Cable trays and
On surface of wall
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. 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. Trial pit
Along the
proposed cable
root.
Trial pit at the
interval of 15-20
meter
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. 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. 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. 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. 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. 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
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. 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
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. 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. 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. 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. 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. 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. 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. 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.
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. Root marker
Aluminium
Cast Iron
Material with
Standard or
Custom design
Fibreglass
Reinforced
Plastic [FRP]