Answer: The Ferranti effect is a phenomenon where the receiving-end voltage of a long AC transmission line becomes higher than the sending-end voltage under light load or no-load conditions.

This happens because the line's distributed capacitance generates leading reactive power, which is greater than the lagging reactive power consumed by the line's inductance. This excess reactive power causes a voltage rise along the line. It's a significant concern because this overvoltage can damage sensitive equipment like transformers and insulation at the receiving end of the line.