A Methodology For Assessing The Inuence Of Instrument Transformer Characteristics On Power System Protection Performance

Abstract- This paper presents a new methodology for evaluation of the inuence of instrument transformers (ITs) on performance of protection system. Instrument transform-ers are responsible for delivering accurate power system cur-rent and voltage replicas to protective relays. However, both theoretical research and eld application have shown that, due to their characteristics, conventional ITs may degrade relay performance signicantly. So far, various studies in-vestigated many aspects of the mentioned inuence. The methodology presented in this paper takes systematic ap-proach to the problem: it examines possible criteria and de-nes procedure for evaluation of the inuence. An applica-tion of the methodology is presented, along with the results. Suggestions for the improvement of application of conven-tional instrument transformers are also given