Product Description:

The KDA 3.3-100-3-API-U1 is a spindle drive produced by Bosch Rexroth Indramat within the KDA Spindle Drives series. It acts as the power stage between a common DC bus and a machine tool spindle motor. The unit converts constant bus voltage into a regulated three-phase output that follows commands from the numerical controller. In automated machining cells, it maintains spindle velocity accuracy, exchanges position information with feedback devices, and removes switching losses through an integrated blower and heat sink assembly. This arrangement allows the spindle to respond smoothly to commanded speed changes during drilling, milling, and other continuous cutting processes.

The power electronics are sized for a continuous motor phase current of 100 A and are supplied from a stabilized bus voltage of 300 VDC. Spindle speed is set with an analog reference, so the controller can modulate output in proportion to a ±10 V signal. Thermal energy is removed by a mounted heat sink blower that operates in forced cooling mode. The blower is powered from a dedicated 115 V/50–60 Hz AC tap, which keeps airflow independent of spindle speed and helps limit heat buildup in the drive electronics during low-speed machining.

For shop-floor installation, the drive operates in ambient temperatures from 5 to 45 °C without current derating and can be mounted up to 1000 m above sea level while keeping bus capacitors within voltage tolerance. The logic board is version 3, which matches the Series 3 designation in the type code. A built-in diagnostic port retransmits speed and position data through an incremental encoder output, allowing external monitoring devices to share the same feedback stream used by the control loop. This output can also be used by external displays or supervisory devices that need live motion data. A second encoder socket is also provided so the drive can accept spindle feedback or additional motor feedback without added signal conversion delay.