Technology Innovation and Evolution in Circuit Protection

Significant improvement in performance has been made over the past decades for circuit breakers due to advancement of arcing contact science, material science, and electronic technology. Two key R&D areas are interruption capability and digitization. Physical phenomena and design parameters that affect arc interruption includes arc chamber material outgassing, contact materials and post-arc current phenomena. If not properly designed, they often lead to re-ignition after current zero, resulting in failed short circuit interruption. Understanding of these phenomena and their impact on arc interruption is critical for circuit breaker development and design.More recently, driven by energy transition and future power grid needs, significant investigation and study has been made in solid state and hybrid circuit breaker technology for DC applications. This type of circuit breakers can interrupt a short circuit event within tens or hundreds of microseconds instead of milliseconds or tens of milliseconds by electromechanical circuit breakers. They enable circuit protection with bi-directional current flow, remote controllability, and software-defined functionality.This paper will highlight some of the technology development work on circuit breaker by the author and his colleagues over three decades. Meanwhile it will provide an overview of needs and emerging technologies for future circuit protection.