At what voltage levels are transmission lines usually energized?

Transmission lines are typically energized at high voltage levels to efficiently transport electricity over long distances. The range of 230kV to 765kV is significant because these voltage levels minimize electrical losses during transmission. The high voltage reduces the current flowing through the lines, which in turn decreases I²R losses (the heat generated due to resistance in the conductor). This enables power utilities to deliver electricity from generation sites (like power plants) to substations without losing a substantial amount of energy.

Additionally, operating at these elevated voltages allows for the interconnection of a wide geographic area, supporting the transmission of larger amounts of power. This is essential for ensuring a reliable and stable electrical grid, especially as demand fluctuates throughout different regions.

In contrast, the other voltage ranges mentioned in the choices typically pertain to distribution lines rather than transmission lines. Transmission primarily takes place at much higher voltage levels, which is essential for long-distance and efficient power transfer.