ALUMINUM AND COPPER CABLE

Electrical cable

An electrical cable is an assembly of one or more wire which are arrange side by side or in a bundled form and by the help of these cable we can transfer electric current or signal from source to destination.

Construction of cable

A cable have following main components
1-CONDUCTOR
Conductor is the main component of the cable and by the help of the conductor current will flow through the cable. Mostly two type of Cables are use in day-today life
i-Copper(Cu) cable
As Copper have low resistance and better conductivity therefore copper cable are mostly used for signal transmission and controlling the device by sending the signal that is why it is also known as Control cable.
ii-Aluminium(Al) cable
As Aluminium are lightweight and low cost therefore Aluminium is mostly used for power transmission and aluminium cable are also known as power cable.

2-INSULATION(OR DIELECTRIC)
By the help of dielectric(or insulation) we provide an isolation between the conductors within the cable. Most commonly used dielectric in cable are polyvinyl chloride(PVC), Cross-linked polyethylene(XLPE), poly chloro prene(PCP),paper, HDPE(High Density Polyethylene), etc.

3-BEDDING(or also called as inner sheath or inner jacket)

Bedding(or also called inner sheath or inner jacket)

It helps to provide circular shape to the cable and used to provide a protective boundary to inner and outer layers of the cable. 

4- OUTER SHEATH
The sheath of a cable is provide outer protection to the cable by the help of which we protect our cable from external environmental condition such as moisture, external temperature, external electro-chemical attack, fire, etc. The Sheath also provide mechanical strength to the cable. Most commonly used sheath in cable are polyvinyl chloride(PVC), Cross-linked polyethylene(XLPE), Ethylene propylene Rubber(EPR)

outer covering of the cable also known as:-

Jacket:- In case of signal cable outer covering of the cable is normally called jacket of the cable.

Serving:- In case of HT cable outer covering of the cable is normally called Serving of the cable.

Outer Sheathed:-In case of LT cable outer covering of the cable is normally called Outer Sheathed of the cable.

5- SCREEN ON THE CABLE

Screen means a conducting layer on the cable, Which is used to neutralize extra electrons. In case of HT Cable metallic screen also help in increasing the heat dissipating power of the cable.

6- SEMICON(Extruded semiconducting compound) in case of HT cable

The Semicon layers prevent air-filled cavities between metal conductors and dielectric, so that electric discharges cannot arise and voltage will be uniformly distributed throughout the cables. This layer is present on the cable above 3.3KV.

Note:-Semicon is a XLPE insulating tape that has some conductive material as additive.

 

Mechanical protection

In some case we need to provide the mechanical protection to our cable therefore we can distinguish cable according to its protection 
1-Armoured cable

Armouring as name suggests it is a protection. So, In case of Armoured cable usually Galvanised Steel is used for protection of the cable. This type cable is mostly used underground power or signal transmission because they do not bend easily.
In case of Armoured cable we are mostly do bedding. Bedding is a process of surrounding that cable by hessian cloth tape and jute, as a result cable get protection form mechanical injury due to armouring. It is just like a shock absorber.

In case of an armoured cable the outer insulation also know as serving.
NOTE:-Mostly XLPE Insulation is used in Armoured cable.

NOTE:-Generally in case of Armoured, In Aluminium armoured  we get solid Aluminum conductor up to 10mm. In cupper armoured we get solid cupper up to 6mm.

Type of Armouring cable

SWA:-Steel Wire Armoured cable(W Or SWA)

Steel strip Flat armoured(F)

STA:-Steel Tape Armoured cable(STA)

Copper Tapped Armoured cable(CT)

2-flexible cable

The cable without armouring are known as flexible cable as these cable can be easily bend therefore they are used within wiring of house or company 

NOTE:-In a multi-core cable the cores are identified by color-coding by using different colors on insulation or by number printing on cores

Classification of cable on the voltage

Low tension(LT)[or Low voltage]
It is used up to 1kv(1000V)
High tension(HT)[or High voltage]
It comes in range of 3.3KV to 33KV in some of the company in the India such as polycab (3.3kv, 6.6kv, 11kv, 22kv, 33kv).
In case of HT electrical distribution the system can be earthed or unearthed (if system neutral is not grounded).The selection of earthed/unearthed cable will depend on the system.

The HT cable again divide into two part

i-Earthed(E) cable
In three phase earthed system, phase to earth voltage is 1.732(√3) times less than phase to phase voltage. Therefore voltage stress on the cable to armor is 1.732(√3) times less than voltage stress between conductor to conductor.
So earthed cable stress is 1.732 times less than as compare to Unearthed(UE) cable
ii-Unearthed(UE) cable
As on unearthed cable has more stress(1.732√3 times) as compare to earth cable therefore. The unearthed cable has more insulation strength as compared to earthed cable. As a result the voltage carrying capacity of unearthed cable is more than earthed cable. The 6.6kv unearthed cable can with stand with voltage of 11kv(6.6X√3=11.4312), therefore generally people says that 6.6kv unearthed cable is equal to 11kv earthed cable.

Standards in the cables

Cable standards are most important criteria which decide thickness of insulation, armouring and test passed by the cables almost every country have its own standard for wire and cable.

IS:-Indian Standards published by Bureau of India Standard(BIS)

BS:-British standards

IEC:-International Electrotechnical Commission

EN:-European standards

VDE:-Verband De Elektrotechnik (German standards)

NF:-France standards

UL:-USA standards

JIS:-Japanese standards

Code in the cable

A2XFY

A=Aluminium

2X=xlpe insulation.

F=Steel strip Flat armoured

Y=PVC outer sheath

A2XWY

A=Aluminium

2X=xlpe insulation.

W=Round Wire armoured

Y=PVC outer sheath

Annealing process

Annealing is a heat treatment process. Annealing process increase corrosion resistance of a metal improve the electrical and thermal conductivity of a metal increasing toughness, reducing hardness and increasing the ductility and machinability of a metal.

Stain hardened(H)[ or work hardening process]

Stain hardened(H) is a process to increase the hardness and strength of metal by plastic deformation.

The first digit after the H indicates a basic operation

H1 – Strain Hardened Only.

In H1 material is strain hardened without thermal treatment.

H2 – Strain Hardened and Partially Annealed.

H3 – Strain Hardened and Stabilized by low temperature heating.

H4 – Strain Hardened and Lacquered or Painted.

In aluminium cable manufacturing we use h2, h4 grade plain aluminium conductor that possesses high tensile strength.