Product Description:

The RD51.1-4B-018-L-CF-FW is a drive controller produced by Bosch Rexroth Indramat and included in the RD 500 Drive Controllers series. It is intended to operate standard three-phase motors in automated machinery by converting fixed mains power into a variable output that matches the process speed requirement. Through its voltage-to-frequency regulation scheme, the device supports energy-efficient control of pumps, fans, and material-handling equipment on plant floors. This makes it suitable for applications where process speed must change during normal operation instead of remaining at a fixed motor speed.

This controller delivers a rated output of 18.5 kW, so it can drive loads within that power range without derating. It accepts line voltages from 380 to 480 V and allows a permitted line fluctuation of ±10 %, which helps it remain stable when incoming power varies. The motor flux is regulated by U/f curve control, a scalar method that keeps the voltage-to-frequency ratio consistent across the speed range. A factory-installed integrated mains filter helps reduce conducted emissions on the supply line. This control approach is commonly used where simple and reliable speed adjustment is needed for standard industrial motors.

The drive includes a built-in brake chopper, which diverts excess DC-bus energy to an external resistor during rapid deceleration. This is useful in applications where a slowing load returns energy faster than the drive can absorb it internally. Thermal management uses forced air cooling, so cabinet airflow must be maintained during continuous operation. Power enters through a 3 x AC converter front end that rectifies the incoming phases before feeding the inverter section. The unit is part of design generation 1, and its C1 + F1 function set is enabled in the type code for the associated control and diagnostic functions.