High-Voltage Transmission

This chapter deals with the explanation of high-voltage transmission. Reliable and economical transport of power from generating stations to the load centers is accomplished by overhead lines operating at a high voltage. Transmission by underground cables is limited to special cases and for short spans as in water crossings and in metropolitan areas. Voltage in excess of 69 kV is considered transmission, and voltage below 69 kV is considered distribution The conductor current for a given Kilovoltampere [kVA] rating is inversely proportional to the voltage used; hence the higher the voltage, lower is the current and even lower is the power losses occurring during the transmission process. The most popular conductor type used for transmission lines is the aluminum conductor steel reinforced (ACSR). Other conductor types such as all aluminum conductor (AAC), and all aluminum alloy conductor (AAAC) are also used and offer advantages such as higher operating temperature and low weight. The conductor size is determined by the current. The electric field on the conductor's surface and at any other point in space is determined by the voltage. For overhead lines, clearances to ground are determined both by the voltage and current. The chapter also discusses established methods that are employed for installation in-service. © 2005