REF610 is a feeder IED for protection, measurement and supervision of utility and industrial distribution power systems REF610 is a member of ABB’ s Relion® product family and part of its 610 product series. The series includes protection relays for feeder protection, motor protection and general system voltage supervision. The plug-in design facilitates the commissioning of the switchgear and enables fast and safe insertion and withdrawal of protection relay plug-in units. REF610 is primarily intended for the protection of incoming and outgoing feeders in distribution substations of resistance earthed and solidly earthed power systems. REF610 is suitable for employment in marine and off-shore environments. Supplied with an optional arc protection function REF610 also provides fast substation busbar arc-fault protection.