Each Balancing Authority shall perform _____ error checks using Tie Line megawatt-hour meters with common time synchronization to determine the accuracy of its control equipment.

• A. daily
• B. weekly
• C. annually
• D. hourly

Answer: (D)

The main idea is that measurement accuracy for tie-line energy must be checked on the same hourly time basis that balancing and interchange operations use. Tie-line megawatt-hour meters capture the energy moving between Balancing Authorities, and using a common time reference ensures that the energy recorded for a specific hour in one BA lines up exactly with the corresponding hour in the neighboring system. By performing error checks hourly, the reliability system can detect and correct any drift, meter misreads, or timing errors before they affect the hourly energy balance, control actions, and interchange settlements. If checks were done less frequently, errors could go unnoticed for longer, leading to larger discrepancies within an hour and potential reliability or settlement issues. Therefore, hourly checks provide timely verification and maintain alignment of measurement data with real-time operations.