Cables and conductors form an integral part of an electrical network. The use of good quality cables that meet the specific needs and requirements of a particular electric network is essential to maintain a secure and robust network. Therefore, there has been a growing demand for specialised cables for different segments such as solar power, data centres and nuclear power. These cables are designed to meet specific conditions such as temperature, pressure and wind speed encountered in the electrical network in different segments. Besides, often cables for specialised segments undergo various tests to withstand environment hazards, temperature and aging to gauge the suitability of the cables for precise segment functions.
Solar cables are designed to suit the specific purpose of evacuating solar energy from photovoltaic (PV) modules. These cables are connected between individual modules and the string combiner box. Solar direct current (DC) cables are broadly of two types – module cables or string cables and DC main cable. Module cables/string cables are usually integrated into PV solar panels and are equipped with suitable connectors to be interconnected. On the other hand, DC main cables are special extension cables that are used to connect positive and negative cables from strings to the generator connection box (or directly to the solar power inverter). DC cables are used outdoors. These DC cables between modules as well as between the generator connection box and solar power inverter are two-core cables, a current-carrying usually a live red wire, and a negative blue wire; both are typically surrounded by an insulation layer.
With regard to the key characteristics of solar cables, they have a high thermal rating to withstand extreme temperatures, as they are specially designed to be strong in extreme weather conditions. In addition, these cables have high resistance to heat pressure, and have superior abrasion and notch resistance. Solar cables are designed to have resistance to ultraviolet rays (UV) and weather changes as well as suitable for wet locations. They can be used within a large range of temperatures and are generally laid outside. For solar tracking panels, the cables need to be flexible as the panels keep moving along with the sun.
A key consideration while selecting the solar cable is to use the correct cable size when connecting various components of a solar PV system. Correctly sizing the solar cables ensures that there is practically no overheating and loss of energy is minimised. Using an undersized cable not only poses a potential risk of causing a fire due to overheating and causing damage to the equipment. Broadly, the size of the wire to be used depends upon the generating capacity of the solar panel (the larger the quantity of current generated, the bigger is the size) and the distance of the solar panel system to the loads (for greater distance, a bigger sized wire is used).
Cables for data centres
Cabling infrastructure is at the core of every voice, data and multimedia network. It is the key to data centre availability and manageability. Ensuring proper planning, configuration and installation for connectivity in a data centre is essential; otherwise, it can cause inefficiency and excessive heat in the system. The devices in a data centre require physical cabling. For improved performance and flexibility, it is essential to ensure that the cabling infrastructure is reliable, scalable and manageable.
Cabling within a data centre may be either structured or unstructured. Structured cabling uses predefined standards-based design with predefined connection points and pathways. The cabling used in a structured wiring design is specified by the bandwidth requirements of the system and is tested to ensure proper performance. The cables used in a structured wiring system are well organised and labelled. Although a structured cabling system may take longer to install and have a higher initial cost, the operational cost will ultimately be lower and the life cycle of the system will be longer, compared to an unstructured system. Unstructured, also known as “point-to-point”, cabling systems do not use predefined standards, connection points, or pathways. This type of cabling system can lead to cooling issues because the airflow is typically restricted. This may also lead to higher energy cost. Additionally, managing system growth becomes difficult because of the lack of a plan to change cable locations or run new cabling. An unstructured cabling system is inherently unreliable and may result in extended downtime. Although an unstructured cabling system may take less time to install and have a lower initial cost, the operational cost will be higher and the life cycle will be shorter, compared to a structured system.
The key network cable options used in a data centre are AC/DC power, ground, copper and fibre optic cables. The interface that is available on the equipment used in the data centre is the primary means for determining which type of cabling should be used. The network data cabling may also be selected based upon the bandwidth requirements of the equipment being used in the data centre. Dynamic data centre environments call for a great deal of flexibility in connectivity, and the objective is to implement a cabling system with copper and fibre media capable of transmitting ethernet, fibre channel, and any other protocols specific to the environment. Further, planning for growth, expansion and technology upgradation for undertaking cabling in a data centre is expected to lead to significant cost and time savings in the future.
Other specialised segments
Specialised cables are used for various other segments depending upon their needs and requirements. Various cables used in wind power plants are designed to meet particular requirements. Copper cables are used for the transmission of temperature signals to control the operating temperature with the help of resistance thermometers. The data cables that are used are highly flexible, which are installed from the housing to the base of the wind power plants. On the other hand, cables used at nuclear power plants are designed to operate at high temperatures, and these are required to satisfy various thermal ageing tests, radiation resistance tests, as well as fire performance and environmental performance tests. Nuclear cables are designed to meet a life expectancy of 40-60 years. Apart from this, different kinds of cables such as high voltage cables and elastomer cables are being designed to meet the individual requirements of various segments such as mining, oil and gas, and railways.
To conclude, greater focus is expected to be there on cables for individual applications pertaining to the industry needs. Going forward, there is likely to be significant demand for cables from the mining, oil and gas, and metro railway segments. Meanwhile, with the growing thrust on the development of renewable energy in the country, the demand for cables for solar and wind plants is expected to remain high in the coming years.