Product Description:

The RD51.1-4B-055-L-D1-FW is an AC variable-speed unit produced by Bosch Rexroth Indramat and belongs to the RD 500 Drive Controllers series. By converting three-phase mains power into a regulated output, the device governs the torque and speed of induction motors used in conveyors, mixers, and process pumps. In automated equipment, it sits between the plant low-voltage supply and the motor terminals, providing controlled ramping, braking, and protective functions so machinery can maintain repeatable operation during normal starts, speed changes, and stopping sequences across routine production cycles.

Its continuous output is rated at 55 kW, allowing the controller to run medium-sized motors without derating. The input side accepts 380 to 480 V three-phase service and remains within regulation across a ±10 % mains fluctuation. Because the hardware is a 3 x AC converter, rectification and DC-link buffering are built in, so no external transformer is required. Heat is removed by forced air cooling, which moves cabinet air through the heat sink. During deceleration, a built-in brake chopper shunts surplus DC energy to a resistor and helps prevent overvoltage trips on the DC link.

Motor magnetizing flux is established through U/f curve control, which matches output frequency to proportional voltage for stable torque delivery across the speed range. Line-borne interference is attenuated by an integrated mains filter, helping the drive meet common EMC limits without additional line reactors. Classified as Design Generation 1, the hardware shares mechanical dimensions and option slots with other first-generation RD modules. The front panel includes a NAMUR terminal strip for process signals, and an external 24 V standby supply keeps the control panel active when the main power is isolated.