Product Description:

The RD51.1-4N-055-L-NN-FW is a three-phase AC drive controller produced by Bosch Rexroth Indramat for the RD 500 Drive Controllers series. Positioned between the mains supply and an induction motor, it modulates voltage and frequency so automated conveyors, mixers, or pumps run at the required speed for each process stage. By shaping the output waveform, the unit helps match motor torque to load demand and limit mechanical stress during acceleration and deceleration. This type of control supports processes that need adjustable motor speed without changing the connected machine layout.

The controller is built as a 3 × AC converter, meaning it rectifies and inverts all three incoming phases rather than drawing from a single phase. It accepts line potentials from 380 to 480 V, making it compatible with common industrial low-voltage networks. Input swings of up to ±10% are tolerated without a fault shutdown, which helps the drive remain operational during normal supply variation. The inverter supplies 55 kW of mechanical power, which is suitable for medium-size motor loads in material-handling and process equipment. Speed regulation uses U/f curve control, so stator voltage rises in proportion to frequency to help maintain magnetic flux at lower speeds. This control method is well suited to variable-speed applications that do not require encoder-based servo operation.

Thermal management relies on forced air cooling, with cabinet airflow guided across the heat sink to remove switching losses. An integrated mains filter suppresses conducted electromagnetic interference, which reduces the need for external filtering in many installations. The power section is supplied without a built-in brake chopper, so applications that need dynamic braking require an external resistor module. The unit is built to design generation 1. Application features are available only after the required software package is ordered separately, allowing the drive to be matched to the intended fieldbus or functional package.