en Railway Transportation Railway Transportation پژوهشي Research <div style="text-align: justify;"><span style="font-size:11pt"><span style="text-justify:kashida"><span style="text-kashida:0%"><span style="line-height:normal"><span style="font-family:Calibri,sans-serif"><span style="font-size:10.0pt"><span style="font-family:&quot;Times New Roman&quot;,serif">This paper investigates the performance of a medium-voltage hybrid circuit breaker designed for the protection of electrical power supply networks in railway transportation systems. Two primary topologies, namely LCS (Load Commutation Switch) and CCDC (Current Commutation Drive Circuit), are analyzed for AC and DC networks, respectively. Leveraging recent advancements in semiconductor technology and power electronics, novel approaches are introduced to enhance efficiency and reduce fault-clearing times. The performance of hybrid circuit breakers in medium-voltage AC and DC networks is evaluated using LTspice and PSpice simulation environments. The results demonstrate that the proposed hybrid circuit breaker achieves efficient fault protection with fault-clearing times of less than 10 milliseconds, outperforming conventional systems. Given the critical importance of protection in railway electrical power supply networks, this study proposes enhancements in protective characteristics, particularly in fault-clearing speed, through the application of hybrid circuit breakers.</span></span></span></span></span></span></span></div> High-Speed Circuit Breaker, Hybrid Circuit Breaker, CCDC Topology , LCS Topology 81 98 http://ijrare.iust.ac.ir/browse.php?a_code=A-10-281-2&slc_lang=en&sid=1 Ahmad Olyaei 180031947532846002966 180031947532846002966 Yes School of Railway Engineering, Iran University of Science and Technology, Tehran, Iran Rozbeh Asad 180031947532846002967 180031947532846002967 No School of Railway Engineering, Iran University of Science and Technology, Tehran, Iran