Manufactuing
of Cables
Cables with Aluminium and Copper conductor and polymer
insulation are manufactured at Works at Delhi.
Essentially cables comprise of conductors, insulation,
innersheath, armour and outersheath.
| Conductor |
| . |
Cables are available with both
aluminium and copper conductor. |
| . |
Cables are
manufactured with solid/ stranded circular/ shaped
Aluminium/ Copper conductor.
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Stranding
makes Cables flexible and easy to handle while shaping
makes them compact.
|
Compaction
is provided to all stranded conductor constructions as
under:
-
Circular
Conductor: With
one wire in the center conductor contains 6,12,18,24,30......
wire layers in either unilay or opposite helical directions.
The conductor is Compacted.
-
Shaped
Conductor:
In all multicore cables from 16 Sq.mm. size, conductors
are "Shaped". However 6 & 10 Sq.mm. conductor can
be solid/stranded circular.
National
specifications - 8130
Insulation
Insulation for
Cables is strictly as per National
and International specifications.
Cables are designed and manufactured
with polymer dielectrics to bear thermal and thermomechanical
stresses safely at continuous normal and short circuit
temperature conditions.
Cables
are available with both thermoplatic & thermo setting
insulations.
PVC
Cables - Thermoplastic dielectric
XLPE Cables - Thermo setting dielectric
PVC Cables use PVC Compounds that take care of over load
and short current with both course & fine protection
systems.
XLPE cables use XLPE Compound with antiu-oxidant stablizers
and traces of aromatic polunuclear hydrocarbon. Thus improving
electrical treeing characteristics and mechanical strength
of insulation.
Pair
Screening
Two core are twisted to make a Pair. A tape of Polyester
is applied over the Pair and then another tape of Aluminium
Mylar is applied alongwith Drain wire.
Laying
Up
Cores are tested on line during production both for physical
and electrical characteristics. Control is observed within
tight tolerance limits for dimensions in case of PVC/XLPE
insulation.
Overall
Screening
A tape of Polyester is applied over the laid up pairs
and then Aluminium Mylar is applied along the Drain wire.
Inner
Sheath
Laid up cables are provided with innersheath of Tape/Extruded
PVC with high quality of PVC which acts as bedding for
steel wire/strip armouring and circularity is maintained.
In
Cables - polymer used for innersheath
are softer than insulation or outersheath & are compatible
with temperature ratings of cables & do not have deleteriocus
effects on any other component of cable.
The
innersheath dimensions are maintained strictly in accordance
with laid down specification.
Specification
For PVC Cables - IS:1554 (Part-I)
For XLPE Cables - IS: 7098 (Part-I)
Armouring
Mechanical protection to the cable is provided with armouring.
single core cables are armoured with Aluminium or Aluminium
wire/strips, thus avoiding magnetic hysteresis losses
on A.C. system.
Multicore
cables are provided with galvanized steel wire/strips.
Cables
are provided with galvanized wire armouring, where cables
are to run vertically and are subject to strsses
Cables armour
wire/strips are of low resistivity material and meet the
requirements of IS: 3975.
Outersheath
All
Cables
are provided with PVC/HR PVC/FR/FRLS outersheath.
Cables are
manufactured with various characteristics of sheathing
compounds.
| General
purpose sheathing copound |
|
ST-1 |
| Heat
resistant Compound for sheath (H.R.) |
ST-2 |
| |
|
| Fire
Retardant Low Smoke Compound (FRLS) |
IEC
754 Part I
IEC 60332 Part I & II
IEEE- 383
ASTM- 2843
ASTM- 2863 |
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Ultra
Violet Radiatoins Resistance Compound to ASTM G-53
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Anti
Rodent and Anti Termite Compound is applied where
the customer ask for it.
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PVC
Compounds used for
Cables are of various grades
to meet specifications IS: 5831.
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In
order to be identified,
Cables have their names embossed/printed/intended
on outersheath at regular intervals.
Cables
are sequentially marked for length at every metre throughout
its length.
Final
Testing
Each
Cables
is tested for all applicable Routine Tests. From a lot
of Cable one cable of each type is tested for Type Tests,
as per relevant specifications.
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