Product Description:

The RD51.1-5B-022-D-DF-FW is a control unit manufactured by Bosch Rexroth Indramat within the RD 500 Drive Controllers series. Designed for cabinet mounting, the module regulates three-phase induction motors in material-handling lines, pumps, and general plant automation by adjusting speed and torque to real-time demand. It forms the interface between the mains supply and the motor, converting fixed-frequency power into a variable output that matches process requirements. This arrangement allows the controller to combine power conversion and motor regulation in one cabinet-mounted unit.

At its core, the unit employs U/f curve control, a method that keeps the voltage-to-frequency ratio constant so the motor develops stable flux across the speed range. The inverter is rated at 22 kW, giving it suitable capacity for medium-sized conveyor or blower motors. It is supplied through a 3 × AC converter front end that accepts three-phase mains in the 500 V range and rectifies it before modulation. A built-in brake chopper dissipates regenerated energy during fast deceleration, so an external braking module is not required. Heat generated by the power stage is routed to a plug-through cooler, which is applicable up to 110 kW and supports dense cabinet layouts without exceeding ambient limits.

This controller belongs to design generation 1, so it follows the first RD 500 platform layout and requires matching option cards. For system wiring, the front panel carries a NAMUR terminal strip that also provides 24 V standby power from an external source, keeping diagnostic circuits active when the main bus is off. Drive status can be supervised through current filter feedback (U6, V6, W6), allowing a higher-level PLC to observe harmonic damping in real time and adjust process parameters accordingly.