Feeder Protection Relay REF 610 - APE Distribuidor ABB

Feeder Protection RelayREF 610Fig. 3 Substation feeder O/C and E/F protection, and substation busbar protection based onRE_ 610 series protection relays. The operate time of the busbar protection has beenspeeded up using the principle of upstream interlockingThe connection of the CTs to the REF 610relay depends on the available number andtypes of CTs in the feeder cubicle. Generallyan outgoing feeder is equipped with threephase current transformers for high- andlow-set overcurrent protection. The residualcurrent for the earth-fault protection can bederived from the three phase currents. It canalso be measured with a ring-type cable currenttransformer, should the outgoing feederbe a cable line and a sensitive earth-faultprotection be required.Should the feeder cubicle be equipped withtwo phase current transformers, the REF 610relay can still be used for high- and low-setovercurrent protection including phase discontinuityand phase unbalance protection.ABB