The excitation of electrons in the wire’s conductor material is described by resistance in a wire. Heat is produced as a result of this excitation, and efficiency is lost. Due to resistance over distance, Thomas Edison couldn’t deliver his early DC power over a long distance without employing wide-diameter copper cables.
Why isn’t copper used in electrical wires?
1. Although copper is an excellent conductor of electricity, we employ aluminum in transmission lines.
The expense is the primary reason for not using copper.
Copper has a higher conductivity than aluminum.
Copper, on the other hand, is substantially more expensive than aluminum.
As a result of the cost, we’ve chosen aluminum over copper.
The conductivity of Cu and Al can be seen in the image.
Why aren’t overhead wires made of copper?
Copper was once the chosen material for overhead conductors, but aluminum has since supplanted copper due to the aluminum conductor’s lower cost and lighter weight when compared to a copper conductor of the same resistance. Some materials that are good conductors are listed below.
- Copper is a metal with a high conductivity and tensile strength. Copper in hard drawn stranded form is hence an excellent choice for overhead lines. Copper has a high current density, which implies it can carry more current per unit area of cross-section. Copper conductors have a smaller cross-sectional area as a result. Copper is also long-lasting and has a high scrap value. Copper, on the other hand, is rarely utilized for overhead power lines due to its higher cost and scarcity.
- Aluminum: Aluminum has roughly 60% the conductivity of copper, which means that the diameter of an aluminum conductor is around 1.26 times that of a copper conductor for the same resistance. An aluminum conductor, on the other hand, is almost half the weight of a copper conductor. Aluminum’s tensile strength is also lower than copper’s. Aluminum outperforms copper in terms of cost, conductivity, tensile strength, weight, and other aspects. As a result, aluminum is commonly utilized in overhead conductors.
- Cadmium-copper alloys have a copper content of 98 to 99 percent and a cadmium content of up to 1.5 percent. The addition of roughly 1% cadmium to copper enhances the tensile strength by up to 50% while only reducing the conductivity by about 15%. As a result, cadmium-copper conductors can be used over extremely long distances. Such conductors, however, may be uneconomical in many circumstances due to the high cost of cadmium.
- Other materials that carry electricity include a variety of metals and alloys. Although silver is more conductive than copper, it is not practicable in most circumstances due to its expensive cost. Steel that has been galvanized can also be utilized as a conductor. Although steel has very high tensile strength, steel conductors are not suitable for transmitting power efficiently due to the poor conductivity and high resistance of steel. Extreme circumstances may necessitate the usage of high-strength alloys such as phosphor-bronze.
Aluminum conductors, as previously stated, offer an advantage over copper conductors when considering cost, conductivity, tensile strength, weight, and other considerations. Because of their cheaper cost and weight, aluminum conductors have totally replaced copper conductors in overhead power lines. Even if an aluminum conductor has a wider diameter than a copper conductor of the same resistance, when ‘Corona’ is taken into account, this is an advantage. The diameter of the conductor has a significant impact on the corona. The four most prevalent types of overhead conductors used for overhead transmission and distribution to transport generated electricity from producing stations to end customers are listed below. In order to maximize flexibility, all types of conductors are often stranded. Solid wires are difficult to handle, with the exception of a very small cross sectional area, and they also tend to crystallize at the point of support due to swinging in the wind.
This type is also referred to as ASC (Aluminum Stranded Conductor). It’s made up of EC (Electrical Conductor) grade aluminum strands. The conductivity of an AAC conductor is roughly 61 percent IACS (International Annealed Copper Standard). Despite its high conductivity, AAC’s employment in transmission and rural distribution lines is limited due to its low strength. However, AAC is used for distribution in urban settings where spans are often short but better conductivity is necessary.
Aluminum alloy 6201, a high strength Aluminum-Magnesium-Silicon alloy, is used to make these conductors. This alloy conductor has a high electrical conductivity (about 52.5 percent IACS) and a high mechanical strength. AAAC may be utilized for distribution due to its reduced weight as compared to ACSR of identical strength and current capacity. It is not, however, commonly used for transmission. AAAC conductors can also be used in coastal environments due to their high corrosion resistance.
ACSR is made up of a solid or stranded steel core wrapped in spiral with one or more layers of high pure aluminum (aluminum 1350) wires. The core wires can be zinc-coated steel (galvanized) or aluminum-coated steel (aluminized). A thin galvanization or aluminization coating is applied to steel to protect it from corrosion. Because of the added mechanical strength provided by the center steel core, sag is greatly reduced compared to other aluminum conductors. ACSR conductors come in a variety of steel content options, ranging from 6% to 40%. When greater mechanical strength is required, such as when crossing a river, ACSR with a higher steel content is chosen. ASCR conductors are widely employed in all aspects of transmission and distribution.
Wrapping strands of high purity aluminum (aluminum 1350) on a high strength Aluminum-Magnesium-Silicon alloy (6201 aluminum alloy) core creates the ACAR conductor. ACAR conductors have better electrical and mechanical qualities than ACSR conductors. ACAR conductors are suitable for both overhead transmission and distribution lines.
Are the power wires in the sky made of copper?
Towers for line support are built of wood (either grown or laminated), steel or aluminum (either lattice structures or tubular poles), concrete, and reinforced polymers on occasion. Although some copper wires are used in medium-voltage distribution and low-voltage connections to customer premises, the bare wire conductors on the line are often composed of aluminum (either plain or reinforced with steel or composite materials such as carbon and glass fiber). One of the main goals of overhead power line design is to keep enough space between energized conductors and the ground to prevent dangerous contact with the line, as well as to provide reliable support for the conductors and resilience to storms, ice loads, earthquakes, and other potential damage sources. Today, overhead lines are commonly operated with voltages between conductors surpassing 765,000 volts.
Why are overhead cables made of aluminum rather than copper?
When comparing aluminum to copper, keep in mind that it conducts less well. Copper, on the other hand, is a lot heavier. Aluminium has a density that is just one-third that of copper. As a result, the light weight of aluminum is the primary justification for its use in overhead connections rather than copper.
Copper is utilized in electrical cables for a variety of reasons.
Copper is the conductivity gold standard. Copper is more efficient than any other electrical conductor due to its high current carrying capability. Annealed copper is the international standard against which all other electrical conductors are measured due to its higher conductivity.
What kind of overhead wire is used?
The brief explanation is that, due to its particular qualities, aluminum is the best material for overhead wires in general. Aluminum wire is ideal for long-distance lines because of its low density, low cost, and great electrical carrying capability.
In overhead lines, what type of insulator is used?
Insulators are transmission system components that provide essential insulation between line conductors and supports, preventing any current leakage from the conductors to the ground.
The overhead transmission lines’ line conductors should be supported on poles or towers in such a way that current from the conductors does not flow to the earth through the supports, which implies the conductors must be adequately insulated from the supports. Insulators are used between the line support and conductors to accomplish this.
Porcelain is the most popular material used to make insulators for overhead transmission lines. Glass, polymer, and steatite, as well as a variety of other unique composition materials, are used to make overhead line insulators. Porcelain is mechanically stronger than glass, is less prone to leakage, and is less affected by temperature changes.
For overhead transmission lines, what conductor is used?
Alloy Aluminum Conductor ACAR conductors that have been reinforced can be used in both overhead transmission and distribution lines.
Why is aluminum increasingly being used instead of copper in electrical cables?
Although silver is the best conductor of electricity, its expensive price prevents it from being widely used. As a result, aluminum and copper cables are the most commonly utilized conductors. The conductivity of copper is higher than that of aluminum.