Direct current circuit breaker primer

The growing need for electrical efficiency improvements, renewable resource integration, and safe, reliable power solutions have caused industries from nuclear to datacenters to reconsider DC (Direct Current) power throughout their facilities. Not only is there a growing trend towards DC power usage, but also as facilities get larger, there is a need for significantly higher DC interruption ratings. The industry is in a state of exploration of DC power and DC circuit breakers specifically. As industry reconsiders DC applications it is worth reviewing DC systems, equipment, and primary components such as DC circuit breakers. This paper serves as a primer for DC circuit breakers. A basic overview of DC power and DC applications will be presented in contrast with AC (Alternating Current) systems. The benefits of DC power applications, specifically the ease of integration of storage and renewable power resources, will be discussed. This paper also serves as a primer on the design of DC circuit breakers with a focus on interruption. The lack of a zero crossing requires circuit breaker designs to look beyond commonly used approaches in AC interruption and extend to new tools. Key interrupter systems are introduced and described. DC interruption approaches such as arc bending, arc blowing, extended arc runners, and arc chute design will also be discussed.