Product Description:

The RAC 2.3-250-460-API-W1 is an AC main spindle drive controller produced by Bosch Rexroth Indramat within the RAC Spindle Drive Controllers series. It modulates three-phase induction or synchronous spindle motors so that machining centers and grinding stations can hold commanded speeds under variable cutting loads. By processing analog speed references and high-resolution position feedback, the unit closes the velocity loop directly at the spindle and reduces the burden on the machine control for fast torque regulation.

This controller is designed for shop-floor power systems that supply 3 x AC 400 V, 50 Hz, ±15%, or 3 x AC 460 V. Under nominal conditions, the power stage can deliver up to 250 A of output current, making it suitable for high-inertia spindles that draw large acceleration surges. Thermal management is handled by a self-contained internal blower, so cabinet airflow does not need to be routed through the heat sink. The speed reference uses an industry-standard analog (±10 V) signal, allowing direct coupling with most CNC controls. For position synchronization during tapping or C-axis operation, the unit provides an additional encoder input for spindle feedback. This secondary channel lets the drive reconcile motor-mounted and machine-mounted encoder data without external interpolators.

The unit also provides an incremental encoder output that retransmits spindle position to downstream axes. It supports a high-resolution INDRAMAT encoder on the motor side to keep commutation error low at any speed. Wiring is concentrated on connector X4, 9 poles, so low-level signal routing remains organized through a single plug. The drive is supplied without an additional bleeder, and the remaining bus energy is handled by its internal resistor network to reduce panel footprint in compact machining centers.