Reliability & N-1 Contingency Analysis

Method & Assumptions

Component availability is computed from Mean Time Between Failures (MTBF) and Mean Time To Repair (MTTR) values per IEEE Std 493 (Gold Book) and IEEE Std 1366:

A = MTBF / (MTBF + MTTR)

Expected outage hours per year per component:

downtime = (8760 / MTBF) × MTTR

System unavailability is computed using minimal cut sets up to N-2 failure combinations. Components are loaded from the active One-Line Diagram. Set MTBF and MTTR values on each component in the One-Line editor to enable analysis.

Connector elements (cables, feeders, links) are excluded from the component count — they contribute to path unavailability rather than as standalone components.

References: IEEE Std 493-2007, IEEE Std 1366-2012, IEC 60300-3-2.

Component Override Values

Leave blank to use values stored on the One-Line component. Overrides here are applied only for this analysis session.

Click Load from One-Line to populate component list.