Product Description:

The KDA 2.1-150-3-API-U1 belongs to the Bosch Rexroth Indramat KDA Spindle Drives series. As a spindle drive, it supplies controlled three-phase power to high-speed machining or grinding spindles and accepts speed references from the CNC in analog form. Within an automation cabinet, it works with a matching power supply to convert a fixed DC link voltage into a variable three-phase output that accelerates and brakes the motor according to program demand. Because the output frequency and voltage are regulated together, the unit can support spindle acceleration, steady cutting speed, and controlled deceleration within the same control stage.

The drive draws its DC bus energy from a 300 VDC supply and can deliver a continuous output of 150 A to the spindle windings. A dedicated auxiliary input rated at 115 V/50–60 Hz powers the heat sink blower so the main control electronics remain isolated from fan inrush current. Separating blower power from the DC bus also helps keep thermal management active whenever the unit is energized. The drive operates at ambient temperatures from 5 to 45 °C. Installation altitude is limited to 1000 m above sea level so reduced air density does not impair heat transfer. The internal regulator modulates pulse patterns to maintain spindle velocity within tight tolerances.

An incremental encoder output passes real-time spindle position to a downstream controller, while a separate second encoder input allows independent spindle feedback or additional motor feedback for tandem axes. That feedback arrangement lets the control system monitor actual shaft movement without relying only on commanded speed. Thermal management relies on a mounted heat sink blower that pushes air directly across the power semiconductors. This arrangement works with the drive’s forced cooling mode to keep semiconductor junction temperatures within the allowable range during heavy cutting cycles. The velocity reference reaches the control card through an analog speed command, enabling easy interfacing with legacy CNCs that output ±10 V tachometer signals.