Indoor high voltage vacuum circuit-breaker of type VS1 (ZN63A) (briefly, circuit-breaker in the following) apply to 12 kV air insulated indoor switchgear, used as protection and control units for electric network, industrial and mining enterprise power equipments. Owing to the excellent performance, circuit-breakers are particularly suited to where frequent operations at rated current or multiple interruptions of short circuit current are required.

Integrated type design of operating mechanism and circuit-breaker proper is adopted in circuit-breaker, which may be used both as fixed installation unit and as truck unit fitted with special propelling mechanism.