Electrical cables are used in every sector which are used in transporting electrical energy from one point to another. These cables are composed of materials that are electrically conducting with an outer insulating cover. When the cables are connected to the corrected terminal of the the application allows them to carry the power or current into them. These cables are used for the distribution of electrical power to various destinations. They transmit high-voltage power where the overhead lines are impractical to use and implement. There purpose of electrical cables is to transport the electrical energy from one point to another destination. The electrical cables are an assembly of one or more wires that are twisted with each other and are used as conductors for carrying electrical current. These cables can have different configurations based on their design on national and international regulations.
Table of Content
What is an Electrical Cable?
The electrical cables are the medium by which they distribute and transmit electrical power at different destinations. These cables are capable of transmitting high voltage to various connected destinations. The cable is used for the distribution and the transmission of the electrical cable where overhead lines are impractical to use. Cables are generally made using copper as it is a good conductor of electricity. Copper is easily available but sometimes aluminum is also used in cable as it is more cheaper than copper and a good conductor.
An electrical cable is generally composed of three things:-
- Conductor : It is used for transmitting electricity. The most commonly used conductors are copper and aluminum. The conductor in the wire provides the conducting path to the cables.
- Dielectric : For isolating the conductor from other things and preventing it from an unintended path. Different synthetic polymers are used for insulation. The dielectric (insulation ) withstands the voltage and it isolates the conductor to come in contact with another object.
- Sheath : It is a protection layer to the wires from external influence or atmosphere. commonly used sheath material is PVC. The sheath protects the cable from external influences like human touch, water spills, chemicals, etc.
Classification of Cables
The cables are generally color coded. Different colors of wires have different color for different purpose. The color code for AC and DC also varies accordingly. There are generally three colors for DC:-
- Red: Positive current
- Black : Negative current
- White or Grey : Ground wires
The generally colors codes for AC (120/220/240):-
- Black : Phase 1 lines are black used for power generation.
- Red : Phase 2 or transmission wires.
- Blue : Phase 3 or distribution of power wire.
- while : Neutral wire.
- Green or Green with yellow strips : Ground wire.
The color’s of the electrical cables are governed by the International Electrical Commission Standard IEC 60446.
Types of Electrical Cables
Some types of electric cables are as follows:
- Network Cables
- Cables for electric Panels
- Armored Cables
- Rubber Cables
- RHZ1
- Solar Cables
- RHVhMVh
- HEPRZ1
Network Cables
The function of cable depends on the type of cable used – the material and the protection used for that material so based on some terms the cables are classified from which network cable is used for the transmission of the signal.
These cables consist of :
- Coaxial Cable:- It is also called coax cable. These cables consist of a conduction core which is surrounded by the some other conducting layer. These both layers in cables are separated by the insulator. The complete setup is given an outer protection. Coax are used for transmitting very high frequency signals with very less loss of energy like for appliances like radio, antennas, transmitters. This can also be used for the computer networking and other networking processes.
- Twisted Pairs Cables :- In this cable the two cables are twisted together and are color coded. These have very less probability of interference. They are used in ethernet networking system. This type of cable is basically used for the telephone cables and the resistance can be measured by the number of wires used.
-
Optical Pairs:- The optical file cables are made of glass surrounded by the the protective layers. These cables works on the principal of total internal refection (TIR) for transmitting light due to this it have almost zero energy dissipation. These cables have a core called cladding which is optically rarer than the core. The transmission of electromagnetic wave reflects in the core cladding.
Optical fiber cable is of 2 types:-
1. Multi Mode fiber(Short-Range)
2. Single Mode (Long-Range)
- Patch Cables :- These cables are used for connection or “Patch” with different devices.
- Internet Cables:- These cables are ethernet cables. Ethernet cables are used for connecting a device or any game console to a modem. These transfer data across the internet.
Cables for electric Panels : These types of cables are suitable for domestic purpose, for installation in public area and for any internal wiring, switch boxes.
Armored Cables
These cables are made of aluminum or steel which are installed for risk of mechanical aggression. These are used in making heavy structures like where rodents are present.
Rubber Cables
The cables are highly flexible which are used in fixed industrial installation as well in mobile services. The cables which are used in welding should be covered with rubber sheath, which helps in flow of high current to be transmitted between the welding generator and electrode.
Solar cables
These are specially designed cables which are suitable for photo voltaic panels and from panes to DC to AC inverter. It is specially resistant to solar radiation and extremely high temperature.
RHZ1
This is a medium voltage cable with XLPE insulation, halogen free and non flammable. These are perfectly used for transportation and distribution of energy.
HEPRZ1
It is also a medium voltage category cable which is also halogen and non-flammable. It is ideal for transportation and distribution energy.
RHVhMVh
These cables are made of copper and aluminum. It a medium voltage carrying cables designed for special applications. It is specially designed for the area where risk of oils and chemical agents are present.
