Product Description:

The RAC 4.1-300-460-AP0-W1 is an AC main spindle drive controller built by Bosch Rexroth Indramat within the RAC Spindle Drive Controllers series. The unit regulates three-phase spindle motors by supplying controlled current and voltage, allowing machine tools to keep commanded cutting speeds stable as spindle load changes during drilling, milling, or turning. Installed in a control cabinet, it links the CNC system to the spindle power stage and converts analog velocity commands into drive torque so speed response remains predictable during acceleration, deceleration, and steady-state machining.

The controller accepts a three-phase supply of 3 x AC 400 V, 50 Hz, ±15 % or 3 x AC 460 V, enabling direct connection to common industrial utility grids. Once energized, it can deliver a continuous output of 300 A, providing the current required by high-power spindle motors during sustained operation. Heat generated by the switching devices is removed by an internal blower, and the built-in fan moves air across the heat sink without external ducting. Speed references arrive as an analog differential signal of ± 10 V, which the control section converts into a proportional torque command. Field wiring terminates on connector X4 9 poles, where enable and status signals are grouped in one location for straightforward signal routing.

For position-synchronized machining, the drive includes an additional encoder input for spindle feedback that supports real-time phase alignment with axis drives. It also supports a high-resolution INDRAMAT encoder, allowing precise spindle feedback for rigid tapping, contour milling, and other coordinated operations. Because the DC link lacks an auxiliary resistor, the unit operates without an additional bleeder, so braking energy during rapid deceleration must be absorbed by the motor or returned to the supply. The controller is built as Series 4 hardware and is released as Version 1.