The development of the communication technology makes it possible of integrating the sampled value (SV) network, generic object oriented substation events (GOOSE) network and manufacturing message specification (MMS) network for the bay level, the process level, and the station level (three-level-in-one-network). A new developed protective device for this integration can realize the grading and separate treatment of the network data. Meanwhile, this new device can network with the corresponding switch, which can solve the data synchronization problem under the three-level-in-one-network condition, thus the problem of the data reliability and availability of the protective device can be solved. Under the three-level-in-one-network structure, this device can meet the requirements of protection and control in the smart substation. The reliability of this new developed protective device already has been verified by relevant tests.