Professional Answer: A 500kV line is classified as an Extra High Voltage (EHV) transmission line. It is primarily used for the bulk transfer of electrical energy over very long distances. The high voltage level is chosen to significantly reduce power losses during transmission, as power loss is proportional to the square of the current (Ploss∝I2R). By increasing the voltage, the current can be lowered for the same amount of power, resulting in a dramatic reduction in losses. This makes 500kV lines critical for connecting major power generation centers, such as large power plants or renewable energy farms, to distant load centers.