Product Description:

The RD51.1-4N-018-L-D1-FW drive controller is manufactured by Bosch Rexroth Indramat as part of the RD 500 Drive Controllers series. It is an inverter stage intended for industrial automation where variable-speed operation of standard induction motors is required. By adjusting output frequency and voltage, the unit allows conveyors, mixers, pumps, and similar machinery to match motor speed to changing process demand. This operating method supports smoother acceleration, steadier process control, and reduced mechanical stress during normal production cycles.

The unit accepts three-phase mains through a three-phase AC converter input and operates across a line window of 380 to 480 V with a permissible deviation of ±10 %. Within this range, the controller delivers a continuous output rating of 18.5 kW, which suits many mid-frame industrial motor applications. Speed adjustment uses U/f curve control, so output voltage is reduced in proportion to frequency in order to maintain usable magnetic flux at lower speeds. This control approach is commonly used where reliable speed variation is needed without the complexity of closed-loop vector regulation.

The enclosure uses forced air cooling, so fan-driven airflow must remain available to remove switching losses from the heat sink during operation. Because the device is supplied without a built-in brake chopper, rapid deceleration of high-inertia loads requires an external braking arrangement. An integrated mains filter helps reduce conducted interference on the plant supply, while the control connections include a NAMUR terminal strip for process-oriented sensor wiring. A separate 24 V stand-by supply can be connected to keep internal logic active when main power is isolated, which helps preserve control availability for monitoring and restart functions.