Product Description:

The RAC 3.5-100-460-A0I-W1-220 is an AC main spindle drive controller designed by Bosch Rexroth Indramat for the RAC Spindle Drive Controllers series. As a closed-loop power stage, it governs the speed and torque of high-performance machine-tool spindles by converting three-phase mains power into a regulated output that follows command signals from the CNC. Within a machining center, the unit links the numerical control to an induction or synchronous spindle motor, enabling rapid acceleration, controlled braking, and stable speed holding over extended duty cycles. This operating role helps the spindle remain responsive during changing cutting loads without requiring a separate external regulation stage.

The power section accepts a three-phase supply of 3 x AC 400 V, 50 Hz, +/-15% or an alternative feed of 3 x AC 460 V, allowing the same frame to serve both European and North American plants. Control logic is isolated from the main bus and is energized by AC 230 V / 50-60 Hz, which helps protect signal circuits from line disturbances. At full load, the inverter can deliver a continuous phase current of 100 A, providing the current needed for demanding spindle starts and sustained operation under load. Heat generated by the power semiconductors is removed by an internal blower, so external ducting is not required and cabinet layout remains straightforward.

Command and feedback paths follow a purely analog architecture. The velocity setpoint arrives as an analog (+/- 10 V) signal that the drive converts into torque-producing current with a fast response, making it suitable for CNC systems that use voltage-based spindle commands. For position-loop closure at the CNC, an incremental encoder output is forwarded through connector X4, 9 poles. No second measuring system is fitted, so the unit is supplied without an additional bleeder resistor and without an extra encoder input, which keeps the wiring arrangement simpler. Internally, the unit is classified as series 3 and version 5.