The Okuma VAC Spindle Drives series is a family of variable-speed AC spindle drive units used in Okuma machine tools to regulate spindle motor speed and power within NC-based spindle systems.
The series combines a control section and a power section, and later VAC5 versions were offered in analog-interface and optical-interface forms so the drive could be matched to different command methods and earlier VAC system configurations. These drives are integrated with spindle motor power circuits, feedback devices such as pulse generators or magnetic encoder arrangements, resolver signals on applicable systems, cooling-fan circuits, and machine I/O and NC connections. The platform also includes front-panel status and diagnostic functions, with operating and fault indications used to monitor drive condition, charged main-circuit status, and abnormal operating states. Overall, the Okuma VAC Spindle Drives series is a machine-specific spindle control platform designed for coordinated spindle operation, compatibility across multiple Okuma system generations, and maintainability at the drive-unit level.
