IEEE 859:2018 pdf free download – IEEE Standard Terms for Reporting and Analyzing Outage Occurrencesand Outage States of Electrical Transmission Facilities
NOTE—In general, a component-based system of outage data collection for a system will be basedon an inventory of components (the “population”) which is intended to be exhaustive cvery.relevant portion of thesystem is a part of oneand only onecomponent. A comprehensive inventory.of subcomponents is not usually developed, although an inventory of a particular class or category.of subcomponents may be developed to support a particular study.Performance indices such as.failure rate are systematically calculated for all components in therelevant population but are rarely.calculated for subcomponcnts.Examples include: line sggments，towers， and buses might besubcomponents of a line section; bushing, tank， and winding might be subcomponents of atransformer.
3.2.1 Line segment
A portion of a line section that has a particular type of construction or is exposed to a particular typeof failure, and therefore which may be regarded as a single entity for the purpose of reporting andanalyzing failure and exposure data.
NOTE-A line segment is a subcomponent of a line section.
3.3 Unit
A group of components that which are functionally related and are regarded as an entity forpurposes of recording and analyzing data on outage occurrences.
NOTE 1-A unit can be defined in a number of ways. For example, it may be (1) A group ofcomponents that which constitute an operating entity bounded by automatic fault interruptingdevices which isolate it from other sudh entities for faults on any component within the group;(2)Agroupof components protected by and within the sensing zone of a particular system of protectiverelays. Examples include a transformer or an overhead line and associated terminal facilitiesswitched with it;(3) A group of components including a transmission line, oneor more tran sformerssupplied by the line, and a subtransmission or distribution network radially supplied from thetransformer. These components are so configured that the subtransmission network is in the outagestate during outage occurrences of the transmission line.
4.5.2 Failure of response function
The inability of a component to perform a function that is which is required as a response to systemconditions or to a manually or automatically initiated command.
NOTE一Response functions include responding to fault conditions (protective systems)，tocommand (circuit breakers), and to manual operation (disconnect switches). Inabilities to perform aresponse function do not cause an immediate interruption of power flow as they can be disclosed bysubsequent inspection or by failure to respond to conditions as intended. This type of failure hasbeen referred to as dormant failure, latent failure, and unrevealed failure. Examples are switchingequipment failing to open on command, switching equipment failing to close on command, andprotection system tripped incorrectly (over-reach during fault).
5.4 Outage duration
The period from theinitiation of an outage occurrence until the component or unit is returned to thein-service state.
NOTE 1-Outagedurations are commonly summarized for specific types of outages as, for example,permanent forced outage duration，transient forced outage duration,and scheduled outageduration.(See 7.2.2)
NOTE 2-Outage duration is normally equal to the sum of switching time, repair time, and traveland material procurement time,but may be longer for reasons other than unavailability ofmanpower, equipment, or material.
6. Exposure parameters
Exposure in this context means vulnerability to hazards that which can cause outage occurrences.Enumeration of all design characteristics affecting such vulnerability is beyond the scope of thisstandard. Some examples are:. length of line, use of common structure, common right-of-way,common coition terminal(s), application of shielding, or localized hazards. However, it is generallyunderstood that the expected number of outages or failures increases with time, or commands tooperate, or both. What measure of exposure is relevant depends on the failure mode.
NOTE 1—Exposure parameters may be aggregated for purposes of calculating average outageindices of a class or population of components or indices.