Abstract: Taking into account the characteristics of bus, a finitely concentrated outdoor installation bus protection consisting of the basic protection system and several extended protection systems, respectively is proposed, with the functions of the basic protection system and expanded protection described, respectively. With refererence to typical engineering designs, the optimal unit number of access intervals each of the protection system is demonstrated. The basic means of communication between the protection system and extended protection system and message transmission mechanism is expounded, the principle of synchronous sampling pulse based on PPS is put forward, the plug and play interface based on the definition by standard port design with aerial plug is discussed. the device was given the station control layer communication interface definition, process substation interface definition, the appearance of the map and navigation device inserted diagram. Finally, the finitely concentrated distributed engineering configuration of bus protection scheme on the engineering site is listed.