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RAM Terms and Definitions
C-2
The above equations adhere to IEEE Standard 762: Standard Definitions for use in Reporting Electric Generating
Units Reliability, Availability, and Productivity
Unavailability Types
SPS ORAP
®
System
IEEE 762 Equivalent (1987)
Forced Outage Types
FOA
Forced Outage - Automatic Trip: While the unit was
operating a component failure or other condition
occurred which caused the unit to be shut down
automatically by the control system
.
Unplanned Outage (UO)
UO Class 1
FOM
Forced Outage - Manual Shutdown: While the unit was
operating a component failure or other condition
occurred which resulted in a decision by the appropriate
person (or persons) to manually trip the unit from
service.
Unplanned Outage (UO)
UO Class 1
UO Class 2
UO Class 3
FS
Failure to Start: A signal was given to start the unit but
the starting sequence was not fully completed (unit did
not synchronize with system) within the required time
period. Sequential failures to start caused by a single
problem are to be counted as one failure to start event,
unless corrective action is performed or a successful start
is achieved in the interim.
Unplanned Outage (UO)
UO Class 0
FU
Forced Unavailability:
1. The unit was available in the Reserve Shutdown
(standby) state, but a component failure or other
condition caused it to be reclassified as "Unavailable".
2. An extension of a planned maintenance action due to
additional component failure/repair.
Unplanned Outage (UO)
UO Class 1
Scheduled Outage Types
MU
Maintenance - Unscheduled: Maintenance that is
required, but has not been specified in the maintenance
plan. This outage type can be a result of a unit shutdown
(when the unit is not required or outage time has been
scheduled) to facilitate repairs to the unit.
Unplanned Outage (UO)
UO Class 4
MS
Maintenance - Scheduled: Maintenance that is pre-
planned, well in advance of the outage, as part of the
maintenance plan.
Planned Outage (PO)
Other Outage Types
DR
Derating: A component failure or limitation causes a
decrease in the output of the unit.
Planned Derating
Unplanned Derating
NC
Non-Curtailing Event - A redundant component fails, but
does not impact the intended operation of the equipment.
(No outage code exists in
IEEE Std. 762)
CM
Concurrent Maintenance: Maintenance is performed
while downtime is charged to another component or
while the unit is operating on-line or is available to start
off-line (in reserve shutdown).
(No outage code exists in
IEEE Std. 762)