Improved sensitivity and security for distribution bus and feeder relays

Traditional protective equipment does not adapt readily to distribution system reconfiguration. If new settings are needed they have to be manually changed: there are no settings in reserve. The time to make or enter and test new settings slows down emergency responses and risks human error. Sometimes relay settings are not changed for emergency or abnormal switching, because it takes too long or is too difficult. System protection is compromised. Multiple setting groups, negative-sequence overcurrent elements, alarm-directed backup, and time-overcurrent element reset options improve the fault detection sensitivity and system security provided by advanced microprocessor-based distribution bus and feeder relays.