Product Description:

The RD51.1-5B-055-D-DL-FW drive controller is produced by Bosch Rexroth Indramat as part of the RD 500 Drive Controllers series. Designed for converter-based motor supplies, it manages asynchronous drives in material handling, pumping, and processing lines by modulating output frequency and voltage to reach speed and torque targets. It is intended for variable-speed operation where stable motor response is needed across changing load conditions.

Its continuous output is rated at 55 kW, so connected motors can draw that level of mechanical power when cabinet temperature stays within the allowed range. The unit is fed from a 500 V three-phase mains supply and uses an internal converter stage to generate variable voltage and frequency for the motor. Because control is executed with U/f curve control, the voltage-to-frequency ratio remains constant across the speed range, which helps maintain motor magnetizing current and prevents saturation at low speeds. Power enters through a Converter 3 × AC supply section that also charges the DC link, and the integrated built-in brake chopper diverts excess link energy to an external resistor during rapid deceleration.

Thermal management is handled by a plug-through cooler (≤ 110 kW) that extends the heat sink beyond the enclosure wall, allowing ambient air to remove transistor losses while helping keep the interior electronics isolated from dust. Control wiring terminates on a NAMUR terminal strip with external 24 V standby power, allowing emergency circuits to remain energized even when the main converter is disabled. For long motor leads, the drive includes cable damping feedback (C3, D3) so the regulator can compensate for resonant feeder effects. It is a design generation 1 module.