What is the maximum duration a Transmission Operator can take to return the transmission system to within IROL?

The correct duration for a Transmission Operator to restore the transmission system to within the Interconnection Reliability Operating Limits (IROL) is indeed 30 minutes. This timeframe is critical as it helps ensure that the system maintains its reliability during abnormal conditions.

When a system operates outside of its IROL, it indicates a level of stress that could potentially lead to widespread reliability issues, including cascading outages. The 30-minute window provides operators with sufficient time to assess the situation, implement corrective actions, and make informed decisions to stabilize the system without compromising safety or reliability. This time limit is established to balance operational flexibility with the need for proactive management of system integrity.

This duration is tied to NERC standards, which emphasize the importance of timely actions to prevent further degradation of system conditions that could result from delayed response.