The subject of comparing the aluminum conductor Vs the copper made cable, whether it is in high or low voltage, never will get old or goes out of fashion. The wind turbine industry, as an example, follows certain standards which will change the preference in choosing suitable materials. In 2020, the wind energy industry celebrated another successful year by commissioning a total of 16,913 MW of capacity across the board. Since there are currently over 60,000 wind turbines in operation across 41 states, original equipment manufacturers (OEMs), asset owners, and independent service providers all keep up with the latest technological advancements in the industry in order to maximize the efficiencies of newly manufactured turbines and extend the life of their aging fleets. Manufacturers of wind turbines go to considerable lengths to ensure that their products have a commissioned life of at least 20 to 30 years, as this is the average that asset owners anticipate when making an investment in a technology that calls for so many dependable components. It is believed that a single wind turbine contains about 8,000 separate components, all of which are subjected to some of the most severe conditions. The American National Standards Institute (ANSI) approved UL 6141, also known as the Standard for Wind Turbines Permitting Entry of Personnel, in May 2016. UL 6141 has served as a guiding standard for initiatives related to electrical safety and has imposed a number of limits on cable design and installation practices that were previously considered standard. As a result of this endeavor, better cable installation procedures have paved the way, and the general architecture of the cable has evolved.
Condition monitoring systems (CMS) and preventative maintenance (PM) programs troubleshoot and keep these machines and their components operational for a very long time, but just like the tires on a car, after a certain amount of time and usage, they simply need to be replaced. This is analogous to the fact that these machines and their components can remain operational for a very long time. At the drip loop, tower cables travel over a cable guide that is referred to as a "saddle" on their way up to the nacelle just beneath the yaw deck. This is a prime example of a location within a wind turbine where cable quality can deteriorate over time. This dangling "swagged" bundle of cables gives the nacelle the ability to rotate, which in turn adjusts the orientation of the hub and the blades relative to the wind. When the nacelle rotates, these cables are subjected to continual twisting, bending, and even slapping into the middle of the yaw deck. This can cause damage to the cables. It is possible for thermal aging and abrasion to occur during installation if cables are not correctly managed and spread out. This results in the cables twisting against each other, which creates friction and heat, which in turn shortens the life of the cable jacket and/or the insulation. The management of cables has seen significant advancement with the development of more recent fleets, although more enduring problems still exist in older operational fleets. In wind power plants, a wide variety of cables and wires are utilized; however, the most prevalent types of cables and wires are either thermoplastics, such as PVC or PUR insulated cables, or elastomers, such as rubber cables. In theory, the same chemical and physical degeneration processes can be applied to all different kinds of materials. In addition, the process of aging in plastics is affected by a variety of other factors, both internal and external. The cable's service life is affected not only by the intensity of the load but also by the duration of the load, the type of load, the surrounding media, and other environmental factors. The following are examples of factors that contribute to the aging process of cables: Torsion Torsional cables are put through a function test that, according to the manufacturer of the wind turbine, ranges from 2,000 to 10,000 torsion cycles over the course of approximately 20 years of service life. Torsional cables have a life expectancy of approximately 20 years.
Vibration The rotor beat causes vibrations in the nacelle as well as in the tower. The wind turbine manufacturer is responsible for determining these vibrations in order to generate a test setup that corresponds to them. Abrasion: In order to produce torsion-resistant cables, the raw materials that are utilized should have a low potential for abrasion. This will allow for the best possible results to be obtained from friction and wear tests conducted on the jacket material compounds. Another element that contributes to the aging process is contamination with oils, which shortens the useful life of wires and cables. It is important to evaluate the oil resistance of a component not only with standard industrial oils but also with the specialized oils that are required for a wind turbine. The oil mist buildup that can occur from moving elements like gears, motors, and rotor hubs is not something that should be taken lightly. Temperature: the typical method for calculating thermal aging is based on the realistic Arrhenius curve, which approximatively describes a quantitative temperature dependency in both physical and, most importantly, chemical processes. This factor is primarily determined by the amount of force that is being applied to the object being aged. The thermal load, and more specifically the temperature of the conductor, has a significant impact on the rate of aging. If the maximum temperature allowed is consistently exceeded, the conductor insulation will age more quickly, which will result in a shorter amount of time that it may be used effectively. According to the "Van 't Hoff rule," the useful life of the insulation is cut in half for every 10 degrees Celsius (70 degrees Celsius to 80 degrees Celsius) when the operating temperature rises. In order to ensure a long service life, this should be taken into consideration while determining the dimensions of the cross section. The service life can be affected not only by the temperature of the environment, but also by the temperature dynamics (the range of temperatures from lowest to maximum).
Other aspects that play a role are as follows:
- oxygen content of the surrounding air at the current moment
- Ambient media (salt fog)
- Impurities (sand, solvents, etc.)
- UV exposure (outdoor system exposure or lattice mast tower)
- Radiation exposure and the wavelength of the radiation
- Ozone pollution (energetic radiation, electromagnetic fields) (energetic radiation, electromagnetic fields)
- Condensation of moisture and humidity (water treeing)
In conclusion, employing function and property tests to estimate the service life of cables and wires is merely a good approximation at best. The process of aging anything artificially in a heating cabinet is only one link in the cycle of aging. On the other hand, when the cable is used in the application for which it was designed, there is a possibility of superimpositions and interactions with various types of loads, which the user frequently cannot define or exclude. These factors basically hasten the natural aging process of the materials that are utilised. See DIN VDE 0304-22 / DIN EN 60216-2 or DIN VDE 0304-21 / DIN EN 60216-1 for more information. Essentially, the stabilization of the relevant material mixes is set, or the aging tests are defined, so that the cables hold for 20,000 hours at the prescribed temperature. An alternative to copper is the use of aluminum. Because of its superior ability to conduct electricity and its malleability, copper has established itself as the industry standard for cables and wires. On the other hand, as compared to aluminum, its cost is significantly higher. In many circumstances, an alternative choice would be to switch from copper to aluminum, which is not only considerably less expensive but also considerably lighter. To make effective use of the conductive metal aluminum, one must have a solid understanding of both the capabilities of aluminum and the strategies for overcoming the obstacles that the material poses. The three-month moving average price of copper in 2021 is $4,417 per ton, which is over four times as expensive as the moving average price of aluminum, which is $1,138 per ton (as of Aug 2021). Because there is a bigger supply of raw aluminum as opposed to raw copper, there is a significant price differential between the two. The uncertainty that surrounds the market for raw materials lends additional support to the evaluation of present prices.
Aluminum cables with Class B conductor stranding are being used more frequently by industrial customers for applications that are stationary. Additionally, more cables with more finely stranded conductors are being used for applications that require torsion resistance, such as in the nacelle. This is because rising metal prices have caused costs to rise, and industrial customers are keenly evaluating how to reduce costs and weight. When compared to the weight of copper as a raw material, aluminum is approximately 70 percent less in weight. This may be beneficial in the efforts of a variety of application industries that are aiming to lower the total amount of weight carried by all components. Naturally, the lighter weight makes it simpler to install electrical wires when they are employed in these applications. Aluminum has long been the material of choice for high-voltage cables due to its reduced weight, which greatly reduces the tensile tension that is exerted on wire and masts. However, many businesses, like the aerospace industry and the car production industry, are making the switch to aluminum wires. Aluminum is used in the production of each and every cable harness found in the Airbus A380. Wires made of aluminum can be up to 60 percent lighter than wires made of copper while having the same capacity to transmit current. Copper should not always be the first choice, even for applications that require flexible cable connections.