Product Description:

The RD51.1-4N-075-D-NN-FW is a drive controller from Bosch Rexroth Indramat in the RD 500 Drive Controllers series. The device interfaces between a three-phase mains supply and an electric motor, delivering regulated voltage and frequency so the axis can follow commanded torque and speed references. In conveyors, mixers, and process pumps, it provides stable acceleration, steady-state speed, and controlled deceleration while helping protect the motor from supply fluctuations and mechanical overshoot. Its control stage adjusts motor output continuously as load conditions change, which helps maintain stable process behavior during starts, stops, and speed changes.

Rated output is 75 kW, which states the continuous mechanical power the connected motor can receive without the inverter exceeding its thermal limits. The permissible line window of 380 to 480 V allows installation on standard industrial low-voltage networks used in many regions. Incoming energy is processed through a three-phase AC converter topology, meaning the controller rectifies three-phase input power and reconstructs a variable AC waveform for the motor. Speed is modulated using U/f curve control; this open-loop method keeps the volts-per-hertz ratio constant so magnetizing current remains stable in the machine. Heat generated by semiconductor switching is removed through a plug-through cooler for drives up to 110 kW, which places the heat sink outside the cabinet and transfers losses directly to ambient air, reducing temperature rise inside the enclosure.

The unit is supplied without a built-in brake chopper, so an external resistor is needed when rapid regenerative deceleration is required. Line-side harmonics are reduced by an integrated mains filter, which simplifies EMC compliance and avoids separate filter wiring. Component tolerances on key analog measurements are held to ±10 %, supporting consistent response of reference and monitoring circuits under normal operating conditions. The platform is generation 1, and the controller is supplied without auxiliary option cards.