Product Description:

The RAC 3.5-200-460-L00-Z1-220 is an AC main spindle drive controller manufactured by Bosch Rexroth Indramat as part of the RAC Spindle Drive Controllers series. In a machining center, it converts fixed-frequency plant power into variable-frequency, high-current output so the spindle can start, stop, and reverse under program control. By handling both velocity loops and dynamic braking functions inside one chassis, the unit simplifies cabinet wiring and supports coordinated motion during demanding metal-cutting operations. That modulation lets the spindle maintain commanded speed through tool engagement, rapid reversals, and programmed speed changes across a machining cycle. This arrangement also helps the drive respond consistently when cutting loads change quickly.

An integrated additional bleeder absorbs regenerative energy during rapid deceleration, helping protect the intermediate circuit from overvoltage. The controller is supplied without an additional encoder input, so feedback is expected through the primary spindle encoder rather than a separate secondary channel. Thermal dissipation is managed by internal blower cooling, meaning a built-in fan moves air across the heat sinks without external ducting. Drive-to-control communication uses X4 optical waveguides, which carry fiber-optic signals that are resistant to electromagnetic noise. Using fiber links also reduces susceptibility to electrical interference near motor leads and braking circuits. The power stage can supply a continuous spindle current of 200 A, allowing high torque at low speed during tapping, threading, and heavy roughing cycles.

The control logic is energized from a separate AC 230 V supply at 50 to 60 Hz, which helps isolate sensitive electronics from line transients in the power section. Main power can be connected to 3 x AC 400 V three-phase mains with a tolerance of ±15%, or to 3 x AC 460 V mains. This split between control power and the main input separates low-power electronics from the large current demands of spindle operation. Spindle speed references arrive through the SERCOS interface, which provides deterministic cyclic data for coordinated multi-axis motion. The unit is series 3 and version 5.