Product Description:

The VAC1-D8-A is a spindle-drive inverter produced by Okuma within the VAC Spindle Drives series. It regulates the speed and torque of high-speed machine-tool spindles, converting incoming AC power into controlled output for precise cutting, drilling, or grinding operations on CNC equipment. By integrating with Okuma control architectures, the unit supplies the dynamic acceleration and deceleration profiles required for modern metal-removal processes. Its control role is especially important in CNC systems where spindle speed must change quickly while remaining stable under varying cutting loads.

The power section accepts a wide mains window of AC 170-250 V at 50/60 Hz. The internal fan circuit uses the same line frequency, which simplifies supply wiring. Overcurrent protection is provided through a front-mounted No-Fuse Breaker, while six main input links are protected by 6 replaceable fuses. Command signals reach the drive through an analog interface that supports conventional spindle speed references from the numerical controller. Internally, one diode module rectifies the input, and six transistor modules generate the three-phase output waveform. Separate M5 terminals are assigned to both the motor and supply cables, allowing ring-lug connections with low contact resistance and keeping the main wiring path straightforward.

Thermal management is handled by a rear heat sink fan that draws air across the power semiconductors. The blower runs from a dedicated AC 200 V tap, so it remains active whenever the inverter is energized. Fan wiring lands on an M4 terminal block, isolating it from the heavier power conductors and keeping auxiliary connections separate from the main current path. Auxiliary protection is split between two fuse groups: the F1-F4 positions are rated at 5 A to guard low-voltage control circuits, while F5-F6 carry a 0.5 A rating for the feedback and sensor loops. The single diode pack and the six-pack transistor bridge are mounted directly to the heat sink, which helps keep junction temperatures within safe limits during continuous spindle duty.