Product Description:

The RD51.1-5N-090-L-LV-FW is a drive controller built by Bosch Rexroth Indramat for the RD 500 Drive Controllers series. It is intended to regulate asynchronous motors in automated machines where open-loop speed management is acceptable and a dedicated fieldbus interface is not required. In an installation, this unit converts incoming three-phase power, modulates the output frequency, and adjusts motor speed to match process demands while protecting the connected load from inrush and stall conditions. This operating method suits applications that need adjustable motor speed rather than closed-loop positioning.

The input side is arranged as a three-phase AC converter, so the device accepts balanced mains without an additional rectifier stage. Once energized, it applies U/f curve control, a method that keeps the stator voltage-to-frequency ratio constant so that induction motor flux remains stable across the speed range. It can drive continuous mechanical loads up to 90 kW, and heat is removed by forced air cooling to maintain thermal limits during sustained operation. Dynamic braking energy must be handled by an external resistor because the unit is supplied without a built-in brake chopper. The hardware corresponds to design generation 1, which matches cabinet dimensions, I/O locations, and diagnostic procedures common to other first-generation RD 500 controllers.

The power section is optimized for the 500 V class, while the control electronics can remain active through an auxiliary 24 V standby power feed wired from an external source. This auxiliary supply allows control functions to remain available when the main power stage is not active. When long motor cables are unavoidable, the integrated algorithm for cable damping feedback (C3, D3) compensates for capacitive voltage drop to help keep motor flux constant. Application-specific behavior depends on the ordered software package, which is supplied as a separate software subposition.