When a transmission line becomes radial due to the loss of a parallel line, what challenge does this present?

When a transmission line operates in a radial configuration due to the loss of a parallel line, it presents a higher risk of overload. In a typical transmission setup, parallel lines can share the load, distributing the electrical flow effectively. If one of these lines fails or is taken out of service, the remaining line must carry the entirety of the load that was previously shared. This increased load on a single line can exceed its capacity, leading to overheating and potentially causing equipment failure or outages.

In contrast, increased stability, load capacity, and lowered maintenance costs would not accurately characterize the situation. Increased stability implies that the system can handle disturbances effectively, whereas, in this scenario, losing a parallel line often destabilizes the system. The load capacity is effectively reduced as the remaining line can only handle its established maximum without the additional support from the lost line. Maintenance costs are typically influenced by system stress; higher loads on the remaining line can lead to increased wear and tear, likely raising maintenance requirements and associated costs over time.