If a transmission line is loaded above its System Interaction Limit (SIL), what happens to the voltage?

When a transmission line operates above its System Interaction Limit (SIL), it is subjected to increased reactive power flow due to excessive loading. This situation often leads the line to behave more inductively. Inductive behavior occurs because as the load increases, the line tries to draw more reactive power to maintain the voltage level.

As a result of this increased inductive characteristic, the voltage at the receiving end typically experiences a drop. The line struggles to supply sufficient reactive power to support the voltage under heavy loading conditions, and the overall system stability can be compromised. It is essential to monitor and manage transmission lines within their acceptable limits to maintain operational integrity and prevent voltage drops that could lead to further complications in the electrical grid.

Understanding the impacts of loading above the SIL is crucial for maintaining the reliability of the transmission system, as it directly influences voltage levels and system stability.