To unload an overloaded radial transmission line, what action must the Transmission Operator take?

• A. Raise interchange schedule
• B. Lower interchange schedule
• C. Re-dispatch generation
• D. Shed load at the end of the line

Answer: (D)

To unload an overloaded radial transmission line, the appropriate action involves shedding load at the end of the line. When a radial line is overloaded, it typically means that the demand on that line exceeds its capacity to safely carry the electrical load.

By shedding load, the Transmission Operator can quickly reduce the amount of electricity being drawn at the end of the line, which decreases the current flowing through the line. This action is essential because it directly addresses the overload condition and helps protect the infrastructure from potential damage due to excessive current flow, which can generate heat and risk equipment failure.

This approach is often more immediate and effective compared to other potential actions, such as altering interchange schedules or redispatching generation. While changing generation output may eventually help balance loads and generation across the grid, it can take time to implement these changes and may not resolve the issue as quickly. Therefore, shedding load at the end of the line is a direct and strategic method to ensure the safe operation of the transmission system.