Product Description:

The RS51.1-4G-031-U-NN-FW is a basic AC drive controller produced by Bosch Rexroth Indramat within the RD 500 Drive Controllers series. As a basic drive, it converts three-phase mains power into a regulated motor supply for pumps, fans, and conveyor sections in factory automation. The unit adjusts motor speed through voltage and frequency modulation so that mechanical output follows process requirements while meeting plant power requirements. This operating style suits applications that need dependable variable-speed control without the added complexity of high-performance motion features.

This controller uses U/f curve control, a method that keeps the motor's magnetic flux nearly constant by changing voltage in proportion to frequency. This method is commonly used with standard induction motors in process equipment. The incoming mains can range from 380 to 480 V, giving the device compatibility with common industrial low-voltage networks. Line variations up to ±10% are tolerated without shutdown, which helps the drive remain stable during brief utility swings. The inverter section is rated for 31 kVA, allowing it to supply medium-frame induction motors under continuous load. Power is accepted from a three-phase AC supply, so the input is rectified and modulated internally rather than relying on an external DC bus.

An integrated mains filter attenuates conducted emissions, so additional line filtering is often unnecessary. During rapid deceleration, the drive uses a built-in brake chopper and resistor to dissipate returned energy and prevent DC-bus overvoltage without external braking hardware. The platform is classified as a basic drive, so it focuses on core speed-control functions for standard industrial motor applications. The mechanical layout follows Design Generation 1, which keeps the housing arrangement aligned with the first RD 500 cabinet drawings. This layout keeps terminal access and cooling space in the expected locations inside the cabinet.