Product Description:

The RAC 3.5-150-460-A0S-W1-220 is an AC main spindle drive controller manufactured by Bosch Rexroth Indramat and assigned to the RAC Spindle Drive Controllers series. It occupies the power stage of a machining center, converting plant power into a regulated output that the numerical control interprets as spindle torque and speed. This arrangement enables rapid acceleration, constant surface-speed cutting, and programmed deceleration of high-speed motorized spindles, supporting milling, drilling, and grinding operations that demand repeatable spindle behavior. In CNC machine tools, stable spindle response helps maintain cut quality when the load changes during machining.

The controller accepts a mains supply of 3 x AC 400 V, 50 Hz, ±15% or 3 x AC 460 V, allowing deployment in European or North American facilities without a step-up transformer. Its output stage can furnish 150 A of three-phase current, matching the needs of medium and large frame spindle motors used in metal-cutting machines. Logic and gate-drive electronics draw power from a separate AC 230 V / 50–60 Hz connection, isolating control circuits from the high-power bus. Thermal energy produced by the power semiconductors is expelled by an internal blower, eliminating the need for external ducting or heat sinks. Parameter backup and diagnostic scripting are carried out through an RS-232-C serial interface. The unit is series 3 and version 5 in the RAC family.

Velocity reference arrives as an analog (±10 V) signal, allowing direct connection to conventional CNC speed outputs and other standard analog command sources. Command and status wiring terminate on the X4 9-pole connector, which groups enable lines and ready contacts. The drive is supplied without an additional bleeder, so braking energy must be routed through an external resistor or dissipated regeneratively by the spindle motor. It also ships without an additional encoder input, so position feedback relies on the base channel integrated in the device.