Product Description:

The RAC 2.2-250-460-API-W1 is an AC main spindle drive controller produced by Bosch Rexroth Indramat for the RAC Spindle Drive Controllers series. Within an automated machining center or grinding line, the unit regulates spindle torque and speed so that cutting surfaces stay within programmed limits. Its closed-loop structure works with a high-resolution INDRAMAT encoder to provide position feedback suitable for precision metal removal and related industrial tasks. This arrangement helps the spindle maintain commanded motion during changing cutting loads and low-speed machining steps.

This controller draws a rated current of 250 A and accepts three-phase power at 3 x AC 400 V and 50 Hz with a ±15% tolerance, or from a 3 x AC 460 V line. Speed reference arrives through a differential input that interprets analog (+/- 10 V) commands from the CNC. That input allows the drive to follow the speed demand generated by the machine control without a separate digital reference channel. Thermal loading is handled by an internal blower that circulates cabinet air across heat-generating components, eliminating the need for external ducting. The design omits an additional bleeder, so regenerative energy must be absorbed by the connected spindle or an upstream power module. A factory-installed additional encoder input accommodates spindle feedback signals, and the embedded encoder type is a high-resolution Indramat format that supports fine speed modulation near zero rpm. The additional encoder channel supports applications that need spindle feedback routed directly to the controller for stable speed regulation.

The drive is in Series 2, revision 2, and field wiring for command and status lines is consolidated on the X4 terminal strip with 9 poles. This keeps control and status wiring grouped at one connection point. For downstream control or diagnostic scopes, an incremental encoder output replicates the spindle position signal, permitting phase-locked auxiliary axes or trace recording without extra converters. That signal can be used by synchronized monitoring or external display equipment. The unit is supplied without an added brake resistor, so energy handling is provided in the machine design rather than in the controller housing.