Relay protection systems provide signals to operators, indicating emergency events and abnormal operating conditions, which assists in fault detection and restoration. What are the Benefits of Using RPA? Energy Efficiency. Replacement of aging components, implementation of innovative materials, and use of. Protective relays and devices have been developed over 100 years ago to provide “lastline”of defense for the electrical systems. The selection and applications of. This course explains how protective relays detect electrical faults and protect transformers, generators, motors, feeders, substations, and industrial power systems from abnormal operating conditions and equipment damage.