Product Description:

The RAC 2.2-250-380-A0I-W1 is manufactured by Bosch Rexroth Indramat and belongs to the RAC Spindle Drive Controllers series. This unit supervises power conversion between a plant's three-phase mains supply and a machine-tool spindle motor. In a typical CNC cell, it processes velocity commands from the numerical control, delivers regulated current to the spindle windings, and monitors internal temperature through its integrated blower circuit. By combining motoring and regenerative braking functions, it helps maintain constant surface speed during cutting, drilling, or grinding cycles.

The controller is rated for 3 x AC 400 V, 50-60 Hz, so its intermediate circuit suits common shop supplies. Under that line voltage, it can furnish up to 250 A of output current, providing power for spindles used in heavy cutting. Thermal energy from this current is removed by a built-in fan, eliminating the need for external coolers and helping keep the housing within operating limits. Shaft speed is commanded through a ±10 V reference, and the electronics interpret this as an analog (±10 V) signal before translating it into pulse-width-modulated gate patterns for the power transistors. For feedback to the CNC, the unit provides an incremental encoder output that reproduces spindle position information for coordinated axis interpolation.

The control wiring is concentrated on the X4 9-pole connector, which allows the unit to be disconnected without disturbing the power cabling. The unit is an AC main spindle drive controller. In this second-generation design, it operates solely on its built-in braking resistor, so it is supplied without an additional bleeder. This version also ships without an additional encoder input, which simplifies the enclosure layout and keeps the available interfaces focused on the standard control and feedback connections.