The Protective Relaying Control Station is a standard 48 cm (19 in) rack, mounted on castors, that forms the basis of a typical protective relaying control station. Two sets of dc control relays, a dc power supply, and an interconnection panel are mounted on the rack.

The two sets of dc control relays (six relays per set) allow basic contacts of protective relays (either normally open or normally closed contacts) to be converted into multiple normally open (NO) / normally closed (NC) contacts to actuate ac circuit breakers (contactors) in the electrical power system. Two of the dc control relays have adjustable time delay. The dc power supply is used to energize the relay coils.

The interconnection panel consists of three sets of twelve 4 mm safety banana jacks mounted on a standard 48 cm (19 in) panel. Three multiple contact connectors, also mounted on the panel, allow connection of cables from the Interconnection Module, Model 3787.

A set of metal rails and three standard 48 cm (19 in) blank panels are supplied with the Protective Relaying Control Station. The metal rails are used to mount the protective relays in the control station. Customers can use the three blank panels for mounting their own protective relays in the control station.