These networks together form a complete Transmission and Distribution system but the function of both the systems is marginally different from each other. The main function of Transmission system is to deliver bulk power from generating stations to the load centers and large industrial consumers who are residing beyond the economical service range of regular primary distribution lines. The power is further stepped down in substations where it is distributed to domestic and commercial users. The power can be transmitted either employing overhead system or underground system.
In early days conductors used on transmission and distribution lines were usually copper. But aluminium conductors have completely replaced copper because of much lower costs and lighter weight of aluminium as compared to copper, having similar resistance. Aluminium Conductors are of different types such as (i) All Aluminium Conducts (AAC) (ii) All Alloy Aluminium Conductors (AAAC), (iii) Aluminium Conductors Steel Reinforced (ACSR), and iv) All Aluminium alloy conductor steel reinforced (AACSR). These are used in Transmission and Distribution system to carry the generated electrical energy from the generating station to the end user. The major difference between AAC, AAAC, and ACSR conductors are the materials they are constructed from. AAC is manufactured from electrolytically refined aluminium with .7% minimum purity. AAAC is made from an Aluminium alloy whereas ACSR contains a combination of Aluminium reinforced with steel.
AAC Conductors were developed as a consequence of the galvanic corrosion that ACSR Conductors are susceptible to. AAC is used as bus bars in substations, mainly in urban areas where the spacing is short and the supports are closer. Due to its property of high corrosion resistance, they can be extensively used in coastal areas.
The ACSR conductors are most commonly used for overhead transmission system, whereas AACSR and Extra high strength ACSR conductors are used for river crossing, where installation involves extra-long spans. The high tensile strength and balanced aluminium to steel ratio for weight and strength allows to use ACSR where longer spans with less support is required. The different strengths ACSR can be achieved by varying percentages of steel core. The major advantage of this type of conductor is that desired strength can be achieved without losing ampacity.
On the other hand, AAAC has large mechanical resistance than AAC which permits its use as a bare overhead conductor on aerial circuits for power transmission and distribution lines. It also has better sag characteristics and strength to weight ratio as compared to AAC. Its weight per unit and resistance is also lower which gives it advantage over the ACSR. Also, AAAC conductor has better corrosion protection than ASCR conductors. Due to these reasons, AAAC is most preferred conductors as compared AAC and ACSR.
Central and State Government are in continuous process to make power accessible to every corner of the country. Due to this massive, rural electrification programme and commitment have been initiated to electrify each and every house in a remote village.
Various reforms have been started to ensure electricity is reached to all section of society. This initiation has drastically increased the demand and scope of conductors and boosted the business of conductors manufacturing industries.