What is the required recovery timeframe for ACE if it's less than 80% of the MSSC?

The required recovery timeframe for the Actual Control Error (ACE) being less than 80% of the Maximum Sustainable System Capacity (MSSC) is set at 30 minutes. This timeframe is critical within the context of maintaining system reliability and performance standards under the North American Electric Reliability Corporation (NERC) guidelines.

When ACE is below this threshold, it indicates a potential imbalance in the system that could affect overall reliability. The 30-minute recovery period allows operators to quickly implement corrective actions to bring the ACE back within an acceptable range. This prompt response is essential for mitigating risks of larger disturbances or cascading failures in the electric grid.

In operational terms, having a defined timeframe such as 30 minutes provides clarity for operators on the urgency needed when system performance does not align with predetermined standards. It fosters a proactive approach to system management, ensuring that timely response measures can be put in place to secure the operational integrity of the transmission grid.