Product Description:

The RAC 2.2-250-460-A0I-Z1 is an AC main spindle drive controller from Bosch Rexroth Indramat in the RAC Spindle Drive Controllers series. It commands three-phase spindle motors used in CNC machining centers and other automated equipment, converting velocity references from the numerical control into controlled current and voltage at the motor. As the central power stage for the spindle axis, the unit combines gating electronics, protection circuits, and cooling hardware in one housing so the automation cabinet can be kept compact. It is intended for spindle applications that need regulated torque at low speed and stable speed holding across the operating range. This arrangement also supports consistent spindle response during speed changes, cutting loads, and repeated start-stop cycles.

The drive accepts a three-phase supply of 3 x AC 400 V, 50 Hz, ±15%, or 3 x AC 460 V, allowing installation on both IEC and NEMA power networks. During continuous operation, it can deliver 250 A to the motor inverter bridge, providing the current needed for high spindle acceleration and heavy cutting duty. Thermal energy created by the switching elements is removed by an internal blower, so only filtered ambient air is needed for cooling. Velocity commands arrive through an analog (±10 V) differential input, and user wiring, including enable signals and tachometer lines, is landed on the X4 9-pole terminal block. The differential command interface allows the CNC to vary spindle speed and reverse direction with a continuous reference signal.

The unit is series 2 and is designated Version 2. For rapid deceleration events, the controller is fitted with an additional bleeder, so surplus DC-bus energy is dissipated safely inside a guarded resistor bank. Encoder information can be forwarded to supervisory drives through the incremental encoder output. The base unit is supplied without an additional encoder input, which suits applications that use a single feedback source for the spindle axis. This layout keeps the feedback path straightforward when a second encoder channel is not required.