What is the SIL loading capacity mentioned for a 500 kV line?

The SIL, or Surge Impedance Loading, refers to the maximum power that can be transmitted through a transmission line without causing voltage instability or significant losses. For a 500 kV transmission line, the typical SIL loading capacity is often recognized within the range provided in the answers.

The correct capacity of 850 MW indicates that at this load, the transmission line operates efficiently and at optimal voltage levels under normal conditions. This represents a balance where the reactive power consumed by the line matches the reactive power produced, preventing excessive voltage drops or spikes, which can compromise the integrity of the transmission system.

The context behind the specific value of 850 MW means that under standard operating conditions, the transmission line can handle this load effectively without necessitating additional compensation mechanisms to maintain voltage stability. Therefore, it is essential for planners and operators in the power systems to understand SIL, particularly when designing systems that require high efficiency and reliability in the transmission of electrical energy over long distances.