IEEE 762:2006 pdf free download

IEEE 762:2006 pdf free download.IEEE Standard Definitions for Use in Reporting Electric Generating Unit Reliability, Availability, and Productivity.
4.1.2.2 Unplanned outage
The unplanned outage state is where a unit is unavailable, hut is not in the planned outage state.
NOTE 1—When an unplanned outage is initiated, the outage is classified according to one of five classes, as defined in 4.1.2.2.1.1 through 4.1.2.2.1.4 and 4.1.2.2.2.1 and 4.1.2.2.2.2. A Class 0 unplanned outage applies to a startup failure, and Class I applies to a condition requiring immediate outage. Also, an unplanned outage starts when a planned outage ends, but is cxtcndcd due to unplanned work. Class 2, Class 3, and maintenance outage apply to outages where some delay is possible in removing the unit from service. The class (2, 3, or maintenance) of outage is determined by the amount of delay that can be exercised in the removal of the unit. The class of outage is not made more urgent if the time of removal is advanced due to favorable conditions of system reserves or availability of replacement capacity for the predicted duration of the outage. However, an unplanned outage starts when the unit is removed from service or is declared unavailable when it is not in service.
NOTE 2—During the time the unit is in the unplanned outage state, the outage class is determined by the outage class that initiates the state.
NOTE 3—In some cases, the opportunity exists during unplanned outages to perform some of the repairs or maintenance that would have been performed during the next planned outage. If the additional work extends the outage beyond that required for the unplanned outage, the remaining outage should be reported as a planned outage.
4.1.2.2.1 Forced outage
A forced outage cannot be deferred beyond the end of the next weekend.
4.1.2.2.1.1 Class 0 unplanned outage (starting failure)
A Class 0 unplanned outage results from the unsuccessful attempt to place the unit in service (see 4.1.3.1).
4.1.2.2.1.2 Class I unplanned outage (immediate)
A Class 1 unplanned outage requires immediate removal from the existing state.
NOTE—A Class 1 unplanned outage can be initiated from either the in-service state or reserve shutdown state. A Class 1 unplanned outage can also be initiated from the planned outage state. See the note in 4.1.2.1.2.
4.1.2.2.1.3 Class 2 unplanned outage (delayed)
A Class 2 unplanned outage does not require immediate removal from the in-service state, but requires removal within 6 h.
4.1.2.2.1.4 Class 3 unplanned outage (postponed)
A Class 3 unplanned outage can be postponed beyond 6 h, but requires that a unit be removed from the in- service state before the end of the next weekend.
NOTE— -Class 2 and Class 3 can be initiated only from the in-service state.