Product Description:

The RAC 2.3-250-380-A0S-W1 is produced by Bosch Rexroth Indramat and belongs to the RAC Spindle Drive Controllers series. It functions as the primary closed-loop unit that regulates induction or synchronous spindle motors on machining centers, maintaining the programmed cutting speed and torque profile during drilling, milling, and turning operations. By processing an external analog speed reference, the controller adjusts motor voltage and frequency so that spindle motion stays coordinated with axis drives and part programs throughout changing load conditions. This control behavior helps the spindle respond smoothly when the machining cycle shifts between acceleration, steady cutting, and controlled deceleration.

The unit is an AC Main Spindle Drive Controller in series 2 and version 3, intended for spindle applications that require regulated speed and torque. Its power section connects to a mains supply of 3 x AC 400 V, 50-60 Hz, so it can be integrated directly into standard three-phase plant distribution without a step-down transformer. The inverter section is rated for 250 A, indicating the maximum continuous motor current it can deliver before protective limiting is invoked under sustained load. Thermal energy generated by the switching devices is expelled by an internal blower, which helps keep the enclosure temperature within permissible limits in closed cabinets without separate external cooling equipment. Command input is accepted as an analog input of ±10 V, allowing the CNC, PLC, or motion card to set spindle speed with a proportional voltage signal rather than serial fieldbus traffic.

Parameter download and diagnostic messaging use an RS-232C serial interface, which provides direct access to setup data and status information. I/O and feedback wiring connect through the front-mounted 9-pole X4 connector, keeping the main control connections grouped at the front plate. The drive is supplied without an additional bleeder, so regenerated energy must be handled by the DC link of a companion unit or by mechanical damping at the motor during deceleration. It is also supplied without an additional encoder input, so position feedback relies on the primary spindle encoder routed through the main motor cable instead of a separate auxiliary channel.