What is the purpose of a shield wire in transmission lines?

The purpose of a shield wire in transmission lines is primarily to protect against lightning strikes. In high-voltage transmission systems, shield wires are typically placed above the main conductors. Their role is to intercept and safely conduct lightning strikes to the ground, thereby preventing damage to the conductors and the equipment connected to the transmission line. By providing a direct path for lightning currents to follow, the shield wire helps to minimize the chances of flashover and equipment failure, which could result from a direct lightning strike to the transmission line.

In this context, the other options do not align with the primary purpose of the shield wire. While enhancing signal strength, stabilizing voltage, or increasing current flow are all important factors in electrical transmission, they are not functions served by shield wires. Instead, the shield wire’s protective role is crucial in ensuring the safety and reliability of the transmission system.