What Is Event Analysis:

Through the Event Analysis Process (EAP), entities voluntarily work with NERC and their Regional Entities to review events on the BPS. The EAP provides a consistent approach to event analysis and a platform for sharing lessons learned with the industry. All lessons learned through the EAP are posted on the NERC website.

Loss of Bulk Electric System (BES) facilities (Category 1a): Unintended loss of three or more facilities from a common cause.

Remedial Action Scheme (RAS) misoperations (Category 1c): Failure or misoperations of a RAS.

System voltage reduction (Category 1d): System-wide voltage reduction of ≥ 3 percent for 15 minutes or more due to a BES emergency.

Islanding (Category 1e): Unintentional BES separation resulting in an electrical island ≥ 100 MW.

Loss of monitoring or control (Category 1h and 2b): Loss of monitoring or control capability for 30 minutes or more that affects an entity’s ability to make operating decisions.

Loss of load (Category 2f and 3a): Loss of firm load for 15 minutes or more exceeding 300 MW for entities with previous year's demand ≥ 3,000 MW, or 200 MW for all other entities; or the unintended loss of ≥ 2,000 MW of generation.

Page Tips:

In this section of the report, the information is not shown by region or BA. This section shows how the Western Interconnection is doing overall, so the map and regional functions are not present. However, in this section, the use of statistical significance is introduced.

The chart on the right shows the historical data that is selected by the filters and a trend line over the last five years. The summary box shows the change per year, a p-value (a statistical measure showing the significance of the trend), and a flag that shows whether something is significant.