Under what circumstance is a transmission operator allowed to disconnect from the interconnection?

The correct response centers on the transmission operator's responsibility to maintain system reliability and safety. A transmission operator may disconnect from the interconnection when equipment is endangered to protect both the equipment and the overall stability of the power system. This could occur in situations where network conditions, such as overloads or failures, could lead to equipment damage or operational failure.

When such threats are identified, immediate action is necessary to prevent escalated issues such as cascading failures or system outages. Disconnecting helps to ensure that the remaining portions of the grid remain operational and stable, thereby protecting both infrastructure and service to consumers.

Understanding this context also illuminates why the other scenarios do not meet the criteria for disconnection. Routine maintenance typically involves planned outages that are managed and coordinated with minimal disruption. Excessive demand can often be addressed through load management or demand response measures rather than disconnection. Lastly, disconnection due to generation capacity exceeding needs is generally managed through curtailment strategies rather than disconnecting entirely, as the grid aims to optimize resources efficiently without compromising reliability.