state in which a portion of the utility grid, containing load and generated electric power, continues to operate isolated from the rest of the utility grid
NOTE 1 The generated electric power and the load in an island may be any combination of customer-owned and utility-owned
a) intentional island
island that is intentionally created, usually to restore or maintain generation of electricity in to a section of the utility grid affected by a fault
NOTE 2 An intentional island includes an agreement between the controlling utility and the operators of customer-owned generation
b) unintentional island
island in which the generation of electricity within the island that is supposed to shut down continues to operate
c) run-on
amount of time that an unintentional island exists
NOTE 3 “Run-on” is defined as the interval between the start of an abnormal condition on the distribution system and the time when the distributed generator ceases to energize the distribution system
NOTE 4 The time represented by run-on is also referred to as "trip time" |