Which type of event typically triggers the requirement to file a formal disturbance report to NERC or the Regional Entity?

• A. Minor disturbances affecting BES reliability
• B. Routine maintenance events
• C. Major disturbances affecting BES reliability
• D. Public outages affecting BES reliability

Answer: (C)

Disturbance reporting is tied to how significantly an event affects the Bulk Electric System. The requirement to file a formal disturbance report is triggered by major disturbances that affect BES reliability. These are events that cause or could cause substantial impacts on transmission, generation, protection systems, or customer service, warranting formal analysis by NERC or the Regional Entity.

Minor disturbances that don’t threaten BES reliability aren’t subject to the formal disturbance report process, and routine maintenance events aren’t disturbances in this sense either. Public outages are reportable only if they rise to the level of a major disturbance affecting BES reliability. The purpose of the formal disturbance report is to capture detailed information about the event to support post‑event analysis and reliability improvements.