Nomenclature of Electrical Cables
|
Symbol |
Meaning of Symbol |
|---|---|
|
R |
Crosslinked polyethylene (XLPE) |
|
Z |
Cross-linked polyethylene (XLPE) |
|
Z1 |
Halogen-free thermoplastic polyolefin |
|
S |
Halogen-free thermosetting silicone compound |
|
D |
Ethylene-propylene elastomer (EPR) |
|
Z |
Halogen-free thermosetting elastomer |
|
V |
Polyvinyl chloride (PVC) |
Measurements of Electrical Cables
|
CROSS-SECTION in mm2 |
(AWG) |
CURRENT CONSUMPTION |
|---|---|---|
|
25 mm2 |
4 |
Very High |
|
10 mm2 |
8 |
Medium High |
|
6 mm2 |
10 |
Medium |
|
2.5 mm2 |
14 |
Under(Less) |
|
1.5 mm2 |
16 |
Very Low |
Composition of Electrical Cables
Composition of Electric Cables
Every electrical cables is composed of following elements :
- Conductor : This part of the cable allows the electrical current. It can be made of different metallic materials and made of many multiple threads. It is generally made of copper as it is easily available in nature with low cost. In many different case the aluminum is also used as conductors.
- Insulation : It is the cover to the conductor to prevent it from outside environment and also prevent it from flowing the outside it. The insulation are made of polymer, plastic layer that cover the conductor it from external contacts. The PVC is the most commonly used thermoplastic insulation has maximum temperature tolerance of 70. The higher the temperature tolerance the more the conductor can can carry the current.
- Shielding or Armor : It is the external protection of the conductor against the temperature, sun, rain etc. These are generally made of polymeric material. These are applied to isolate the signals that pass through the inner side of the cable and prevent it from external interference.
- Protection or Outer Sheath : In current time every cable have an outer sheath is used of protecting the cable. These are generally made of polymeric material and these are used according the the environment conditions. It isolates the electromagnetic field in the cable from any external electromagnetic field.
Voltage Rating for Electrical Cables
The basic and fundamental ratings that are assigned to an electrical cables is voltage rating. The rating of the electrical cables defines the purposed for which they are deigned.
rated voltage = U0/U
where : U0 is r.m.s value between any conductor and insulator.
U is the r.m.s value between two phase conductor of a multicore cable.
|
Size and material |
Insulation Material |
Maximum Operational Temperature |
Rating |
|---|---|---|---|
|
120 sq-mm Copper Conductor |
PVC Insulation |
700 C |
13.80 KA/SEC |
|
120 sq-mm Aluminum Conductor |
PVC Insulation |
700 C |
9.12 KA/SEC |
|
120 sq-mm Copper Conductor |
PVC Insulation |
850 C |
KA/SEC |
|
120 sq-mm Aluminum Conductor |
PVC Insulation |
850 C |
KA/SEC |
Cable Rating Table
|
Cable Cross Section Area(mm2) |
Typical Current Rating (amps) |
Recommended Circuit Breaker (amps) |
|---|---|---|
|
1.5 mm2 |
7.9-15.9A |
8A |
|
2.5 mm2 |
15.9-22A |
15A |
|
4 mm2 |
22-30A |
20A |
|
6 mm2 |
30-39A |
30A |
|
70 mm2 |
147-180A |
150A |
|
150 mm2 |
250-287A |
275A |
|
240 mm2 |
334-400A |
350A |
Properties of Electrical Cables
- Strength and flexibility : The cables which are used for any purpose must have a large insulation and should be easily installed.
- Fire Resistant : The cables which are installed should be resistant to fire accidents.
- Long life and Heat Resistance : As the cables are installed every sector show they should require very less maintenance as it is not feasible to maintain them in public or private facilities. The installed wiring should be heat resistant.
- Simple Usage : The cables should be easily installed without requirement of complex circuits .
- Cost Effective : Cables are used every where and backbone of electrical circuits. This makes it important to ensure that they are available at fair price.
Conclusion
In the current where every where it is a web of wires and cables at every place the cables play a very vital role in transmission and distribution of electrical power. These are very important for various application like power generation, distribution and transmission. These cables are made of highly conducting material such as copper and aluminum which are easily available in nature. They are also insulated with insulating material to prevent them from exposing them to atmosphere. Different types of cables are used at different requirement like Coaxial cables, twisted cable pair cables, etc. The color codes on the electrical cables help to identify their purpose of usage and helps in proper operation and installation. Overall the electrical cables are important for efficiently transportation of electrical power in every sectors.
FAQs on Cables
What is the difference between Wires and Cables?
The most generally use metals are copper and aluminum which are good conductor of electricity. These conductor in form of a stranded wire which are insulated with a polymer (non-conductive) coating is a wire while a cable is combination of two or more shielded wired with a single cover which is used for generation, distribution and transmission of electrical power.
Which cables are generally used for domestic use ?
The power cables are used for domestic purpose as they can be buries into the ground or can be used overhead.
Why we use shielded cables ?
We use shielded cables used when there is some unwanted electrical noise or some electromagnetic interference that the transmission of power. These are made of insulation conductors. These are generally used in airports, radio stations, for some heavy industrial purpose.