Product Description:

The RAC 3.5-150-460-APS-Z1-220 is an AC main spindle drive controller produced by Bosch Rexroth Indramat for the RAC Spindle Drive Controllers series. Designed to regulate high-power machine-tool spindles, this unit converts three-phase input power into precisely controlled motor output so cutting, drilling, or grinding axes can hold programmed speed under changing load. It serves as the cabinet-mounted control stage between a CNC or PLC and the spindle motor, providing closed-loop velocity regulation and fast acceleration for continuous production cycles. The controller is intended for spindle applications where speed stability directly affects machining consistency during long operating periods.

The power section accepts 3 x AC 400 V or 3 x AC 460 V input within a ±15% tolerance and delivers up to 150 A of spindle current. Separate low-power electronics receive AC 230 V / 50-60 Hz, which helps isolate the control circuitry from the high-energy output stage. Commanded speed is set through a differential analog (±10 V) reference, allowing proportional velocity control from external motion processors while helping reduce the effect of electrical noise on the command signal. An internal blower moves air across the heat-sink fins so the converter can maintain rated current without relying on external cabinet fans.

An RS-232-C serial interface allows parameter access and fault interrogation from a host computer. A dedicated additional encoder input for spindle feedback receives signals from a high-resolution Indramat encoder so the controller can compare commanded and actual spindle speed in real time. Field wiring lands on connector X4 with 9 poles, which helps keep signal and power lines separated for better noise control. During regenerative braking, an additional bleeder resistor stage dissipates excess energy as heat instead of returning it to the DC link. The unit is series 3 and version 5.