The Electric Power Research Institute initiated research into design concepts and architecture for an integrated system that can perform all the relaying and control functions for electric power substations. The resulting development work has focused on replacement of the host of individual relays and control devices, and all the interconnecting wiring, with a network of microprocessors connected by digital data communications channels. Optical fibers are the principal communications medium. The end objective is to achieve substantial construction cost and time savings, while providing improved performance of functions, and some entirely new capabilities. The authors briefly present the overall design concepts and features, summarize the test phase, and discuss the status of the Westinghouse Substation Protection and Control system, which has resulted from this research. Results of a trial installation have confirmed the anticipated benefits. >