Product Description:

The RD51.1-4N-018-L-DF-FW is a drive controller manufactured by Bosch Rexroth Indramat within the RD 500 Drive Controllers series. In an automation cell, it links the incoming three-phase mains to an induction motor and regulates speed and torque so conveyors, mixers, or pumps follow programmed commands. By modulating the output frequency and voltage, the unit supplies the motor with the electrical profile requested by the programmable logic controller. This makes it suitable for variable-speed industrial processes that need stable motor control across changing load conditions.

This controller delivers a rated power of 18.5 kW, which is suitable for medium-sized production machinery. It accepts line supplies in the 380 to 480 V range and is built as a 3 x AC converter, meaning it rectifies a three-phase input before generating a variable AC output. Speed regulation is based on U/f curve control, so the output voltage follows a preset relationship to frequency and helps maintain proper magnetizing current at low speed. Internal heat is removed through forced-air cooling, which supports continuous duty at full load when cabinet airflow is maintained. The power stage and control boards are built to design generation 1, and the line fluctuation tolerance remains within the stated operating window.

An integrated mains filter suppresses conducted emissions, while the unit is supplied without a built-in brake chopper, so dynamic braking requires an external resistor when rapid stops are needed. The permissible input swing remains within ±10%, and the front panel includes a NAMUR terminal strip with external 24 V stand-by power so connected field devices can remain energized during a mains interruption. Current feedback from the U6, V6, and W6 links helps the control board monitor filter loading without requiring additional transducers. This arrangement supports stable supervision of the power section during normal operation.