VS1-Series embedded pole type of drawout VCB. vacuum circuit breakers are applicable to 12kV, three-phase AC 50Hz indoor switchgear and can serve as protection and control units for industrial and mining establishment transformer substation equipment. With modular and independent-frame design for their spring operating mechanisms, VS1-Series circuit breakers can operate with KYN28-12(24) mid-set and fixed switchgear. These circuit breakers are subject to both fixed installation and assembly with truck as a handcart unit