Product Description:

The RD51.1-5B-018-L-DF-FW is manufactured by Bosch Rexroth Indramat and belongs to the RD 500 Drive Controllers series. The unit converts fixed-frequency mains energy into a variable output that lets induction motors match process requirements in automated lines, conveyors, and similar equipment. By adjusting voltage and frequency simultaneously, it provides basic speed regulation without encoder feedback, making it suitable for general industrial applications where precise servo behavior is unnecessary. This operating principle supports steady motor control in equipment that does not require closed-loop position feedback.

This model delivers a continuous output of 18.5 kW, giving it enough headroom for medium-power pumps, fans, and processing machinery. It is designed for grids that supply up to 500 V and uses a three-phase AC converter input section to rectify and re-synthesize the drive waveform. Motor excitation follows U/f curve control; voltage rises proportionally with frequency so magnetic flux stays near nominal throughout the operating band. Internal heat is removed by forced air cooling, and airflow is guided through finned heat sinks to keep semiconductor junction temperatures within limits during sustained operation. Dynamic regeneration is handled by a built-in brake chopper, which diverts surplus DC-bus energy into an external resistor during rapid deceleration.

An integrated I/O board provides a NAMUR terminal strip with external 24 V standby power, so field sensors can remain energized when the main converter is disabled. For diagnostic and protection purposes, the control section returns current filter feedback (U6, V6, W6), allowing supervisory electronics to monitor phase balance and filter behavior during operation. The device is design generation 1, and its modular control software is ordered separately so the drive can be matched to the intended control setup.