ABSTRACT
During the last 30 years, the substation automation (SA) has taken large strides. Earlier the control of substations was based on discrete electronic or electromechanical elements, and several functions were carried out separately by specific subsystems. The SA depends upon the interface between substation and its associated equipment to provide and maintain a high level of confidence demanded for the power system operation. Here each device has equal access to the communication bus and can also message any other device. This is substantially different from a master-slave environment. Experience indicates that over 50" of copper terminations, associated cost and labor, and potentialities for mistakes are eliminated. Ethernet over fiber is becoming the medium of choice where long distances are involved and immunity from electromagnetic interference is desired. The cost difference between copper and fiber cables is not much; however, the fiber Ethernet transceivers are more expensive.
