Abstract:

The influence mechanism of narrow-slot structures on the critical current breaking capability in DC molded case circuit breakers is investigated. Using the control variable method, comparative experiments are designed for narrow-slot materials and spacing. An experimental platform is established in accordance with GB/T 14048.2—2020, and the critical load current of the prototype is determined through stepwise loading tests. Qualitative analysis and mechanism exploration are conducted based on experimental phenomena and data. From the dual perspectives of macroscopic energy evolution and the dynamic balance of “generation-extinction” of charged particles at the micro level, the experimental results are corroborated and mutually interpreted with arc extinction theory in multiple dimensions. The independent influence laws of narrow-slot material and spacing parameters on the critical current are clarified, providing insights into the reasons for difficulties in interrupting DC critical load currents and directions for improvement, as well as theoretical support for the refined design of arc-extinguishing systems in DC molded case circuit breakers.

Key words: direct current molded case circuit breaker, critical load current, narrow slit material, narrow-slot spacing