Transmission system protection: a reliability study

ConiEd developed a methodology for evaluating the reliability of transmission system protection schemes in 1995. Two approaches were developed; one focused on component reliability data, and the other on component operating history. The second approach has been put into practice. Review of disturbances identified protection schemes and lines that are less reliable than others, thus permitting a focused program of maintenance and replacements. The reliability method is described, along with sample data and results.