Failure Modes and Mechanisms Working Group

The Failure Modes and Mechanisms Working Group (FMMWG) is an offshoot of the Event Analysis Subcommittee (EAS), which reviews power system disturbances for trends and lessons learned. The FMMWG was formed specifically to examine the record of station equipment failures during the aforementioned disturbances, which often showed common causes. 

The FMMWG has produced over two dozen diagrams for a variety of equipment types, including circuit breakers, communications equipment, relays, instrument transformers, and other substation equipment. Diagrams for wind and conventional generation freeze-protection followed the winter storm events.  Another dozen diagrams are also in the works, for static var compensators, battery chargers, uninterruptible power supplies, batteries and even more mundane items like conductors and supporting structures. The most recent products cover inverter equipment, both for solar and high-voltage DC applications. 

NERC’s Rick Hackman, who facilitates the group, describes the Failure Modes and Mechanisms (FMM) approach as a technique used to identify and map the signatures and paths of equipment failures. The approach consists of observing a signature to which something happened to the normal operating state of the equipment and identifying the specific physical path to failure of the equipment. Put more simply, a “failure mode” gets your attention that the equipment is not in a ​normal state, and a “failure mechanism” is the catalyst and physical path to failure.

The FMMWG is just one of many groups working to support electric reliability through raising awareness of important issues facing the industry. For more information NERC has a short video explaining the approach of the FMMWG.