If a Balancing Authority is unable to calculate ACE for more than _____, it shall notify its Reliability Coordinator.

• A. 15 minutes
• B. 30 minutes
• C. 1 hour
• D. 2 hours

Answer: (B)

ACE shows how closely a Balancing Authority is keeping its actual net interchange in line with its schedule, after accounting for frequency deviations. When a BA can’t calculate ACE, it loses visibility into its real-time imbalance and can’t confirm it’s meeting reliability limits. The standard designates a 30-minute threshold: if ACE can’t be calculated for more than 30 minutes, the BA must notify its Reliability Coordinator. This keeps RC informed so they can coordinate responses, adjust operating plans, or take mitigations to maintain reliability while the data issue is addressed. Thirty minutes is short enough to preserve situational awareness and long enough to accommodate temporary data problems; shorter windows could cause overreaction from frequent alerts, while longer ones would delay awareness of an emerging imbalance.