Product Description:

The RD51.1-4N-090-L-D1-FW is a drive controller manufactured by Bosch Rexroth Indramat and delivered within the RD 500 Drive Controllers series. The unit serves as the power-conversion and motor-management layer in automated machinery, converting three-phase mains energy into regulated output for induction motors. Installed in cabinet-mounted control stacks, it allows speed and torque adjustment through scalar voltage-to-frequency profiles. This operating method suits pumping, conveying, and material-forming duties where asynchronous motors are commonly used. It supports variable-speed operation in equipment that needs steady motor control rather than highly dynamic servo performance.

This model supplies a continuous mechanical output of 90 kW, which suits mid-size production lines and larger process drives. It accepts an incoming line voltage of 380 to 480 V and uses a 3 × AC converter supply, so no external rectifier is required. Control is handled through U/f curve control, meaning voltage rises in proportion to commanded frequency to keep air-gap flux stable in standard induction motors. This control method is common where stable speed regulation and straightforward motor operation are more important than rapid dynamic response. Thermal energy is removed by forced air cooling, with ducted fans moving cabinet air across the heat sink to keep power semiconductors within normal operating temperature limits.

The unit operates without a built-in brake chopper, so braking energy must be handled by an external resistor module when rapid deceleration is required. Harmonic mitigation is assisted by an integrated mains filter, and output precision stays within a ±10 % tolerance band across the stated voltage range. Field wiring uses a NAMUR terminal strip with external 24 V standby power, which provides galvanically isolated signaling during line outages and keeps the control interface available when the main supply is absent. The design belongs to generation 1.