Investigating DC circuit breaker service life

Abstract

This thesis investigates methods to extend the service life of DC circuit breakers using inductive voltage spike mitigation techniques aimed at reducing electric arcs during switching operations. Unlike AC systems, DC lacks a natural zero-crossing which results in large transient voltages that accelerate switch wear and reduce service life. A low-cost low-complexity RC circuit was designed using fundamental component equations and implemented in Simulink and in hardware revealing effective voltage spike reduction. Simulation predicted spike reduction from the megavolt range to approximately 110 V, while hardware results showed peak voltages reduced further to 40.1 V with strong repeatability. Switches were opened after further testing with and without the RC circuit active to show increased surface wear on the latter. Additional surge arresting MOV configurations were simulated at higher voltage levels, up to 500 kV. Findings demonstrate an effective and accessible method for improving DC system reliability.