The ZN85C-40.5 handheld indoor high-voltage vacuum circuit breaker is an innovative switchgear designed specifically for 40.5kV indoor distribution systems. It adopts a handheld modular design and combines vacuum arc extinguishing technology, with a short-circuit current breaking capacity of up to 40kA. The handcart structure supports quick insertion and removal operations, increasing maintenance efficiency by 60%. It is compatible with KYN series switchgear and complies with GB/T 1984 and IEC 62271-100 standards. With a mechanical lifespan of over 10000 cycles and a protection level of IP4X, it is suitable for high-frequency operation scenarios in substations, industrial and mining power distribution, and data centers, providing a "flexible and portable, zero SF6 emission" green power protection solution.