A Bipolar Hybrid Circuit Breaker for Low-Voltage DC Circuits

Presently available dc breakers fall into three categories, mechanical, static, and hybrid dc breakers. With the advent of dc circuits, generation, and loads, dc breakers are required for system protection. This paper proposes a new alternate method to break dc currents for low-voltage applications. The proposed mechanism utilizes two switches along with two diodes, to reverse the direction of the current flow and clear the fault. This is different than the conventional single-switch commute-and-absorb method used in mechanical or static breakers in the sense that it reverses the current direction and delivers part of the fault energy back to the source. It is shown that the proposed method can break the fault current effectively with minimal arc and significantly reduces the voltage stress across the mechanical switches.