The development of smart substation is promoting and improving the integration of devices. The requirements of the integrated device of merging unit and intelligent terminal are discussed as are the advantages

such as reducing device quantity and network equipment investment

and saving cabinet space. Three technology schemes of integrated devices are presented and the recommended integration scheme is given and analyzed. The key technological problems involved by the integrated devices are treated

including the share of the same network port of sampling value (SV) and generic object-oriented substation event (GOOSE)

the resource integration of CPU

the integration of synchronization and maintenance platen

the power supply

and the man-machine interface. Problems such as the applied voltage classes

the port improvement of protection devices

the transmission of network

and the maintenance are presented.