Product Description:

The RS51.1-4G-031-S-NN-FW is a drive controller manufactured by Bosch Rexroth Indramat for the RD 500 Drive Controllers series. This unit is used in industrial automation to regulate the speed and torque of three-phase induction motors, acting as the central power converter between the plant mains and the motor load. By maintaining the proper electrical relationship between the grid supply and motor terminals, it lets machinery operate at commanded speeds while protecting connected equipment. This supports smooth operation in conveyors, pumps, and other production equipment that requires controlled acceleration and stable running speed.

The controller is rated for 31 kVA of apparent power, giving it enough headroom to feed medium-sized production motors under continuous duty. It accepts line voltages in the 380 to 480 V range, so typical European and North American factory mains fall within its operating window without step-up or step-down transformers. The unit uses a 3 × AC converter supply topology that rectifies incoming three-phase power and creates the DC link for inverter operation. Motor excitation follows U/f curve control, so the controller maintains a stable voltage-to-frequency relationship as speed changes. During rapid deceleration, the built-in brake chopper and resistor dissipate excess DC-bus energy internally, which avoids the need for a separate external braking module.

An integrated mains filter attenuates conducted emissions, helping the installation meet electromagnetic compatibility limits without extra hardware. The unit belongs to Design Generation 1, which places it in the first RD 500 release group and keeps its diagnostics consistent with related models. Input fluctuations are handled within ±10 %, allowing the drive to remain online through normal plant voltage variation. As a Basic Drive, it omits application-specific functions and is intended for standard variable-speed control where the core converter functions are the main requirement.