Product Description:

The RD51.1-5N-075-L-LV-FW is a variable-speed drive unit produced by Bosch Rexroth Indramat within the RD 500 Drive Controllers series. It interfaces with three-phase induction motors and adjusts their speed to match process demands in automated lines, conveyors, and pumping stations. By modulating output frequency in proportion to the selected U/f characteristic, the device supplies the torque profile needed for constant-torque and variable-torque loads while keeping cabinet space requirements moderate. This allows smooth speed adaptation for process equipment that must follow changing load conditions instead of operating at a fixed line frequency.

Electrical hardware on this model omits dynamic braking circuitry; it is supplied without a built-in brake chopper, so regenerative energy must be handled externally or returned to the mains. The input side accepts a three-phase AC supply and is optimized for a nominal line voltage of 500 V, matching common industrial distribution systems. Internally rated for 75 kW, the power stage can deliver full output when its heat sink is kept within limits by forced air cooling from the integrated fans. In applications with frequent deceleration, the lack of an internal braking stage means the surrounding system must manage returned energy so the DC bus remains within its normal operating range.

Control logic uses U/f curve control, which maintains a fixed voltage-to-frequency ratio so motor flux stays stable across the adjustable speed range. This control method is commonly used where straightforward speed regulation is preferred for standard induction motor duty. The hardware is classified as generation 1, which places it in the first design generation of this platform. An auxiliary supply provides 24 V standby power, allowing the control electronics to remain active when the main bus is de-energized. Application-specific adjustments can include cable damping feedback, which helps the drive remain stable in installations with long motor leads.