Reliance solely on under/over volta

Reliance solely on under/over voltage and frequency trip is not considered sufficient to detect and cease to energize and trip. IEEE Std 1547.2™ [B18] may provide additional guidance on unintentional island mitigation, and additional equipment (e.g., transfer trip) may be necessary.To achieve coordination between unintentional islanding detection and automatic reclosing, auto-reclose times longer than 2 s may be considered in some circumstances.It is important to bear in mind that islanding detection methods in inverters are generally designed to detect islands with a generation-load balance. They are not intended or designed to detect faults and should not be relied upon for that purpose.Also called “Facility Island,” see Annex C.