An indoor high voltage vacuum circuit breaker (VCB) is a critical protection device designed for safe interruption of high currents (up to 52 kV) in indoor electrical systems. Utilizing vacuum interrupters within sealed chambers, it extinguishes arcs rapidly during fault conditions, ensuring reliable short-circuit and overload protection. Its compact, maintenance-free design suits confined spaces like substations, industrial plants, and commercial buildings. Key features include robust insulation (epoxy resin or ceramic), motorized or spring-operated mechanisms, and compatibility with smart grid monitoring systems. Compared to SF₆-based breakers, VCBs offer eco-friendly operation, reduced fire risk, and compliance with IEC 62271 standards. Ideal for frequent switching, they enhance grid stability, safety, and energy efficiency in modern power distribution networks.